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Phosphonium salts and phosphoranes—VI1
PHOSPHONIUM SALTS AND PHOSPHORqNES-VI1 “P NMR SPECTRA OF ACYLMETHYLENEPHOSPHORANES Ju~nr M. BRITLUN and R ALW JONES+ Schoolof CbcmicslSchces, Universityof East An&a, Norwich NR4 7IJ, Englmd. (Recekd In UK 2 oclobu 1978)
In the cuurse of our study of the thermal decomposition of tbc beWoaroyimethyknephosphoranes,l 1 and 3, it was of interest to disuwer whether there was any dilfereaceintbeekctronkstructuresaadintbepreferred conformations of the isomeric pbospburanea,which would a&t the e5cklKy of their conversion into the heteroarywyw, 2. Ar’.CO.$.Ar’
A$.CrC.A,‘-Ar’.C.CO.Ar’
_
5. d II
ijPh,
Pph,
I
3
2
H- -
R’
R’
0
R'
+PPh,
PPh,
40
4b R’
v-c
0
R’
+P Ph,
R’
O-
-
negligiik interaction between the quaterwy P’ atom and the anoinic O- atom of the chid htterionic sbucture (4) and although at low temperature, structures anakgoustotbeCmemberedring6havebeencon6m~d as intermedhs in the w* synt&sis of alkenes: such stIllctures have little importance in the ground state strum of the acyhethylenephosphoranc3. The equiliium position for the two cunformers, 4 and
H
+PPh,
tk
I’OtdOld
CllClW
barrier
bCtWWl
tk8C
UMl-
f&men should be affect&j oat only by the electronic characterofR’butshouldalsodependupontbedegree of interaction of Rz with the CO group. In particular,an ekctron-withdrawing R2 substhat would be expected to deshbilixe the zwitwionic structures 4b and sb. Similarly, sterk in&action between the aryl substituents .and the triphenylphosphoryl group should Educe the c&wity of the phosphrane system with a consequent destabilixath of the canonical forms 4b and sb. “P Chemical shift data have been accumulated for a widerangeofphmphwsuunpounds9anditisapparent that “P NMR spectroscopy could provide a ~osticpfobeforthes~oftbeinteractionoftheP atom of tbc phosphoranes with the acylmethylene group. However, no systematic survey of the “P NMR spectra of acylmethykae phospboranes has been reported.
Sb R’
R’ w
0 -
PPh,
6
In previous confstudied of acyhethyknepbospboraws 4*5 extensive use has been made of variabktempenwe’HNMRspectrwop~‘aaditis evident that, when R’ # H, the cisoid structure 4 predominates,attln@itkasbu?nlKMdtbattJEbulkof tbeR’substhnta&tstheequiliiposition.’Botb conformers of the formylmethyknephphaae (4 and S;R’-d-H)exhtinequitibriuminaca t:lratioat room tempeMw,&’ but tbe presence of a strongly electron w&drawing sub&u&, R’, produces an increaseintt.terektivec.oecentrationofthefmn8o&fconformer.“Tlle’HNMRdataalsoMicatedthatthreis
The “P NMR cbmical shifts of the simple acylmethykae pbospboranes (PW=CHCOR), presented in Tabk 1, were in accord with previously reported ‘HNMR data for analogous acylmetllylenepbosptmranes~’ and Micated that, with the exception of the formyl compou& only ‘one conformation exists in &uterdloroform and in deuterobenxene. Comparison of the ma&&s of the observed ‘IP CWdShiftsWithpnviouslyrep0rtedvalues for acyiphosplmranes of known conformation7*‘zcon6rms that the wmpowds under inveshgation have the cisoid sbWure4.TbeshkldingeffectontbePatomoftbe YMe% signal
as observai in the UpfMd shift of tbc rmoMllce Compared With the &&cal shifts of the c.or-
responding pbosphonium salts, is compatiile with either the da-pa inhaction between the P atom and the carbanioniC0l0thykmgroupofIr ortbeconjugationof the phosphonium group with tbc enolate anion w-system
J.M.Barr~~~~aulRA.Jowra
1140
Table 1.“P NMRckadcal Mb for acyh&bylenepborpbaraa (Pb,lWHCOR)md the m pborpboaium W&W (l’l&!EgOR) phosphon%lY5 Selt
PtXMphoreUe
R
in C6D6
in CDCl3
Hydrogen
in CDC13
-15.0 -19.1 5
Methyl
-14.8 a
-15.8
-13.6 -20.1 2
1-mthyl-Z-pynolyl
-16.6
-17.2
-22.9
P-Thienyl
-16.9
-17.5
-22.1
2-Fury1
-17.2
-17.8
-22.3
PheIIyl
-17.2 d
-17.9
-22.3 2
5
cleoid fom7 -15.0 p.p.m.; trmuoid form7 -19.1 p.p.o.
c
high field el.gnel due to em1 form.12
a
lit,,13
a
2
lb.,12 -14.7 p.p.m.
lit.,13'14-16.7 p.p.m.
-20.7 p.p.m.
Of~~~~Of~~~~f~~ p&spaorancaill~~f~n?~t4dK: cbmicd shift8 of the corresponding CompWds
measuredindeuterobenxene,arccoMi8tenttia greater cuntriition of the exteadcd conjugated system (4b) to resonance hybrid in the more polar soIve& Such ~eff~~d~e~by~~~~~terochloroform to SpeciiIcally8olvate the ylide through H- bondingwith t& enokte 0 atom. This inteqretation of t& solvent shift Mers from that proposed for the solvent e&t upon the ‘H chemical shifts of the conforImtionauy mobik ethoxycarbonylmethyknephOBpilOraneS’” and for the formyhnethyknepbsphwa~cs;'in which it was sqgestcd that the more polar solvent &Slid the fmdif cxmf0rmah. Them is m evidence from the “PNMR spectra for the presenceof the four-memlzred cyclic structure (6)” in either solvent. ‘l%evariationinthedeshkld@eWtofthearyl Wbstituentupon the phosphorous mlckus of the amyl~~yk~~~~ is small and follows the order:
eon-
of ‘%NMR data for alkoxycarboaylmethykIleylides,“batmaybemtioMl.izedintermsof
freqlleEk8 observed for the a4Wy! CQmpoimda”are also in ageementwithtbe~enokteaaion StrucWe. It~~~~~~~~~ of alkoxycarbonylmethyknepho8payteaepaMyrboraaes is sensitive to thestericbulkofalkylRroops,R’,ontheaubanWc centre.‘&boll&hary1aubstitWnt8tendtosEabitiu:the cisoid rotamer.lo30coMilltent with these obllervations, each a-aryi-a-aroyhnethykne-pho#omne exhii only ooe “P msonance sigual, which, by qalogy with the simpk aroylmethykne =mpounds, we have aftsigned to the &o&f &Mner(Table2). However, the introdWtion of the (betero)aryl sub8tihKntat the a-position of the produceda&a-heteroaroylmethykn tinct de&&@ e&t upon the dbosphorus nucks when the spectra were measured in Cm3. The greatest e&t was observed upon the aeon of the 2--l 7 (l.tW.9ppm), whi!st the phosphorus nucleus of phenyl> 2-furyl> 2-thkllyl> l-methyl-2-pyrrolyl. e 2-thtenyl and l-methyl-2-pyrrolyl derivatives was deahklded to a smaller extent (0.7This order approximatesto the expected inductiveekc- 0.9ppm). The smalkat e&t was observed for the atron_witbclrawiaepropertiesoftbearyl~andistbc p&nyl compou& (0.2o~ppm). In contrast to these invcnic of theirfrle-mdcekctropdoaatipgabili?y.TEis obsmations, the int&lChoS Of 8 @Cell, 2-thimlylOf ~~$~~~~~~~I~~~ l-~~~2~~lyl groupat the a-positionof the benzoylP-CL’0 plane, as Scsted by X-ray measureme& in rn~~e~~~p~~~~~w~ the solid state for an8k#oua compom&U pcr5%a in the 2-fury1derivative resonated at lower &Id. Sohlt&.BothtbeiMhKtiWettcctandtheClDSS-i%l!Mokudarmodelsahowthf&forthecMdro~r, jugatio~oftheCOoroupwiththeary1ring~the lleitkbetCfOCyCiiCliOgCanlkilltb8S8Olephlle~tbC c&amonic ceotre have a de&&G& effect up00 the bC-6 ay8tcm ad the deslkiddhg effeds Can be ~~~~~~~ch~~~~~ . . ~*~Cff~~~~ ~~~ofa~~~~d~-p~~~ ~~of~p~~~~~~~ ~~k~~rex~~~~~~~*H~ +system,asareaultofthei$ictiveekctron-with-. shiftsofthemethyk.neprotonwiththechaoSoftbe aroyl &atitumt. However, the small ransc of the drawal by the a-beterorrryl s&Utuent~~.“~ The “achemical shift8 (a 4.05-4.38ppm) Micated that the wbatituent effect” was ksa regular, when the spectra overrid& conjugative inter&on for the simpk acyl- were measured in S but.ingene&a methyknepho@mmes is bed represented by Ib. This &shkunge&twasobnervedforallP-arylder+vaconclusion differs from that previoosly reached from a tives, with the exe&on of the a-(2*furyl)compoo& It
1141
Tabk 2 “P chmid
A2
difts for (a+royl-a~P’iph~
-
in
-1
phenyl n
I,
n
II 2-Thienyl 11
in
C6D6
-16.0
-15.0
1-t4thy1-2-pyrro1y1 -16.8
-16.2
P-Thiemyl
-17.1
-16.5
2-Fury1
-17.5
-16.8
1-Mehyl-2-pyrrolyl phanyl n 1-Methy1-2-Py7m1y1 II
CDC13
-16.7
_
-17.4
-16.9
2-Thhlyl
-17.7
-17.8
2-Fury1
-18.1
phenyl
-16.9
1-Methyl-2-pyrrolyl -17.3
-16.25
n
P-Thienyl
-17.7
-1723
1,
2-Yuryl
-18.7
phenyl
-17.6
-17.2
I,
1-Methy1-2-pymo1y1
-18.4
-17.8
1,
2-Thienyl
-10.0
-18.7
"
2-Fury1
-19.1
-18.8
2-Fury1
Tabk 3."P c.&cmidabifts ofa-selyllada-benzoyhwth~
(Ph,P4!Rz~~R’)
LJ31Pillctx.il 3
AC
m
H
-14.8
0
ne
acety1
-16.6
-2.0
24
1-mcthy1-2-pyrroloyl
-17.0
-2.2
M!
2-thewy1
-17.9
-3.1
Me
P-furoyl
-17.0
-3.0
m
b==Vl
-18.8
-4.0
ph
H
-17.2
0
Ph
acetyl
-18.8
-1.6
Ptl
1-m8thy1-2-pJmro10y1
-17.7
-0.5
Ph
2-themoy1
-19.0
-1.8
Ph
P-fllroyl
-19.1
-1.9
Ph
WY1
-19.0
-1.8
5
A
-
8 (R2-acyl)-8
(R*-i#)
1142
J.MBilnTAlNaDdRA.JoNss
thermal fragmentation of the a-henxoyl-a-beteroaroylmethyknepbospboranes to give the l-ixeteroaroyl-2pheqykthynes (Ar-CO-CxCPh).’The larger and more variable “a-acyl effect” rest&& from the inboduction about the C-C bond of the b%=O system wouldallow of heteroaroyl groups at the a-position of the acetyla greater degree of mesomeric interaction with tbe methyknephospboratk indicated a greater degree of heteroaryl ring!& conjugation of the heteroaroyl group with the carThe introductionof a second a-acyl substituentto give banioniccentre and that both (7b, R=Me)and (7~.R-Me) the a,adiacylmethyknephosphoranes had a signi6caat are impmtant canonical sbuctmes. This resonance deshidding effect upon tbe pbusphorus nucleus (Table stabilixatb is retkcted in the almostequivalentyields of 3). The “a-acyl effect” had a greater intluenceupon the tbe l&eMoarylbut-I-yn-3-ones(Ar-C&-CO-Me)and l“P chemical shift of the a-acetylmethykne- he&oarylbut-3-yn-lunar (ArCOGX!-Me), obtabad phosphoranes (2.0-4.Oppm), compared with the a- upon thermal fragmentation of the u-acetylsbenxeylmethyknephosphoranes (0.5-1.9ppm). By heteroaroylmethyknepbospberanes.’ analogy with tbe preferred conformation of tbe ‘free” similarly, the downtkkl shift of tbe “P resonance anion of @diketones,~ the a,adiacylmethykne- signals, observed upon the formation of the a-acyl phosphoranes would he expected to adopt the con- derivatives of ethoxcarbonylmethyk@rorane, can he formation (7). An inspection of mokcular models, attriitedtoapreaterdekcati&onofthecarbanionic however, indicated that only one acyl group could con- charge. Hence, ahbough steric hi&ance prevents jugate effectively with tlk carbonioniccentre. copkbtyofhoththeRgroupandtbeestersubst&nt is probable that. with the des&Gng effect of the deuterobenxene upon canonical structure 4b. the ylide structure 4a tEc4unesmore importantand partialrotation
P A
Ph,L
\
with the bC-6 system, aumnkal stnmture @e) wouldbeexpectedtoprovi&amajorcontrkutkntotJk resonant hybrid. By analogy with chemical shifts observed with the simpk aroylmethykne compounds (Table 1). it is apparent that the aryl groups Raveessentially only an inductbe ekctron-withdrawingintluence on the system and the variationof tbe “P chemicalshift withtbechangeinthearylgroupisnegligiieflabk4).
8
-R
+
-
/c--R
PhsP-C+C_Ar
fi-Ar
b-
0
70
7b
+ Ph ,P-C
?//C--R \
5-A’
Ph,P+-C
0 7c The
ahost constant and small “4-acyl effect” obser-
/ \
Ph,?-
$-OE’
\\
$-OE’ 0-
aa
ab
8’ Ph a-6
Cd’-’ \
E-OE’ 0
ec
for actboxycarbonylmeU~yIeWr+heoykb&i~~(Ph,l’=CRC4Et)
&ifts
631P in clxx3
AS
A-
0
+3.3
b
n
-17.g
acetyl
-18.1
-1.1
-3.3
benzoyl
-19.4
-2.4
-2.2
2-furoyl
-19.4
-2.4
-2.2
2-thwyl
-19.4
-2.4
-2.5
1-methyl-2-pyrroloyl
-19.4
-2.4
-2.8
a
A
a
A -
r
C-R
/ C
0
ved for the benxoylmethyknep~s and the relatively constant value for the “P chemical shifts of these derivativesis compatiik with(7~.R = Ph) beii the more important canonical structure. Tbe “a-acyl deshklding e&t” for t&se. compounds consequently arises from the inductive electron-withdrawingeffect of the twisted non-conjugating heteroaroyl group. This postulate is in accord with the observed preferential Tabk 4. ,‘P cbmical
0
i? C-R
-
6 @-a~yl)-6
(R-H)
b (Ph3P-CR.co2Et)-6 (P+~~PICHR)
lit.,24 -16.8 p.p.m.
Pbosphonium s&s and pbosp&ranes-vI’
1143
(a - 2 - Fwyt - a - 2 - t~~mcthyl~)~~y~~sphomnr (!M%),m.p. l%-lP, dcc. (Fold: c, 74.0; H, 4.8. C2sH*rozPS
-AL
“PNbfRspxtrawc~-crux~daiusingrVariimXL-100spcc-
(!i#%), IX&.K&i%’ @oun& C, fi0.s; H, s& N, 3.2. C.,H,sNOP reauina: C. 81.0: H, 5.7: N. 3.1%J. (a - Bau@ - i - 2 - jWyJGd#&~~~~~SphO~ (99%). qp. 19219y (pouad: C. 8O.R H, 4.9. t&H&P nquirea: C. 89.7; H, 5.2%). (a - Be~~zoyl- a - 2 - th&nytmethyk)t&riplSarrblkorplronuu (!H%),m.p. 2tNP(Found: C, 77.7; H, 5.2. CJ&OPS nqti: C, 77.s; H, 5.0%). (a - 2 - ?Moyi - 0 - 2 - t~y~~~)~~~pwp&omw @f%)* m.p. 188-1W Wlmdz C, 71.4 w, 4.6. C,&OPS rcqmrcs: C, 71.8; H. 4.5%). (4 - (1 - Me&f - 2 - pydyf) - a - 2 - Ml&mcthyt~eWphaWho~pho~e (71%), m.p. 216218” (Found C, 74.9: H. 5.6: N. 27. CmHdJOPS rcdcs: C, 74.7: H, 52; N, peppy-
pho@trmhm~ chloride. W.8~
80%) m.p. 22%W
Wundi
C,
68.1: H, 4.9. C&&lOPS re@irea: c, 68.2; 4.8%). (l-Mtt&~-2-pynv&yf)h&J~jdpho#phaJIimm chlo?fdsz lbalk (9.7& 0.12moQ and 2,b&id& (12&g, 0:12mol) in CHCh WOmlI were added over a wrkwf of ca 1Jltr to a Je~iqt-sobJ of &loNWyl cbkridc 03.6 & 0.12mol) in CHClJ (aoJlli& The JDixtmt wM rduxed for 2 In ad tbc solveot ~v~~n~~r~~~~~vea~wti~ wucoaeclrdrPdwadwxlwitbctbcr(soall).TbscoalbiictJlcr extmcts were wasbed successively witb 3NHCl(2x3Oml) and
H, j3f N, 53, C&&0$ &ire& C, R.5; H, 54; N, 3.1%). (~-(1-~~~-2-p~~-a-2-t~~h~~)t~~~&o&oruiw 181461, m.n Wdec. (Pou& C. 74.k H. S1: N. 2.8% &I&, NOPS mquircs: C, 74.7; H; 5.2; N, 3.0%); ht - (1 - kthti - 2 - DYJW&fi - (I - (1 - m&Y/ - 2 -
wrta (5 x loom& dried (a&So& and cvaporatd to give a ye&w oil. wbkb on tdumtion witb pctrokum& (40-W) s&d&xl to give 2doraaMyipysYok (12gI 65%)*m.p. [email protected] m.p. 474. Tbc 2~~~~ (~~-0.~~) was converted into (l-mUhyi-2-py~~~~y~~~~ chlor& (11p. si%), m.p. 238-2391(F~~LI&C, 712 H. 5-S: N, 3.4. C&,ClNOP requires: C, 715: Ii, 5.5: N, 33%) by a procubue adogoua to tbat de&xii above for thesynthcs~of the tbiopben Jdogtlc. BqJadM of Phosp&wuJW3*The known acyllldykJmpboqoWwcre~ffomtbceornspo~~~ pbomtJmdtsbyo=tbodsdcscAdintbcWaturc. ~rn.~w~~~nt~~~~~~ andfRaad’HNMRspccaaldatawerccomp&kwitbti~~ cxpixted vahbs. TbcbitbatowreportedwmpoundawenpJepadbytbc f~~~~~~ (a-~~~-a~~~~~~~~ea The appm&ak arylmeiJlyltii&n~llium chloride (0.03mo9 was a&id witb stirr& to freshly prqmred NaOEt (0.03mol) in bmtzcne (IWml) under Nt.” Tbe mixture was stinsdfor4SmiaItU*arwltbeE(oHwarnmovedbyrrzeotropit dktiuon. The aaofoDJiatc arovl CbloJide Io.o1slDon in
- a - (I- methyi - 2 - pym~lyl)muh@Jc)t~$~he~~ylC, 80.$ H, ti& N, 2.9. C&&OP requires: C, 81.0; H, S-7; N, 3.f%). (a - 2 - M - a - 2 - thawytmethylaw)trfpktnytpkosphonmc (5’4%) m-p. 189’. dec. (PopDd: C, 76.6; H, 4.9. C&i&P nsuirca: c, nR; H, 4.9%). (0 - 2 - Bmyf - a - 2 - !Matykth~)t~htnyfphoap~~ (9246)m.p. 177~1W (Founds C, 74.2: H, 4.5. C2JI&FS phoapkomne ilOO%),rm.p. 1225-1230(PO&: C, 70.& ir, j.0. Jequins: c. 74.3; H, 4.7%). C&H&d’s nauires: C. 70.7: H. S.l%b (a - 2 - &U$ - a - (1 - mdyf - 2 - $y~y~m~~~t~~~~~ (73561, m-p. 232-233”(pourd: c. 77.2: H, 5.3; N, 3.5. &&N&P reqircs: C, 77.3; H, S.4: N, 3.1%).
1144
J.M.B~~~~AIN~IMIR.A.J~
(a - BenwyI - a - (1- InerhH - 2 - pymdo~)mJthyiaw)triphalyl(1 - Methyl - 2 - pylroky0mctbyka?fIipbenylpboxpbafw (1.14& 0.003mol) xDd balxok Mbydl+k (1.11. 0.005ID00iu CHCI, (15 ml) were realxed for 12hr. Tbc sdvcot w8arcmovcdaadtbcfeaidudoilaNctedwitbpctrokumetber (b.p. 6M#r, 5 x I5 ml) to nmove tbc cxcca8 knxuic mlbydrik. Tihntion of the residue with dktbyl ether: bexane (1: I) gave (abaud - a - (1 - rndhll - 2 - PwWWWWWWphosphotw (136g, !I3%), q.p. 211-214n(FoundzC.ltO.l. H. 5.4 N, 27. &&N&P rcquirw C, 79.8. H. 5.3; N. 29%). Pllospikomnr
A&no~a~&--We tbxnk Dr. R. K. Hti tbe”Pp.oberodMr.P.HxylettforY~in~tbe”P rcsonxnce w J.M.B. g&fully akwwk&s xll S.R.C. lBFiiatelmIlCc ggarlt
for tbc loan of tbc receipt of
‘PutV.J.M.BritbinPadRA.Jwes.I.CikanRtkaubmittcd for pubuion. Q. J. Bcstnmnn and 1. P. Snyder, 1. Am. Chun. Sot. 89.39% (1967). ‘H. L Zdi~a, J. P. Snyder and H. J. Bestnmnn. Tern&&~ JiurerJ 3313(1970). ‘J. P. Say&r xnd H. 1. Beatmum, Ibid 3317(1970). ‘I. I? Who xnd J. C. T&by, &id. 3769(1970). ‘IA. L. FiBeux-Bkndmrd aad M. G. J. AMio. C.R Acad Sci, Pad8 27#c, 1747(1970). ‘Cc.J. Devtiu ami B. J. Walker, Tdmkdmn L4#clv4323(1971); Teh&edm 1.3501(1972). ‘S. Trippat, Pm AppLCkm. 9.‘255(1954). ‘see, eg, G. Mxrvd. Annual Repott~ of NMR Spectrurapy (Edited by E. F. Mooney), Vol. 5B. Academic Resr. Ladon (wn). xnd s&c&lilt P&did Rqolt3 on orpMoprkosprkons Chcmlstty,vol.3 14 The chemical !3ockty, London (1970-n). “J. P. Snyder, Tdmhedtm L&ma 215 (1971). “cf. CLH. Binun xnd C. N. Matthews, Chew Comma137(1967); E. Vukjr xnd K. A. J. S&k. I. Aa Cha &c. 95.5778 (1973): E. Vedejs. K. A. 1. Snobk and P. L. F@m, 1. Otx. c&em. 3& 1178(1973). ‘15. A. Nermeyaaov, S. T. Bermxn, P. V. Petrovxkii and V. I. Robaa, M Acad Nauk SSSR 22#, 1372(1975):Chea Abrtr. a 138no (1975). “F. Ram&, 0. P. Madau sod C. P. Smith, Tetmhedm 22,567 (1966). ‘+Ibchieberv~uerecordcdbyA.J.SperkkladK.W.Raas.I.
Am.chalLsor.I,279o(1963)i8tbxtofsampkcoa~ by the pboapbonium sdt. “I’. S. Stepben. 1. Chat. Sot. 5658(1%5); A. J. Spexixk awl K. w.Rlt&J.AJn.aa&c.87,5603(1965). ‘6. A. Gray, Ibid %,7736 (1973). “J. M. Brittxin, Ph.D. Tkais. Uaivaity of Exat Anglk (1977). “See P. J. Taylor, &ecbuchia AC& 34,115 (1978). ‘q. Zcligcz, J. P. Snyder and H. J. Butmano, Tetmhdmn I.‘drm 21% (1969). =D. M. Crauae, A. T. Webman xnd E. E. Schweixcq Chem. &mm. 866 (1968). “See S. 0. Grim, W. McParkw and T. J. Marks, J&f. 1191(1%7); S.O.GrimmdJ.H.Ambnu.J.Og.~33.2993(1968). =D. W. ABen, B. G. Hutky and M. T. J. Mellow, 1. Ckm. !hc. PC&II II, 1690(1974). ascc e.g., C. Cambilku, P. Sxrtbw and G. Bnm, Ttimhfmn Letters 281(1976);R A. Jooca, S. Nokkco arid titokb Sii. syatk coma’. I, 1% (1977). y. N. hirttbews xnd G. H. B&I, Tehhdmn L&ma 5707 mm. =G. W& and U. Schcolkopf, h. Syn&. Coil. VoL v, 751 (1973). =H. J. Beatmum and B. Arnaoon. Chem. Bw. 95.1513 (1962). ~II. K. Ymv and D. J!ckhxrdt, Z& f&h&i Kbim. 31.35% (l%l): aall. A&r. n,4621 (1962). ‘K. !kbb#$ xnd H. E%u, lkibi#J Ann. 61676 (1%4). =R. A. Jonea xnd M.-A. Tdmct, AusbDL1. &a. 18,903 (1%5). ‘?3. Atsacs. Acfo Chea Scaad. 15,438 (l%l). “F. Ramilw and s. fkaXbowit& 1. org. aem. 12.41 (1957). ‘*S. Trippctt xnd D. M. Wxlker. 1 Ghan. Sot. 1266(l%l). “H. C. van deerPh ud C. J. Pawoaa, Rec. Tmo. chim. 63,701 (1964). %Iiti& prrtcDt 1, 154. 745 (I%6); Glum. AbJtr. 71. p7Ms6 (1969). UP.A.Cbopard,RJ.G.ScarkandP.H.Dwitt,J.OrgChan. 30.1015 (1965). YP.B.Hulbat.EBuediPOmdC.~.Robinson,~.M~C~: 16,72 (1973). ?d. 1. SbeVChUk id A. v. btllbfOV&ii. a tiJ&Ckd Khflll. 34,916 (1964);Ghan. Abrtr. 60.15810 (1961). ma - A&y1 - i - etboxycubonylmetbyki&&eny@oq&xnG was found to have q .p. 17!&1m M..” ma. 172-174l (Poaod: C. 73.6 H. 6.0. Cxk.. ior C&0$‘:& 73.i; H, 5996). m(l - Methyl - 2 - pynoloy@ctbykn&ipbenylpbospborw, Obtk4iflWmtk~pbospboaiumChbfidC.hSd
m.p. 183-184e(Faund: C. n.9; H. 5.8; N, 3.9. CtJIpNOP quirca: C. 78.2: H, 5.8; N, 3.796).
In the cuurse of our study of the thermal decomposition of tbc beWoaroyimethyknephosphoranes,l 1 and 3, it was of interest to disuwer whether there was any dilfereaceintbeekctronkstructuresaadintbepreferred conformations of the isomeric pbospburanea,which would a&t the e5cklKy of their conversion into the heteroarywyw, 2. Ar’.CO.$.Ar’
A$.CrC.A,‘-Ar’.C.CO.Ar’
_
5. d II
ijPh,
Pph,
I
3
2
H- -
R’
R’
0
R'
+PPh,
PPh,
40
4b R’
v-c
0
R’
+P Ph,
R’
O-
-
negligiik interaction between the quaterwy P’ atom and the anoinic O- atom of the chid htterionic sbucture (4) and although at low temperature, structures anakgoustotbeCmemberedring6havebeencon6m~d as intermedhs in the w* synt&sis of alkenes: such stIllctures have little importance in the ground state strum of the acyhethylenephosphoranc3. The equiliium position for the two cunformers, 4 and
H
+PPh,
tk
I’OtdOld
CllClW
barrier
bCtWWl
tk8C
UMl-
f&men should be affect&j oat only by the electronic characterofR’butshouldalsodependupontbedegree of interaction of Rz with the CO group. In particular,an ekctron-withdrawing R2 substhat would be expected to deshbilixe the zwitwionic structures 4b and sb. Similarly, sterk in&action between the aryl substituents .and the triphenylphosphoryl group should Educe the c&wity of the phosphrane system with a consequent destabilixath of the canonical forms 4b and sb. “P Chemical shift data have been accumulated for a widerangeofphmphwsuunpounds9anditisapparent that “P NMR spectroscopy could provide a ~osticpfobeforthes~oftbeinteractionoftheP atom of tbc phosphoranes with the acylmethylene group. However, no systematic survey of the “P NMR spectra of acylmethykae phospboranes has been reported.
Sb R’
R’ w
0 -
PPh,
6
In previous confstudied of acyhethyknepbospboraws 4*5 extensive use has been made of variabktempenwe’HNMRspectrwop~‘aaditis evident that, when R’ # H, the cisoid structure 4 predominates,attln@itkasbu?nlKMdtbattJEbulkof tbeR’substhnta&tstheequiliiposition.’Botb conformers of the formylmethyknephphaae (4 and S;R’-d-H)exhtinequitibriuminaca t:lratioat room tempeMw,&’ but tbe presence of a strongly electron w&drawing sub&u&, R’, produces an increaseintt.terektivec.oecentrationofthefmn8o&fconformer.“Tlle’HNMRdataalsoMicatedthatthreis
The “P NMR cbmical shifts of the simple acylmethykae pbospboranes (PW=CHCOR), presented in Tabk 1, were in accord with previously reported ‘HNMR data for analogous acylmetllylenepbosptmranes~’ and Micated that, with the exception of the formyl compou& only ‘one conformation exists in &uterdloroform and in deuterobenxene. Comparison of the ma&&s of the observed ‘IP CWdShiftsWithpnviouslyrep0rtedvalues for acyiphosplmranes of known conformation7*‘zcon6rms that the wmpowds under inveshgation have the cisoid sbWure4.TbeshkldingeffectontbePatomoftbe YMe% signal
as observai in the UpfMd shift of tbc rmoMllce Compared With the &&cal shifts of the c.or-
responding pbosphonium salts, is compatiile with either the da-pa inhaction between the P atom and the carbanioniC0l0thykmgroupofIr ortbeconjugationof the phosphonium group with tbc enolate anion w-system
J.M.Barr~~~~aulRA.Jowra
1140
Table 1.“P NMRckadcal Mb for acyh&bylenepborpbaraa (Pb,lWHCOR)md the m pborpboaium W&W (l’l&!EgOR) phosphon%lY5 Selt
PtXMphoreUe
R
in C6D6
in CDCl3
Hydrogen
in CDC13
-15.0 -19.1 5
Methyl
-14.8 a
-15.8
-13.6 -20.1 2
1-mthyl-Z-pynolyl
-16.6
-17.2
-22.9
P-Thienyl
-16.9
-17.5
-22.1
2-Fury1
-17.2
-17.8
-22.3
PheIIyl
-17.2 d
-17.9
-22.3 2
5
cleoid fom7 -15.0 p.p.m.; trmuoid form7 -19.1 p.p.o.
c
high field el.gnel due to em1 form.12
a
lit,,13
a
2
lb.,12 -14.7 p.p.m.
lit.,13'14-16.7 p.p.m.
-20.7 p.p.m.
Of~~~~Of~~~~f~~ p&spaorancaill~~f~n?~t4dK: cbmicd shift8 of the corresponding CompWds
measuredindeuterobenxene,arccoMi8tenttia greater cuntriition of the exteadcd conjugated system (4b) to resonance hybrid in the more polar soIve& Such ~eff~~d~e~by~~~~~terochloroform to SpeciiIcally8olvate the ylide through H- bondingwith t& enokte 0 atom. This inteqretation of t& solvent shift Mers from that proposed for the solvent e&t upon the ‘H chemical shifts of the conforImtionauy mobik ethoxycarbonylmethyknephOBpilOraneS’” and for the formyhnethyknepbsphwa~cs;'in which it was sqgestcd that the more polar solvent &Slid the fmdif cxmf0rmah. Them is m evidence from the “PNMR spectra for the presenceof the four-memlzred cyclic structure (6)” in either solvent. ‘l%evariationinthedeshkld@eWtofthearyl Wbstituentupon the phosphorous mlckus of the amyl~~yk~~~~ is small and follows the order:
eon-
of ‘%NMR data for alkoxycarboaylmethykIleylides,“batmaybemtioMl.izedintermsof
freqlleEk8 observed for the a4Wy! CQmpoimda”are also in ageementwithtbe~enokteaaion StrucWe. It~~~~~~~~~ of alkoxycarbonylmethyknepho8payteaepaMyrboraaes is sensitive to thestericbulkofalkylRroops,R’,ontheaubanWc centre.‘&boll&hary1aubstitWnt8tendtosEabitiu:the cisoid rotamer.lo30coMilltent with these obllervations, each a-aryi-a-aroyhnethykne-pho#omne exhii only ooe “P msonance sigual, which, by qalogy with the simpk aroylmethykne =mpounds, we have aftsigned to the &o&f &Mner(Table2). However, the introdWtion of the (betero)aryl sub8tihKntat the a-position of the produceda&a-heteroaroylmethykn tinct de&&@ e&t upon the dbosphorus nucks when the spectra were measured in Cm3. The greatest e&t was observed upon the aeon of the 2--l 7 (l.tW.9ppm), whi!st the phosphorus nucleus of phenyl> 2-furyl> 2-thkllyl> l-methyl-2-pyrrolyl. e 2-thtenyl and l-methyl-2-pyrrolyl derivatives was deahklded to a smaller extent (0.7This order approximatesto the expected inductiveekc- 0.9ppm). The smalkat e&t was observed for the atron_witbclrawiaepropertiesoftbearyl~andistbc p&nyl compou& (0.2o~ppm). In contrast to these invcnic of theirfrle-mdcekctropdoaatipgabili?y.TEis obsmations, the int&lChoS Of 8 @Cell, 2-thimlylOf ~~$~~~~~~~I~~~ l-~~~2~~lyl groupat the a-positionof the benzoylP-CL’0 plane, as Scsted by X-ray measureme& in rn~~e~~~p~~~~~w~ the solid state for an8k#oua compom&U pcr5%a in the 2-fury1derivative resonated at lower &Id. Sohlt&.BothtbeiMhKtiWettcctandtheClDSS-i%l!Mokudarmodelsahowthf&forthecMdro~r, jugatio~oftheCOoroupwiththeary1ring~the lleitkbetCfOCyCiiCliOgCanlkilltb8S8Olephlle~tbC c&amonic ceotre have a de&&G& effect up00 the bC-6 ay8tcm ad the deslkiddhg effeds Can be ~~~~~~~ch~~~~~ . . ~*~Cff~~~~ ~~~ofa~~~~d~-p~~~ ~~of~p~~~~~~~ ~~k~~rex~~~~~~~*H~ +system,asareaultofthei$ictiveekctron-with-. shiftsofthemethyk.neprotonwiththechaoSoftbe aroyl &atitumt. However, the small ransc of the drawal by the a-beterorrryl s&Utuent~~.“~ The “achemical shift8 (a 4.05-4.38ppm) Micated that the wbatituent effect” was ksa regular, when the spectra overrid& conjugative inter&on for the simpk acyl- were measured in S but.ingene&a methyknepho@mmes is bed represented by Ib. This &shkunge&twasobnervedforallP-arylder+vaconclusion differs from that previoosly reached from a tives, with the exe&on of the a-(2*furyl)compoo& It
1141
Tabk 2 “P chmid
A2
difts for (a+royl-a~P’iph~
-
in
-1
phenyl n
I,
n
II 2-Thienyl 11
in
C6D6
-16.0
-15.0
1-t4thy1-2-pyrro1y1 -16.8
-16.2
P-Thiemyl
-17.1
-16.5
2-Fury1
-17.5
-16.8
1-Mehyl-2-pyrrolyl phanyl n 1-Methy1-2-Py7m1y1 II
CDC13
-16.7
_
-17.4
-16.9
2-Thhlyl
-17.7
-17.8
2-Fury1
-18.1
phenyl
-16.9
1-Methyl-2-pyrrolyl -17.3
-16.25
n
P-Thienyl
-17.7
-1723
1,
2-Yuryl
-18.7
phenyl
-17.6
-17.2
I,
1-Methy1-2-pymo1y1
-18.4
-17.8
1,
2-Thienyl
-10.0
-18.7
"
2-Fury1
-19.1
-18.8
2-Fury1
Tabk 3."P c.&cmidabifts ofa-selyllada-benzoyhwth~
(Ph,P4!Rz~~R’)
LJ31Pillctx.il 3
AC
m
H
-14.8
0
ne
acety1
-16.6
-2.0
24
1-mcthy1-2-pyrroloyl
-17.0
-2.2
M!
2-thewy1
-17.9
-3.1
Me
P-furoyl
-17.0
-3.0
m
b==Vl
-18.8
-4.0
ph
H
-17.2
0
Ph
acetyl
-18.8
-1.6
Ptl
1-m8thy1-2-pJmro10y1
-17.7
-0.5
Ph
2-themoy1
-19.0
-1.8
Ph
P-fllroyl
-19.1
-1.9
Ph
WY1
-19.0
-1.8
5
A
-
8 (R2-acyl)-8
(R*-i#)
1142
J.MBilnTAlNaDdRA.JoNss
thermal fragmentation of the a-henxoyl-a-beteroaroylmethyknepbospboranes to give the l-ixeteroaroyl-2pheqykthynes (Ar-CO-CxCPh).’The larger and more variable “a-acyl effect” rest&& from the inboduction about the C-C bond of the b%=O system wouldallow of heteroaroyl groups at the a-position of the acetyla greater degree of mesomeric interaction with tbe methyknephospboratk indicated a greater degree of heteroaryl ring!& conjugation of the heteroaroyl group with the carThe introductionof a second a-acyl substituentto give banioniccentre and that both (7b, R=Me)and (7~.R-Me) the a,adiacylmethyknephosphoranes had a signi6caat are impmtant canonical sbuctmes. This resonance deshidding effect upon tbe pbusphorus nucleus (Table stabilixatb is retkcted in the almostequivalentyields of 3). The “a-acyl effect” had a greater intluenceupon the tbe l&eMoarylbut-I-yn-3-ones(Ar-C&-CO-Me)and l“P chemical shift of the a-acetylmethykne- he&oarylbut-3-yn-lunar (ArCOGX!-Me), obtabad phosphoranes (2.0-4.Oppm), compared with the a- upon thermal fragmentation of the u-acetylsbenxeylmethyknephosphoranes (0.5-1.9ppm). By heteroaroylmethyknepbospberanes.’ analogy with tbe preferred conformation of tbe ‘free” similarly, the downtkkl shift of tbe “P resonance anion of @diketones,~ the a,adiacylmethykne- signals, observed upon the formation of the a-acyl phosphoranes would he expected to adopt the con- derivatives of ethoxcarbonylmethyk@rorane, can he formation (7). An inspection of mokcular models, attriitedtoapreaterdekcati&onofthecarbanionic however, indicated that only one acyl group could con- charge. Hence, ahbough steric hi&ance prevents jugate effectively with tlk carbonioniccentre. copkbtyofhoththeRgroupandtbeestersubst&nt is probable that. with the des&Gng effect of the deuterobenxene upon canonical structure 4b. the ylide structure 4a tEc4unesmore importantand partialrotation
P A
Ph,L
\
with the bC-6 system, aumnkal stnmture @e) wouldbeexpectedtoprovi&amajorcontrkutkntotJk resonant hybrid. By analogy with chemical shifts observed with the simpk aroylmethykne compounds (Table 1). it is apparent that the aryl groups Raveessentially only an inductbe ekctron-withdrawingintluence on the system and the variationof tbe “P chemicalshift withtbechangeinthearylgroupisnegligiieflabk4).
8
-R
+
-
/c--R
PhsP-C+C_Ar
fi-Ar
b-
0
70
7b
+ Ph ,P-C
?//C--R \
5-A’
Ph,P+-C
0 7c The
ahost constant and small “4-acyl effect” obser-
/ \
Ph,?-
$-OE’
\\
$-OE’ 0-
aa
ab
8’ Ph a-6
Cd’-’ \
E-OE’ 0
ec
for actboxycarbonylmeU~yIeWr+heoykb&i~~(Ph,l’=CRC4Et)
&ifts
631P in clxx3
AS
A-
0
+3.3
b
n
-17.g
acetyl
-18.1
-1.1
-3.3
benzoyl
-19.4
-2.4
-2.2
2-furoyl
-19.4
-2.4
-2.2
2-thwyl
-19.4
-2.4
-2.5
1-methyl-2-pyrroloyl
-19.4
-2.4
-2.8
a
A
a
A -
r
C-R
/ C
0
ved for the benxoylmethyknep~s and the relatively constant value for the “P chemical shifts of these derivativesis compatiik with(7~.R = Ph) beii the more important canonical structure. Tbe “a-acyl deshklding e&t” for t&se. compounds consequently arises from the inductive electron-withdrawingeffect of the twisted non-conjugating heteroaroyl group. This postulate is in accord with the observed preferential Tabk 4. ,‘P cbmical
0
i? C-R
-
6 @-a~yl)-6
(R-H)
b (Ph3P-CR.co2Et)-6 (P+~~PICHR)
lit.,24 -16.8 p.p.m.
Pbosphonium s&s and pbosp&ranes-vI’
1143
(a - 2 - Fwyt - a - 2 - t~~mcthyl~)~~y~~sphomnr (!M%),m.p. l%-lP, dcc. (Fold: c, 74.0; H, 4.8. C2sH*rozPS
-AL
“PNbfRspxtrawc~-crux~daiusingrVariimXL-100spcc-
(!i#%), IX&.K&i%’ @oun& C, fi0.s; H, s& N, 3.2. C.,H,sNOP reauina: C. 81.0: H, 5.7: N. 3.1%J. (a - Bau@ - i - 2 - jWyJGd#&~~~~~SphO~ (99%). qp. 19219y (pouad: C. 8O.R H, 4.9. t&H&P nquirea: C. 89.7; H, 5.2%). (a - Be~~zoyl- a - 2 - th&nytmethyk)t&riplSarrblkorplronuu (!H%),m.p. 2tNP(Found: C, 77.7; H, 5.2. CJ&OPS nqti: C, 77.s; H, 5.0%). (a - 2 - ?Moyi - 0 - 2 - t~y~~~)~~~pwp&omw @f%)* m.p. 188-1W Wlmdz C, 71.4 w, 4.6. C,&OPS rcqmrcs: C, 71.8; H. 4.5%). (4 - (1 - Me&f - 2 - pydyf) - a - 2 - Ml&mcthyt~eWphaWho~pho~e (71%), m.p. 216218” (Found C, 74.9: H. 5.6: N. 27. CmHdJOPS rcdcs: C, 74.7: H, 52; N, peppy-
pho@trmhm~ chloride. W.8~
80%) m.p. 22%W
Wundi
C,
68.1: H, 4.9. C&&lOPS re@irea: c, 68.2; 4.8%). (l-Mtt&~-2-pynv&yf)h&J~jdpho#phaJIimm chlo?fdsz lbalk (9.7& 0.12moQ and 2,b&id& (12&g, 0:12mol) in CHCh WOmlI were added over a wrkwf of ca 1Jltr to a Je~iqt-sobJ of &loNWyl cbkridc 03.6 & 0.12mol) in CHClJ (aoJlli& The JDixtmt wM rduxed for 2 In ad tbc solveot ~v~~n~~r~~~~~vea~wti~ wucoaeclrdrPdwadwxlwitbctbcr(soall).TbscoalbiictJlcr extmcts were wasbed successively witb 3NHCl(2x3Oml) and
H, j3f N, 53, C&&0$ &ire& C, R.5; H, 54; N, 3.1%). (~-(1-~~~-2-p~~-a-2-t~~h~~)t~~~&o&oruiw 181461, m.n Wdec. (Pou& C. 74.k H. S1: N. 2.8% &I&, NOPS mquircs: C, 74.7; H; 5.2; N, 3.0%); ht - (1 - kthti - 2 - DYJW&fi - (I - (1 - m&Y/ - 2 -
wrta (5 x loom& dried (a&So& and cvaporatd to give a ye&w oil. wbkb on tdumtion witb pctrokum& (40-W) s&d&xl to give 2doraaMyipysYok (12gI 65%)*m.p. [email protected] m.p. 474. Tbc 2~~~~ (~~-0.~~) was converted into (l-mUhyi-2-py~~~~y~~~~ chlor& (11p. si%), m.p. 238-2391(F~~LI&C, 712 H. 5-S: N, 3.4. C&,ClNOP requires: C, 715: Ii, 5.5: N, 33%) by a procubue adogoua to tbat de&xii above for thesynthcs~of the tbiopben Jdogtlc. BqJadM of Phosp&wuJW3*The known acyllldykJmpboqoWwcre~ffomtbceornspo~~~ pbomtJmdtsbyo=tbodsdcscAdintbcWaturc. ~rn.~w~~~nt~~~~~~ andfRaad’HNMRspccaaldatawerccomp&kwitbti~~ cxpixted vahbs. TbcbitbatowreportedwmpoundawenpJepadbytbc f~~~~~~ (a-~~~-a~~~~~~~~ea The appm&ak arylmeiJlyltii&n~llium chloride (0.03mo9 was a&id witb stirr& to freshly prqmred NaOEt (0.03mol) in bmtzcne (IWml) under Nt.” Tbe mixture was stinsdfor4SmiaItU*arwltbeE(oHwarnmovedbyrrzeotropit dktiuon. The aaofoDJiatc arovl CbloJide Io.o1slDon in
- a - (I- methyi - 2 - pym~lyl)muh@Jc)t~$~he~~ylC, 80.$ H, ti& N, 2.9. C&&OP requires: C, 81.0; H, S-7; N, 3.f%). (a - 2 - M - a - 2 - thawytmethylaw)trfpktnytpkosphonmc (5’4%) m-p. 189’. dec. (PopDd: C, 76.6; H, 4.9. C&i&P nsuirca: c, nR; H, 4.9%). (0 - 2 - Bmyf - a - 2 - !Matykth~)t~htnyfphoap~~ (9246)m.p. 177~1W (Founds C, 74.2: H, 4.5. C2JI&FS phoapkomne ilOO%),rm.p. 1225-1230(PO&: C, 70.& ir, j.0. Jequins: c. 74.3; H, 4.7%). C&H&d’s nauires: C. 70.7: H. S.l%b (a - 2 - &U$ - a - (1 - mdyf - 2 - $y~y~m~~~t~~~~~ (73561, m-p. 232-233”(pourd: c. 77.2: H, 5.3; N, 3.5. &&N&P reqircs: C, 77.3; H, S.4: N, 3.1%).
1144
J.M.B~~~~AIN~IMIR.A.J~
(a - BenwyI - a - (1- InerhH - 2 - pymdo~)mJthyiaw)triphalyl(1 - Methyl - 2 - pylroky0mctbyka?fIipbenylpboxpbafw (1.14& 0.003mol) xDd balxok Mbydl+k (1.11. 0.005ID00iu CHCI, (15 ml) were realxed for 12hr. Tbc sdvcot w8arcmovcdaadtbcfeaidudoilaNctedwitbpctrokumetber (b.p. 6M#r, 5 x I5 ml) to nmove tbc cxcca8 knxuic mlbydrik. Tihntion of the residue with dktbyl ether: bexane (1: I) gave (abaud - a - (1 - rndhll - 2 - PwWWWWWWphosphotw (136g, !I3%), q.p. 211-214n(FoundzC.ltO.l. H. 5.4 N, 27. &&N&P rcquirw C, 79.8. H. 5.3; N. 29%). Pllospikomnr
A&no~a~&--We tbxnk Dr. R. K. Hti tbe”Pp.oberodMr.P.HxylettforY~in~tbe”P rcsonxnce w J.M.B. g&fully akwwk&s xll S.R.C. lBFiiatelmIlCc ggarlt
for tbc loan of tbc receipt of
‘PutV.J.M.BritbinPadRA.Jwes.I.CikanRtkaubmittcd for pubuion. Q. J. Bcstnmnn and 1. P. Snyder, 1. Am. Chun. Sot. 89.39% (1967). ‘H. L Zdi~a, J. P. Snyder and H. J. Bestnmnn. Tern&&~ JiurerJ 3313(1970). ‘J. P. Say&r xnd H. 1. Beatmum, Ibid 3317(1970). ‘I. I? Who xnd J. C. T&by, &id. 3769(1970). ‘IA. L. FiBeux-Bkndmrd aad M. G. J. AMio. C.R Acad Sci, Pad8 27#c, 1747(1970). ‘Cc.J. Devtiu ami B. J. Walker, Tdmkdmn L4#clv4323(1971); Teh&edm 1.3501(1972). ‘S. Trippat, Pm AppLCkm. 9.‘255(1954). ‘see, eg, G. Mxrvd. Annual Repott~ of NMR Spectrurapy (Edited by E. F. Mooney), Vol. 5B. Academic Resr. Ladon (wn). xnd s&c&lilt P&did Rqolt3 on orpMoprkosprkons Chcmlstty,vol.3 14 The chemical !3ockty, London (1970-n). “J. P. Snyder, Tdmhedtm L&ma 215 (1971). “cf. CLH. Binun xnd C. N. Matthews, Chew Comma137(1967); E. Vukjr xnd K. A. J. S&k. I. Aa Cha &c. 95.5778 (1973): E. Vedejs. K. A. 1. Snobk and P. L. F@m, 1. Otx. c&em. 3& 1178(1973). ‘15. A. Nermeyaaov, S. T. Bermxn, P. V. Petrovxkii and V. I. Robaa, M Acad Nauk SSSR 22#, 1372(1975):Chea Abrtr. a 138no (1975). “F. Ram&, 0. P. Madau sod C. P. Smith, Tetmhedm 22,567 (1966). ‘+Ibchieberv~uerecordcdbyA.J.SperkkladK.W.Raas.I.
Am.chalLsor.I,279o(1963)i8tbxtofsampkcoa~ by the pboapbonium sdt. “I’. S. Stepben. 1. Chat. Sot. 5658(1%5); A. J. Spexixk awl K. w.Rlt&J.AJn.aa&c.87,5603(1965). ‘6. A. Gray, Ibid %,7736 (1973). “J. M. Brittxin, Ph.D. Tkais. Uaivaity of Exat Anglk (1977). “See P. J. Taylor, &ecbuchia AC& 34,115 (1978). ‘q. Zcligcz, J. P. Snyder and H. J. Butmano, Tetmhdmn I.‘drm 21% (1969). =D. M. Crauae, A. T. Webman xnd E. E. Schweixcq Chem. &mm. 866 (1968). “See S. 0. Grim, W. McParkw and T. J. Marks, J&f. 1191(1%7); S.O.GrimmdJ.H.Ambnu.J.Og.~33.2993(1968). =D. W. ABen, B. G. Hutky and M. T. J. Mellow, 1. Ckm. !hc. PC&II II, 1690(1974). ascc e.g., C. Cambilku, P. Sxrtbw and G. Bnm, Ttimhfmn Letters 281(1976);R A. Jooca, S. Nokkco arid titokb Sii. syatk coma’. I, 1% (1977). y. N. hirttbews xnd G. H. B&I, Tehhdmn L&ma 5707 mm. =G. W& and U. Schcolkopf, h. Syn&. Coil. VoL v, 751 (1973). =H. J. Beatmum and B. Arnaoon. Chem. Bw. 95.1513 (1962). ~II. K. Ymv and D. J!ckhxrdt, Z& f&h&i Kbim. 31.35% (l%l): aall. A&r. n,4621 (1962). ‘K. !kbb#$ xnd H. E%u, lkibi#J Ann. 61676 (1%4). =R. A. Jonea xnd M.-A. Tdmct, AusbDL1. &a. 18,903 (1%5). ‘?3. Atsacs. Acfo Chea Scaad. 15,438 (l%l). “F. Ramilw and s. fkaXbowit& 1. org. aem. 12.41 (1957). ‘*S. Trippctt xnd D. M. Wxlker. 1 Ghan. Sot. 1266(l%l). “H. C. van deerPh ud C. J. Pawoaa, Rec. Tmo. chim. 63,701 (1964). %Iiti& prrtcDt 1, 154. 745 (I%6); Glum. AbJtr. 71. p7Ms6 (1969). UP.A.Cbopard,RJ.G.ScarkandP.H.Dwitt,J.OrgChan. 30.1015 (1965). YP.B.Hulbat.EBuediPOmdC.~.Robinson,~.M~C~: 16,72 (1973). ?d. 1. SbeVChUk id A. v. btllbfOV&ii. a tiJ&Ckd Khflll. 34,916 (1964);Ghan. Abrtr. 60.15810 (1961). ma - A&y1 - i - etboxycubonylmetbyki&&eny@oq&xnG was found to have q .p. 17!&1m M..” ma. 172-174l (Poaod: C. 73.6 H. 6.0. Cxk.. ior C&0$‘:& 73.i; H, 5996). m(l - Methyl - 2 - pynoloy@ctbykn&ipbenylpbospborw, Obtk4iflWmtk~pbospboaiumChbfidC.hSd
m.p. 183-184e(Faund: C. n.9; H. 5.8; N, 3.9. CtJIpNOP quirca: C. 78.2: H, 5.8; N, 3.796).