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Synthesis of carbo- and heterocyclic compounds by radical-initiated cyclizations of propargylsilanes
Temzhedron Lrtrers, Vol. 35, No. 32, pp. 5853-5856, 1994 Else&r Science Ltd Rinted in Great Britain oo404039194 s7.oo+o.w
OCMO-4039(94)01170-2
Synthesis .of Garbo- and Heterocyclic Compounds Cyclizations
of Propargylsilanes
DieterShin&a. RterG. Jonesb, ah8titUt Air c&mi8chc
by RadicaMnitiated
Kerstin Obie~ya
dcr Technisci~a Univer8iM B raumchweig, Hagenting 30, D-38106 Braumchweig, &many
chernie
bInstitutfitrAn~8cheundAMl Hageeg
beCheu&de~TechnischenUniversitgtBraumchweig, 3Pc, D-38 106 Braunschweig, Germany
Abstract: Propargylic silanes of type 2,4,9.11. and 13 undergo smooth cyclization in refluxing benzene and in the rescnce of AIBN and tributyltin hydride. Ring closure of carbocycles and also of 5 and 6memhemd K hetcmcyclic ring8 i8 achieved in high chemical yields. Radical cyclizations
have proved
to be valuable
8yIIthetiC method8 of forming cyclic or polycyclic
frameworks. 1,2 In this letter we wish to report a novel method of constructing either carbo- or hetezocyclic skeletons by a radical cyclization - initiated by AIBN in the presence of ixibutyltin hydride - ofpropargylic
silanes.
Ketones of type 2 or 4 can be easily obtained by a tandem reaction of the copper-catalyzed functional&d
addition of a
Grignard magent to cyclobexenone 1 and in situ quenching with NBS.3 0
0 1 _
2.
Bmd--,
CuBr - Sldeo c
NBS
1 The Carbocyclic ketone8 2 and 4 can be directly cyclized witi AIBN and tributyltin hydride to give the &sired &cyclic ketones a8 a ca 6 : 1 ratio of S
of tbe resulting ally1 silanes 3 (34%). and 5 (50%); the Z
isomersprtdormnatt?
2
AIBN,
Bu#nH
5853
5854
5
4 -llBesehicycliccampounds
containthe synthetically
propargyl s&me. EspecUy
exocyclic ally&
useful allylsilam as a mult of the radical cyclization of the
silalles are not easy obtail@
because only cyclic ketones can be
used in these particular Wittig rem3ionsP Allylsilanes
can be regioselectively
functionalixed compounds
transformed
in the presence
of electrophiles
which demonstrates the high potential of these compomds
The next systems we examined we= 0-heterocyclic
to a wide variety of in organic synthcs@8
compoundsof type 10 and 12. The m
9 and 11
for this operation can be prepared by one-pot procedures with the enones in the presence of the unsaturated alcohols and NBS.9
1
2,
NBS
-
TMSCN
2. lMSCHpOTt Sime, However,
in order to synthesize
the desired precursors for the heterocyclic
carbonyl group as silylated cyanohydrins
9 and 11. 10 These compounds
conditions in quantitative yield to give the desired 0-hetemcycles diastereo~
10 (98%)
series we had to protect the
cychzed smoothly under standard and 12 (>98%) both in a ratio of
of about 4 : 1, again favoring the Z-isomer of the allylic silane.3 The structure of compound 10
@-isomer) has been confhmed
by X-ray analysis.l1*12
sws
FQure.MolccularstNctllrcof
1ointheclyml
Thisdramatic influence of the silylated cyanohydrin could be a result of &stabilization nitrile group or by the &oxygen
of the radical by the
atoms.13*14
12
11
Finally we have tested compound 13inorder toform the synthetically useful oxo-bicycle-octane
system 14,
which we obtained in 40% yield, again favoring the Z-isomer of the ally1 silane in a ratio of about 4 : 1.3915
AWN,
BuaSn H
14
5856
In summary, we have demonstratedthat radicalcycIiaation8of poprgylsilancsareapow&tlmcthodof constructingc&o-
and hetuo-bicyclic systema that contain the syntheticallyuseful allylic SiIaneS.The
allylsilanesobtainedcanbeaansfarmbd~aavvarietyafsystcmqbyknawn~.
The extensionof
thismtthodtoodKIheterocyCltsand~S~is~~y~~inoUrlaboratorC8.
Acknowledgment.
This WC& was suppated by the tbc Fonds dcr CbemischenIndustric.We ate indebted
to the S&ring AG, Berlin,for generousgifts ofc~s.
Mr. A. Weinkaufpmvidcd tcchnicaIaaaiatanccin
the x-ray saucture&tcrmiMuon.
References and Notes
ofCarbon-Carbort
1.
~=~Bi&&rZs
::
Sunk. 0.; M&Ii, R. J. Am. Chcm. Sot. 1983.ZO5. 3720, Allnewcanpoundsgavespecualaudanalyticals~
in Organic Synthesis. Formation
lb&‘.
Ekqaxmn
PIWS,
dataconsiatcntwlthtbcaaaigntd
SUUClUItX. Fleming. 1.;Paterson,I. Synthesis 1979. 447.
f: f: i* 16. 11.
Fleming. I.; Dunogues, J. Organic Reactions 1989.37. 57. Salauai,H. Pureand 1. them. 1982.54, 1. Majetich. G. in Theory cmdilpphcqtion: T. Hudlicky, Rd.. JaiPress, Inc. Greenwich. CT, 1989. 173. Schinzer, D. Synthesis 1988,263. Dulccrc, J. P.; Rodriguez J.; Satuclll. M. Tetrahedron ktt. l!B7.28,u)o9. Groutaa,W. C.; Felkcr, D. Synthesis 1960,861. Standard procedure: To a solutionof compound9 (157mg. 0.39mmol) in 25ml of benzenewas addedaarciofAIBNanddre~~washeatedtonflux.Asolutionoftributyltinhydride(134mg. 0_46Pm&ol)waosddedoverlhwitha~~pumpandthe~~waprefluxedforanadditlonal3 b’IbemixturewaspouredintoasaaaatedsolutionofNaF,andtheaganiclayerwasdried?ver MgSO4. The crutIeproductwas flash cluomatogcaphcdwithpentan&?i&yl ether w&:fza ofcompound 10~isomer)and34mgofcompound lO(Fi-isomer).S~ 10 (Z-is-r): 1H-NMR (CDCl3). (400 MHu): 0.01 (s. 9 H); 0.19 (s, 9 H); 1.33 (m. 2 H); 1.63 (m, 2 H); 1.88 (tn. 2 H); 2.096 (m, 2 H); 2.73 (dd, 1 Ii, J = 2.73 Hz, J = 23.62 Hz); 4.01-3.89 (m, 1 H), 4.25 (m, 2 I-I); 5.57 (dtr, lH, J = 8.66 Hz, J = 14.63 Hz). 13CNMR (CDCl3), (109 MHz): 136.35; 123.27; 119.89; 76.38; 72.50; 70.98; 51.80; 38.17; 27.08; 20.49; 14.78; O.a7; -1.82.
12.
Crystal data for lo:triclinic, PI, u = 1151.2(3), b = 1385.5(3), c = 1403.3(3) pm, a = 70.83(2), I3=
ii:
88.84(2), 7 = 77.40(2) o (at -130 oC), Z = 2. The structurewas retinedon F2 (progtam SHRLKL-93, GM. Sheld&k, Univ. of G&tingen) to wR(F2) 0.130, conventionalR(F) 0.046 for 7251 rtfloaionsto~5oo(Mo~~).).Fulldttailrofthtsrructurt~~haveb#ndbpcwictdat theFa&i&rmationszcntnun Karkuuhc,GcaellschaftfttrWissenachaftlich-t Information n, Germany.Any requestfor thismat&al shouldquote a full n&I-I,D-76344 Eggenstein-v litcratumcIuuionandtbcmfcmnccnumbc7C!SD4OO9O6. Beckwlth, A. L. J. Chem. Sot. Rev. 1993, 143. y8T H. G.; Susunaun,R.; Gieac. B.; Rtickart,B.; G&h&c%, K. S. C&m. Ber. 19!M,Z23,
15.
RajauBabu. T. V. J. Org. Chem.
(Received
1988.53.4522.
in Germany 29 May 1994; accepted
16 June 1994)
OCMO-4039(94)01170-2
Synthesis .of Garbo- and Heterocyclic Compounds Cyclizations
of Propargylsilanes
DieterShin&a. RterG. Jonesb, ah8titUt Air c&mi8chc
by RadicaMnitiated
Kerstin Obie~ya
dcr Technisci~a Univer8iM B raumchweig, Hagenting 30, D-38106 Braumchweig, &many
chernie
bInstitutfitrAn~8cheundAMl Hageeg
beCheu&de~TechnischenUniversitgtBraumchweig, 3Pc, D-38 106 Braunschweig, Germany
Abstract: Propargylic silanes of type 2,4,9.11. and 13 undergo smooth cyclization in refluxing benzene and in the rescnce of AIBN and tributyltin hydride. Ring closure of carbocycles and also of 5 and 6memhemd K hetcmcyclic ring8 i8 achieved in high chemical yields. Radical cyclizations
have proved
to be valuable
8yIIthetiC method8 of forming cyclic or polycyclic
frameworks. 1,2 In this letter we wish to report a novel method of constructing either carbo- or hetezocyclic skeletons by a radical cyclization - initiated by AIBN in the presence of ixibutyltin hydride - ofpropargylic
silanes.
Ketones of type 2 or 4 can be easily obtained by a tandem reaction of the copper-catalyzed functional&d
addition of a
Grignard magent to cyclobexenone 1 and in situ quenching with NBS.3 0
0 1 _
2.
Bmd--,
CuBr - Sldeo c
NBS
1 The Carbocyclic ketone8 2 and 4 can be directly cyclized witi AIBN and tributyltin hydride to give the &sired &cyclic ketones a8 a ca 6 : 1 ratio of S
of tbe resulting ally1 silanes 3 (34%). and 5 (50%); the Z
isomersprtdormnatt?
2
AIBN,
Bu#nH
5853
5854
5
4 -llBesehicycliccampounds
containthe synthetically
propargyl s&me. EspecUy
exocyclic ally&
useful allylsilam as a mult of the radical cyclization of the
silalles are not easy obtail@
because only cyclic ketones can be
used in these particular Wittig rem3ionsP Allylsilanes
can be regioselectively
functionalixed compounds
transformed
in the presence
of electrophiles
which demonstrates the high potential of these compomds
The next systems we examined we= 0-heterocyclic
to a wide variety of in organic synthcs@8
compoundsof type 10 and 12. The m
9 and 11
for this operation can be prepared by one-pot procedures with the enones in the presence of the unsaturated alcohols and NBS.9
1
2,
NBS
-
TMSCN
2. lMSCHpOTt Sime, However,
in order to synthesize
the desired precursors for the heterocyclic
carbonyl group as silylated cyanohydrins
9 and 11. 10 These compounds
conditions in quantitative yield to give the desired 0-hetemcycles diastereo~
10 (98%)
series we had to protect the
cychzed smoothly under standard and 12 (>98%) both in a ratio of
of about 4 : 1, again favoring the Z-isomer of the allylic silane.3 The structure of compound 10
@-isomer) has been confhmed
by X-ray analysis.l1*12
sws
FQure.MolccularstNctllrcof
1ointheclyml
Thisdramatic influence of the silylated cyanohydrin could be a result of &stabilization nitrile group or by the &oxygen
of the radical by the
atoms.13*14
12
11
Finally we have tested compound 13inorder toform the synthetically useful oxo-bicycle-octane
system 14,
which we obtained in 40% yield, again favoring the Z-isomer of the ally1 silane in a ratio of about 4 : 1.3915
AWN,
BuaSn H
14
5856
In summary, we have demonstratedthat radicalcycIiaation8of poprgylsilancsareapow&tlmcthodof constructingc&o-
and hetuo-bicyclic systema that contain the syntheticallyuseful allylic SiIaneS.The
allylsilanesobtainedcanbeaansfarmbd~aavvarietyafsystcmqbyknawn~.
The extensionof
thismtthodtoodKIheterocyCltsand~S~is~~y~~inoUrlaboratorC8.
Acknowledgment.
This WC& was suppated by the tbc Fonds dcr CbemischenIndustric.We ate indebted
to the S&ring AG, Berlin,for generousgifts ofc~s.
Mr. A. Weinkaufpmvidcd tcchnicaIaaaiatanccin
the x-ray saucture&tcrmiMuon.
References and Notes
ofCarbon-Carbort
1.
~=~Bi&&rZs
::
Sunk. 0.; M&Ii, R. J. Am. Chcm. Sot. 1983.ZO5. 3720, Allnewcanpoundsgavespecualaudanalyticals~
in Organic Synthesis. Formation
lb&‘.
Ekqaxmn
PIWS,
dataconsiatcntwlthtbcaaaigntd
SUUClUItX. Fleming. 1.;Paterson,I. Synthesis 1979. 447.
f: f: i* 16. 11.
Fleming. I.; Dunogues, J. Organic Reactions 1989.37. 57. Salauai,H. Pureand 1. them. 1982.54, 1. Majetich. G. in Theory cmdilpphcqtion: T. Hudlicky, Rd.. JaiPress, Inc. Greenwich. CT, 1989. 173. Schinzer, D. Synthesis 1988,263. Dulccrc, J. P.; Rodriguez J.; Satuclll. M. Tetrahedron ktt. l!B7.28,u)o9. Groutaa,W. C.; Felkcr, D. Synthesis 1960,861. Standard procedure: To a solutionof compound9 (157mg. 0.39mmol) in 25ml of benzenewas addedaarciofAIBNanddre~~washeatedtonflux.Asolutionoftributyltinhydride(134mg. 0_46Pm&ol)waosddedoverlhwitha~~pumpandthe~~waprefluxedforanadditlonal3 b’IbemixturewaspouredintoasaaaatedsolutionofNaF,andtheaganiclayerwasdried?ver MgSO4. The crutIeproductwas flash cluomatogcaphcdwithpentan&?i&yl ether w&:fza ofcompound 10~isomer)and34mgofcompound lO(Fi-isomer).S~ 10 (Z-is-r): 1H-NMR (CDCl3). (400 MHu): 0.01 (s. 9 H); 0.19 (s, 9 H); 1.33 (m. 2 H); 1.63 (m, 2 H); 1.88 (tn. 2 H); 2.096 (m, 2 H); 2.73 (dd, 1 Ii, J = 2.73 Hz, J = 23.62 Hz); 4.01-3.89 (m, 1 H), 4.25 (m, 2 I-I); 5.57 (dtr, lH, J = 8.66 Hz, J = 14.63 Hz). 13CNMR (CDCl3), (109 MHz): 136.35; 123.27; 119.89; 76.38; 72.50; 70.98; 51.80; 38.17; 27.08; 20.49; 14.78; O.a7; -1.82.
12.
Crystal data for lo:triclinic, PI, u = 1151.2(3), b = 1385.5(3), c = 1403.3(3) pm, a = 70.83(2), I3=
ii:
88.84(2), 7 = 77.40(2) o (at -130 oC), Z = 2. The structurewas retinedon F2 (progtam SHRLKL-93, GM. Sheld&k, Univ. of G&tingen) to wR(F2) 0.130, conventionalR(F) 0.046 for 7251 rtfloaionsto~5oo(Mo~~).).Fulldttailrofthtsrructurt~~haveb#ndbpcwictdat theFa&i&rmationszcntnun Karkuuhc,GcaellschaftfttrWissenachaftlich-t Information n, Germany.Any requestfor thismat&al shouldquote a full n&I-I,D-76344 Eggenstein-v litcratumcIuuionandtbcmfcmnccnumbc7C!SD4OO9O6. Beckwlth, A. L. J. Chem. Sot. Rev. 1993, 143. y8T H. G.; Susunaun,R.; Gieac. B.; Rtickart,B.; G&h&c%, K. S. C&m. Ber. 19!M,Z23,
15.
RajauBabu. T. V. J. Org. Chem.
(Received
1988.53.4522.
in Germany 29 May 1994; accepted
16 June 1994)