The structures and chemistrty of isobacteriochlorins from Desulphovibrio gigas

Tetrahedron Letters Xo. 25, pp 2213 - 2316, 1977. Pergamon Press. Printed in Great Britain.

AlanR.Battersby*,

KeithJaws,Edward

kLxmald, John A. F&inson and Howard R. km+?.+,

+Departmentof Biochenkstzy, Imperial College, University of k&on,

London, U.K.

(Received in UK 3 Mqy 1977; accepted for publication 16 May 1977)

Sirohydroohlorin,thereatal-free formoftheprostkticgroup franseveralsulphite redu1 , wassh3wnbySiegelandKaminetal -2tobeanoctacarb3xylicisoba&3ric&lorin

cingbaoteria

They suggested (a) a structure foriti.nvolvingC-methylation at C-12

ketiahydrwx@yrin).

and C-li of urqorphyriwII1

(Ixltreoognised that other isawrs would fit) and (b) that siro-

hydmohlorin (or a relatix) might be on the biosynthetic pathway to vitamin B12. Our interestinthebiosynthesisofthisvitmin grow

fromksulplmvibrio

gigas.

31e3us

toisolate then&al-frespmsthetic

Sonicationoftheoells

andchranatographyon~oellulo6e

Et

Et CO$.4c C02Mc

CO2 Me

(1)

COZMe

gavedesulphoviridin frxanv&-khthemtal-freeprostbetic withmkhanol-H2SOq

gave asmallquantityof

(3)

(2)

sir+&o&l

2213

groupwas released.

Esterifioaticm

orinootamethylesterbutminlya

2214

No. 25

llKlIXDlactane;

the two esterswsre separatedby h.p.1.c.*.

AlltheprGpertiesoftheformer

and F.D. IIXSS (u.v.-visible spectnm, fluorescence,chramtography)matchthosereportedl'* spectratletry confirmedMt 974. Furtherwork is neededbeforethe above r~~~kably specificisolationof mlactcne

is

lmderstooabut,inportant1y,wefindthatoxidativeconversicnofsirchydrochlorin andofits ester(l)intotheNrxlo~

(2) canbeachievdon

isolatedmaterials. structurdlknowledge

derivedfran the nwdactcne (21,which is mxt informative by n.m.r.,thus holds gcxd for sirohydrodlorin ester (1). oxidativefoI_IrationoflaAcneandlactamgroupsisknown5inthe aIrrIn.Series. lbepublishedspectrashcwthepresenceoflactoneinsawearlierpreparations ofdrchy~

rin ester l,*.

!l!ransesterificaticnofthe~lactoneester (F.D.M? 958)with CD3w-H2s04 gave a product sbwing two parent psaks in the F.D. spsctrunat M? 976 and 979. with CD3cEi-H*so* greatlyinoneofwhichishindered.

the 979 peak.

FurUxx transesterificaticn

Thus,therrpnolactcnehassevenestergroqe,

Ths 1.r. spscbun shobd absorpticmat 1775 an-l (y-la&c&

not

presentin ths SFectnnlof (1).

I

I

8

9

WUJ=.

&.m.r. smzks

I

7

I

8

I

5

I

4

I

I

3

2

spedrun of mznolacta~ ester (2) in CD2C12at 100 MHZ:; solvent.

The u.v.-visible spectraof the mnu>lactcmeester (2) determinedin piperidineand in 5% bobacteriochlorin6 (adjacent rings redwed). In~qrwnw~t, axres~toan cF3C?P i"cH2Cl2 the F.T.

n.m.r.spectraof (21,see figure,and of its CD3 ester &&wed the characteristic well-

~~mes~signals7,oneof~chinthiscaseisadoublet(J,0.9Hz); CF3CD2D,theh@-field~signalwas

rapidly lost, folltiby

seelater. the t.w centralmeso-signals

In

2215

No. 25

whilst that at low fieldwas essentiallyunchangedafter 40 hours.

Thisewhangebehaviour

7, (e.g.3) anfirmad here under our conditionsof matchesthat of know isobacteriochlorins neaswemant; theCRbetween the reducedringsexchangesfastest and the twoCH's adjacentto 7 thereducedrings are slower . 'Mo high-fieldsingletsappear in the n.m.r. spectrumof(2)c=resPndingtowoquaternary C-nethylgroupsand threemethylenesingletsarise fnmCI-12CC2Ms residues,twbeingatla+ field (attachedto "porphyrin" part) and cne at high-field(attachedto "reduced"part). Theforegoingresultsareinfullagreanentwithstructure (2) for the nonolactoneester ' butalternativesinvolvingotherpairsofreducedringsneedtobeexeluded.

wcauseofthe

relationshipofsirohydrochlorin and tbenrnolacMne toccbyrinic aciddemmstrated in the follwingpaper,onlyreduc&ringsA-BamdreducedA-Dneedbe

amsidered~ the stereo-

cLnistry for (1) and (2) is also assignedon the corrinrelationship. The reduoedA-D systemwas excludedby a full n.m.r.deoouplingstudy on (2)which showed thatthedoubletfran~eofthemescrH&ljacentto by couplingto a single proton at e

64.3.

(notbetWeen)the reducedringsarises

Wxk on octaethylisobacteriochlorin (3, cne

diastereoisanar illustrated) shcws this chemicalshift oxrespo~& to C-H at the B-position of areducedring.

Thesedatacanbe acaxmr&ted by allyliccouplingfran C-8 to c-10

cn (2)but cannotbe explainedon the reducedA-Dstructurewhichalso failsanother counts. Finally,the F.T. n.m.r. spectraof the nrmolactoneester (2)ware examiEd8 withpulse [email protected] 0.85 sect05 variousproms

aqxredwith

set; ths relarationratesofths

thoseofuropoqhyrin-II octanethylesteramdoctaethylis&a&er-

iochlorin(3) addedfurtherstrengtbtothe above assignnents. Swrt

for the expectedoriginof the IXKIC-nethylgrwps of (1) amI (2) fran S-adenosyl-

~th~inewasabtainedbytheformaticnofhighlyradioactive

(2)when14C-Pnethioninewas

includedilltbegrow&madirnl (minhmmlspecificincorporation, 55%).

The correqxnding13c-

exparim?ntisinprogress. The follcwingpapershowshowkna~ledgeof the structuresof sirohydrochlorinester (1) and of the nonolactcneester (2) greatlyhelps researd on the biosynthesis of vitmninB12. In addition,amajorproductisolated inour early shown tobeadilactone)

is shown there

extractions ofdesulphoviridin(and later

tohava similarsignificanr~.

Gratefulacknowledgesent is m&a to Dr. D. C. Williamsfor his help with the gruith of the organism,to ProfessorH.-H. Inhoffenfor octaethylporphyrin and to the Nuffield Foundationand S.R.C. for financialsupport. 'Thesrmolactone(2) and the lactcnesin the followingpaper undergosubtlespectmscopi~ andclxana~~cchan~with

acidsandbases.

tautanarisnand/orriq-openingareinprcgress.

Stwliesofpro~ticnandpossible

NO. 25

2216

1.

L. M. Siegel, M. J. Mzphy and H. Kamb, J. Biol. (hem., 1973, 248, 251; M. J. Mxphy

2.

M. J. hbrphy, L. M. Siegel, H. Kamin and D. Rosenthal, J. Biol. Chm.,1973, 248, 2801.

3.

A. R. Battersby, E. McDonald, R. Hollensteh, M. Ihara, F. Satoh and D. C. Wil.&ms,

and L. M. Siegel, ibid, p. 6911.

J. C&m. 4.

Sot., Perkin I, 1977, 166 and refs. therein.

A. R. Battersby, D. G. Bu&ley, G. L. l%zdgscm,R. E. Markwell, andE. !.monald, in "High Pressure Liquid Clzxmatography in Clinical Chemistry", eds. P.F. Nixon, C.H. Gray, C.K. Lh,

and M.S. Still, Acadsmic Press, Imdm,

1976, p.63.

5.

R. Bcmnett, J. R. Cannon, V. M. Clark, A. W. Jahnson, L.F.J. Parker, E. L. Smith

6.

(bllected refs. in ref. 2.

7.

R. Bcmnett, I.A.D. Gale, and G. F. SN,

and A. R. Todd, J. C&m. Soc.,1957, 1158.

J. them. Sot. (c), 1967, 1168;

H.-H. Inhoffen, J. W. Buchler and R. Thnas, l?atrahedrm Letters, 1969, 1141.

8.

I. S. Eenniss, J.K.M. sanders and J. C. Watertcm, J.C.S. Chm. CYc.mm., 1976, 1049.