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019 TEE STRUCTURE OF DIOSCORIEET.L.V. lbrioht

University hemical aboratory,ensfield oad, ambridge

AFl!ER nvestigationshas either truotum

(Reoeived 9 January 939)by Pinder -7had shown hat the alkaloid iosoorineI or II, &ohi et a1.8presented vidence n favour

, o-co\CLco-o \NC HC CH-CH*- CH, I II we ct%

=q-i;crT;aI I NMr CH, MeMe I ICH~-cH - CH, CHdH-CH*

I IIof I. It wa& subsequentlyhown y Pinder that this cannot be oorrect,ardthat he ooneot structure ust be II.

1 I.C.I. ellow.2 A.R. Pinder, ature and, 6,!, 090 (1931).3 A.R. Pinder, . Chem. 00,2236(1932).4 A.R. Plnder, . Chew Soa, 1823 (1953).5 A.R. Pinder, . Chew QOO, 577 (1936).6 A.R. Pinder, hem, Ind, 1240 (1937).7 A.R. Pinder, etrshedron, 301 (1937).0 G. Gohi, D.E. yerof Pure and Applied

' J.B. Jones nd A.R.

and D.E. White, VIth nternationalongressChemistry,aris, uly 1957.Pinder,Chew k hi, 1000 (1938).

5

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6 On the rtruoture f Moeoorine!l'hlrtruoture s now supported y &hl.lo His earlier videnoe

la favour f struoture was as fallows~(1) That he ketone erived y degradationf the laotone ing

(i.e., -1III or IV) had a oarbonyl and In the infra-red t 1730'01111723 WI? (CS2) lo and that this was In better agreement ith a omlo-pentanone than with a osolohexanone structure. inder as already ointsdout 9 that thi s I s not so; In faot, aooepted anges 11 are 1720-1706 m"for oyolohexanonesnd 1749-1745 III-'or oyolopentanones.t is relevant

oq- CH - CHII- I 1I NM CH.I- CH,III

to oonsider ore olossly elated ompoundsrhe oarbonjrlrsquen& in

i T-i0I ihk aCH,cw,- CH - CH,

IQ

tropinone j-oxotropane)b at 1722 oml (Nujol)and in 6-hydroxytropi-none l2 at 1705 ox ' (Nujol), 715 cm" (CC14). his clearly supports theoyclohexanone truoture (Iv) for the ketone, aud is oonfirmed y theposition of the carbonyl aud in 6-oxotropane III),' hioh S at 1750-1cm # as expected or a oyclopentanone.

10 D.E. yer, . Gohi, P. Reynolds-War&offnd D.M. hite, . Ame r ,11 them. SOO, a~, 6146 (1958).L. J. Bellamy, The I.R. Spectra of Complex oleaules, ethuen,

London (1958).l2 Samples were generously rovided y Professor . Stoll and

Dr. N. Clauson-Kaas.

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On the structure of Dioscorine 7(2) That Hofmanu degradation of the oxotropane (now known to be

IV) methiodide oocurred very readily (aqueous sodium bicarbonate at 30).Thiele not referred to in &hive more recent communication, 10 althoughit becomes even more curious since 6-oxotropane, which, of the two com-pounds, should eliminate more readily, ie unaffected by the same reagent.

Thue, although the weight of the evidence 13 definitely eupportePinder@a structure (II) for Dioscorine, there remains an anomeloue pieceof evidence against it.

13 The degraaation product, P-oxotropane, haa been eyntheaiaed[M.R. Bell and S. Archer, J . Amer. Chem. Soo, $2, 6147 (1958a.