Gelsemine: Iii. Reduction With Lithium Aluminum Hydride

Abstract

The infrarecl alrsorptinr~ spectrum of gelsemine inclicatcs the prcscncc o l a carbon)-l group. Recluction cf the alkaloid with lithiurn alurl~inuun hyclr-itlc converts the carbonyl no1 ra a r;ccontlar). alcohol, but to a 1uet11)-lene group, thus indicating hat thc carOo~l!-l is present irr a lactan~ic grouping. Ttlc I-ctl~~cetl base shoxvs thc properrics oi a s~ibstituted aniline. Since geiscnlinc has been s h o n r ~ to yielcl 3-erhylinclolc un clel~ytlrogenation with seleni~rnl ant1 since the N-atom involvctl in the l a c ~a r l ~i c group capnot be the strongly basic nitrogen, gclsen~ine ni~rst contain ;In nxinclole grouping. Furthern~ore, 3 -~n d n o s ~r h s t i t ~e c i orindoles are cor~vertctl by l i i h i ~r o ~ ~I U ~I I ~~L I I I I hyclride to 3 -s ~r b s t i ~u ~c d incloles, wl~ereas gelscrnine ~~n c l c r the same co~lclitions gives rise to a dihyclrointlole.'l'herefore, the alkaloitl m u s t contain a 3, 3-clisubstitutetl oxindolc grouping.