Synthesis and CD spectral studies of some fused cholestenopyrimidines

Synthesis of unsubstituted 5X'-cholesteno(3,2-d)- (5), (2,3-d)- (12), (3,4-d)(15) and 5.C- and 5 ~-cholest-3-eno(4,3-d)pyrimidines (21) and (21') has been achieved using hydroxymethylene derivatives of relevant cholestanones prepared from cholesterol(1). Their 2'-derivatives (5a - Se), (12a), (15a - 15c), (21a - 21c) and (21'a,21'b) could also be prepared. Attempts to prepare cholest-l-eno(l,2-d)pyrimdine system through 5X-cholestan-l-one(28) failed. 5 $-Cholest-6-eno(7,6-d)pyrimidine(33) was prepared by the reaction of cholestan-7-one with trisformylaminomethane. Three Cotton effects were observed between 350-200 nm in all these compounds intheir CD spectra. They have been assigned to n 3 K* and 7T -tT*transitions from long to short wave lengths. Quadrant rule has been applied for determining the sign of the first band CD, while helicity rule has been applied for the third band CD. Present work describes the synthesis of six series of optically active cholestenopyrimidines (Fig.l), e.g. 5 and its 2'-derivatives (5a-5e), 12 and its