SYNTHESIS AND CD SPECTRAL STUDIES OF SOME FUSED CHOLESTENOPYRIMIDINES

Synthesis of unsubstituted 5 chi-cholesteno(3,2-d)- (5), (2,3-d)- (12) , (3,4-d)- (15) and 5 <-- and 5 beta-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'-derivat ives (5a - 5e), (12a), (15a - 15c), (21a - 21c) and (21'a,21'b) could also be prepared. Attempts to prepare cholest-1-eno(1,2-d) pyrimidine system through 5 chi-cholestan-1-one(28) failed. 5 chi-Cholest-6-eno(7 ,6-d)pyrimidine(33) was prepared by the reaction of cholestan-7-one wi th trisformylaminomethane. Three Cotton effects were observed between 350-200 nm in all these compounds in their CD spectra. They have been assigned to n --> pi and pi --> pi* transitions from long to short wa ve 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.