Synthesis and conformational analysis of new 17-alkyl derivatives of lupanine and their perchlorate salts

摘要

New 17-alkyl derivatives of lupanine and their perchlorate salts have been synthesised. Substituents at C-17 are introduced by treatment of C(17)= N(16) immonium perchlorate 2 with alkylmagnesium compounds. NMR spectra of the new compounds have been taken to study the chemical shift changes caused by the introduced alkyl substituents, ethyl and butyl. In 17-alkyl derivatives (17-ethyl- ( 3) and 17-butyllupanine (4)) the substituent is equatorially oriented. All the lupanine derivatives analysed have the same structure, i.e. ring C in a boat conformation. The reaction of 17-butyllupanine ( 4) and 17-cyanolupanine ( 5) with methyllithium has led to 17-butyl-2-methyl-2,3-didehydrosparteine ( 6), 17-butyl-2-methylsparteine ( 7) and 17-cyano-2-methyl-2,3-didehydrosparteine (8).