Parallel solid-phase synthesis of novel 3,7-diazabicyclo[3.3.1]nonane derivatives starting from natural alkaloid cytisine

A parallel solid-phase synthesis of combinatorial library of 436 amides of 4-(3,7-diorganyl-3,7-diazabicyclo[3.3.1]nonan-2-yl)butanoic acid has been accomplished starting from natural alcaloid (−)-cytisine. A five-step liquid-phase synthesis resulted in the conversion of cytisine to 7-benzyl-3-[(9 H -fluoren-9-yl)methyl]-substituted acids, which were further diversified with the use of solid-phase technology on the acid-susceptible amine resins. The combinatorial library obtained is intended for a discovery of new physiologically active compounds.