CHEMICAL MODIFICATION OF PLANT ALKALOIDS. 8. STEREOCONTROLLED T-REACTIONS OF (1R,5S,12S)-TETRAHYDROCYTISINE DERIVATIVES

摘要

New heterocyclic quinolizidine systems were prepared from (1R,5S,12S)-tetrahydrocytisine. The synthetic scheme included arylation of tetrahydrocytisine by 2-fluoro-5-nitrobenzaldehyde and condensation of the resulting aldehyde with 1,3-ditnethylbarbituric acid. The Knoevenagel intermediate obtained from the condensation was cyclized by a T-reaction to give two spirocyclic products as a derivative with the lupanine skeleton and its regioisomer with the 11,15-diazapentacyclo[11.7.1.0(2,11).0(5,10).0(15,20)] heneicosane skeleton. The cyclization occurred highly stereoselectively. The structures of the products were proven using NMR and X-ray crystal structure analyses.