ABSTRACT: By aryl-sulfonyl-ation of cytisine in the presence of tri-ethyl-amine, three new compounds have been obtained in good yields: (7R,9R)-N-[(4-ethyl-phen-yl)sulfon-yl]cytisine, C19H22N2O3S (I) {systematic name: (1R,5R)-3-[(4-ethyl-phen-yl)sulfon-yl]-1,2,3,4,5,6-hexa-hydro-8H-1,5-methano-pyrido[1,2-a][1,5]diazo-cin-8-one}, (7R,9R)-N-[(4-chloro-phen-yl)sulfon-yl]cytisine, C17H17ClN2O3S (II) {systematic name: (1R,5R)-3-[(4-chloro-phen-yl)sulfon-yl]-1,2,3,4,5,6-hexa-hydro-8H-1,5-methano-pyrido[1,2-a][1,5]diazo-cin-8-one} and (7R,9R)-N-[(3-nitro-phen-yl)sulfon-yl]cytisine, C1
