Kiyoharu Hayano

Conformationally selective transannular cyclizations of humulene 9,10-epoxide. Synthesis of the two skeletally different cyclohumulanoids: dl-bicyclohumulenone and dl-africanol

Two cyclohumulanoids, dl-bicyclohumulenone (4) and dl-africanol (7 were synthesized through newly developed conformationally selective transannular cyclization of humulene 9,10-epoxide (2). The epoxide 2 was converted to a bicyclohumulenediol diacetate 3a in 70% yield by treatment with BF3·OEt2-Ac2O, while treatment of 2 with trimethylsilyl trifluoromethansulfonate gave an africen-10-ol (5a and 5b) in 80% yield. The two intermediates 3a and 5a furnished the natural products 4 and 7 in 30 and 8 % yield from 2 respectively.

Clitidine, a new toxic pyridine nucleoside from clitocybe acromelalga

Abstract From a poisonous mushroom, Clitocybe acromelalga , a new nucleoside clitidine ( 1 ) was isolated as a toxic principle. The structure was deduced to be 1 from spectral data and chemical degradation studies. Synthesis of 1 through condensation of methyl 4-aminonicotinate with 3, 5-di- O -benzoyl-D-ribofuranosyl chloride confirmed the structure, including absolute configuration.