Synthesis of Anatoxin-a

Article abstract of DOI:10.1021/jo00363a015

A short efficient synthesis of (+/-)-anatoxin-a, the alkaloidal toxin from Anabaena flos-aquae, is described.Bromination of 9-methyl-9-azabicyclo<3.3.1>nonan-1-ol (3b) provides the key intermediate 9-methyl-9-azabicyclo<4.2.1>nonan-2-one (6).Reaction of 6 with diethyl (1-cyanoethyl)phosphonate gives 2-(1-cyano-1-ethylidene)-9-methyl-9-azabicyclo<4.2.1>nonane (8).Oxygenation of 8, followed by reduction and hydrolysis, gives N-methylanatoxin-a (1b) which has been earlier converted into anatoxin-a.