AbstractReaction of glutarimide with pent‐4‐enylmagnesium bromide, followed by cyclization of intermediate ketoamide, and hydrolysis of the formates10and13led to the mixture of the hydroxylactams11(cis)and14(trans)which could be separatedviatheir benzenecarbamates. Reduction ofcis‐hydroxylactam11with LiAlH4yielded 2‐depentyl‐7‐debutylperhydrohistrionicotoxin (6), whereas reduction oftrans‐isomer14gave the epimeric alcohol9.cis‐Hydroxylactam11was convertedviathiolactam17and the methylthio derivative18to ketimine19which was reduced with NaBH4yielding a mixture of natural4and unnatural7, analogues of perhydrohistrionicotoxin (2). Reduction of4with H2in the presence of Pd/C yielded (±)‐7‐debutylperhydro