New Piperidinic Synthons via Ring Contraction. Formal Synthesis of (+/-)-Perhydrohistrionicotoxin

Article abstract of DOI:10.1246/bcsj.59.2353

The 2,2-bifunctionalized piperidines 6 and 10 were obtained via ring contraction of the seven-membered heterocyclic enamino aldehyde 5 in nearly quantitative yield.The synthesis of 1-benzyl-1-azaspiro<5.5>undec-7-en-9-one 9 (a formal precursor or perhydrohistrionicotoxin 1b) in 3 steps from the piperidinedialdehyde monoacetal 6, is reported.