43 トロパンアルカロイドの新規一般合成法の確立

抄録

Cyclocoupling reaction of α,α,α',α'-tetrabromoacetone and N-carbomethoxypyrrole with the aid of diiron nonacarbonyl gives N-carbomethoxy-2,4-dibromo-8-azabicyclo[3.2.1]oct-6-en-3-ones (stereoisomers). Treatment of the adducts with zinc-copper couple in methanol affords the dehalogenation product, N-carbo-methoxy-8-azabicyclo[3.2.1]oct-6-en-3-one, which upon diisobutyl-aluminum hydride reduction is converted selectively to N-methyl-8-azabicyclo[3.2.1]oct-6-en-3α-ol (6-dehydrotropine). Since the unsaturated alcohol can be transformed to all naturally occurring tropane derivatives, the present procedure marks the realization of a new, general synthesis of the alkaloid family.