| 摘要 |
A process for the preparation of 4-methylenepiperidines of general formula (VII) which comprises reacting an isonipecotate of general formula (I) (wherein R1 is methyl or ethyl) with an acylating agent of general formula (II): R2X or the general formula (II'): (R2)2O (wherein R2 is benzoyl or acetyl; and X is chlorine or bromine) in the presence or absence of a base to form an ester of general formula (III) (wherein R1 and R2 are each as defined above), reducing the ester with sodium borohydride or lithium borohydride in an organic solvent containing methanol, reacting the alcohol thus obtained with a halogenating agent without any solvent or in an organic solvent in the presence or absence of a base to obtain a halide, reacting this halide with a dehydrohalogenating agent in an organic solvent to obtain a methylene compound of general formula (VI) (wherein R2 is as defined above), and hydrolyzing the methylene compound with a strong alkali in water or an organic solvent containing water.
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