65 大環状ピロリチジンアルカロイドの合成研究

概要

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Synthetic studies on the macrocyclic pyrrolizidine alkaloids are described. I. Racemic retronecine (1) and otonecine (2) were synthesized from a common and key intermediate 5. II. Dicrotaline (23), an 11-membered pyrrolizidine alkaloid was synthesized by virtue of a newly developed method using the stannoxane 19. III. Total synthesis of optically active integerrimine (3), a representative of the 12-membered dilactonic pyrrolizidine alkaloids was achieved as follows: (1) Optically active retronecine (1) was synthesized enantioselectively from (+)-malic acid (12). (2) The optically active integerrinecic acid derivative 32 was synthesized enantioselectively from an unsaturated acid 25. (3) The necic acid derivative 32 was converted to the cyclic anhydride 33, which was reacted with the stannoxane 19 to give the monoester 34 regioselectively. Lactonization of 34 by the Yamaguchi's method provided integerrimine MTM ether (35), which was converted to (-)-integerrimine (3).
天然有機化合物討論会の論文
1986-09-09