Development of direct allylation of amine catalyzed by Lewis acid

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We have investigated the synthesis chiral non-racemic 1-alkenyl substituted tetrahydroisoquinoline 2 by the Bi(OTf)_3 catalyzed intramolecular cyclization of chiral non-racemic amino alcohol 1. The investigation of substituent effect on the benzene ring of 1 for the cyclization is described. Although 6-methoxy-1-propenyltetrahydroisoquinoline was obtained as a racemate, the corresponding 6-pivaloyloxytetrahydroisoquinoline was obtained stereospecifically in a 93 : 7 ratio. Based on the results, the synthesis of enantiopure 7-methoxy-6-pivaloyloxy-1-propenyltetrahydro isoquinoline has been accomplished, which converted to natural alkaloids, (+)-trolline and(-)-crispine A.