Palladium tert-butyl substituent

Larock and Dai developed the synthesis of isoquinolines via palladium-catalyzed coupling of organic halides with 2-(l-allqmyl)benzaldimines. Starting from N-tert-butyl-2-(l-alkynyl)benzaldimines and aiyl, allylic, benzylic, alkynyl halides, as well as a vinylic halide, the corresponding 3,4-disubstituted isoquinolines with aryl, allylic, benzylic, 1-alkynyl, and vinylic substituents, respectively, in the 4-position were produced in good yields. The reaetion appears to require an aiyl group on the end of the acetylene furthest from the imine functionality. 

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