PALLADIUM-CATALYZED TANDEM CYCLIZATION - ANION CAPTURE PROCESSES .2. CYCLIZATION ONTO ALKYNES OR ALLENES WITH HYDRIDE CAPTURE

A wide range of palladium catalysed regio- and stereo-specific 5-, 6- and 7-exo-dig mono-, bis- and tris-cyclisation processes of aryl and v inyl halides and allylic acetates are described. The mono- and bis-cyc lisation processes terminate in hydride capture from piperidine-formic acid or sodium formate. Addition of TI2CO3 results in alkyne-allene i somerisation and leads, after cyclisation, to 1,3-dienes which give Di els-Alder adducts in good yield. Copyright (C) 1996 Elsevier Science L td