The palladium-catalyzed reaction of pinacolone with tert-butyldimethyl(3-(2
-bromophenyl)allyloxy)-silane results in direct formation of 1-vinyl-3-tert
-butyl-1H-isochromene. This is the result of a ketone arylation followed by
an intramolecular cyclization of the enolate with the allylic system. The
use of a lithium diamide base appears to be essential for success. The tert
-butyldimethylsilyl protecting group is also an essential choice as it furn
ishes the appropriate reactivity to promote allylic substitution after the
aryl coupling process. The use of more effective leaving groups, such as ac
etate, results in reaction of the allylic group, and no aryl coupling is ob
served. Through the appropriate selection of phosphine ligand and solvent,
either the cyclized isochromene product or the noncyclized intermediate may
be formed selectively. A short combinatorial study of the scope and limita
tions of the reaction, involving 24 ketones, is described.