Highly Efficient Synthesis of 1,1-Difluoro-2-substituted-1,3-dienes and Dienynes from gem-Difluorohomoallenyl Bromide via Palladium-Catalyzed Cross-Coupling Reactions

[reaction: see text] A stable gem-difluoroallenylindium 1 is readily transformed to a potentially bifunctional electrophile 2, which can then undergo a transition-metal-promoted isomerization-cross-coupling cascade to yield diene 3 and dienyne 4 in very high yields.