Palladium-catalyzed double cross-coupling reaction of 1,2-bis(pinacolatoboryl)alkenes and -arenes with 2,2′-dibromobiaryls: annulative approach to functionalized polycyclic aromatic hydrocarbons

摘要

This study demonstrates that the double cross-coupling reaction of 1, 2-bis(pinacolatoboryl)alkenes and -arenes with 2, 2′-dibromobiaryls proceeds smoothly with the aid of a catalytic amount of Pd(PPh3)4 in the presence of excess base to give a variety of polycyclic aromatic hydrocarbons, such as phenanthrenes, [5]helicene, dithienobenzenes, triphenylenes, dibenzo[g, p]chrysenes, and triphenyleno[1, 2-b:4, 3-b′]dithiophenes in good to high yields. It is noteworthy that the annulations using 2, 2′-dibromooctafluorobiphenyl as an electrophile furnish the otherwise difficult to synthesize octafluorophenanthrenes and semi-fluorinated dibenzo[g, p]chrysenes in high yields.