SYNTHESIS OF ORTHO-ACYLBENZYLBORONATES VIA CROSS-COUPLING REACTION OF (DIALKOXYBORYL)METHYLZINC REAGENTS WITH HALOARENES - A STABLE ORTHO-QUINODIMETHANE PRECURSOR

The cross-coupling reaction of IZnCH2B(OCMe2)2 with iodoarenes in the presence of PdCl2(PPh3)2 produces the corresponding benzylic boronates in high yields. Among them, the benzylic boronates having an acyl group at the ortho position readily undergo the 1,5-rearrangement to the carbonyl oxygen producing the o-quinodimethane derivatives under thermal or photochemical conditions. The reaction provides benzo-fused cycloalkanes by trapping with dienophiles.