Unprecedented Rearrangement of beta-Difluoroboryloxy Ethers: A Route to C-2 Alkyl-chromenones

The addition of boron trifluoride etherate (BF3 center dot OEt2) to allenic ketones has led to the isolation of the isolated boron difluoride enolates. The single-crystal structure of boron enolate has been solved. The unprecedented C-1-C-10 migration of (Z)-beta-difluoroboryloxy ether derivatives is observed to deliver rearranged phenol derivatives which are functionalized to C-2 alkyl-chromenones. Interestingly the isolated boron enolates have exhibited significant anticancer properties.