Selenenylation–acylation of ketones with 2-chloroselenobenzoyl chloride. A novel route to benzo[b]selenophenes

It has been found that enolizable ketones and 1,3-diones react in neutral or basic medium with biselectro-philes such as 2-chloroselenobenzoyl chloride. The reaction takes place on the active α-methylene group. Selenenylation and subsequent acylation of the α-carbon atom take place and, depending on the ketone used, 3-hydroxybenzo[b]selenophenes or benzo[b]selenophen-3(2H)-ones are produced in moderate to high yields.