N-bromobutanimide → ethyl 4-ethoxy-1-vinyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylate

Participants

Reaction Steps

A suspension of ethyl 1-ethyl-4-ethoxy-1H-pyrazolo[3,4-b]pyridine-5-carboxylate (which may be prepared as described in U.S. Pat. No. 3,755,340, for example, Example 1c) (14.24 g.) and N-bromosuccinimide (21.2 g.) in carbon tetrachloride (109 ml.) was stirred and heated under reflux while being irradiated with a sun lamp (Westinghouse 250 watt). After 1.5 hours the mixture was cooled (ice-bath) and filtered. The filtrate was washed with aqueous sodium bicarbonate and water, dried (MgSO4) and evaporated to give ethyl 4-ethoxy-1-vinyl-1H-pyrazolo[3,4-b]pyridine-5-carboxylate as a yellow oil.

Provenance & Evidence