Prins reaction of 2-oxabicyclo[3.3.0]oct-6-en-3-one and related derivatives

Abstract Reaction of formaldehyde with the title olefinic lactone in acetic acid affords diacetate of 1,3-diol ( 2a ) as the main product in 50 – 60% yield via regioselective trans-addition. Less favourable results were obtained with related bicyclic derivatives.