Reactions of CH2N2 with 5-exo,6-exo-isopropylidenedioxy-7-oxabicyclo[2.2.1]heptan-2-one and 3-substituted derivatives have been studied. The regioselectivity of the one-carbon ring enlargement process depends on the nature of the substituent at C(3) and on its relative configuration.
Philipp Georg Werner Seeberger