Two-atom azirine ring expansion reaction of methyl 2-diazo-3-(4-methoxyphenyl)-3-oxopropanoate via a dirhodium tetraacetate-catalyzed Wolff rearrangement

Abstract

Rh₂(OAc)₄-catalyzed Wolff rearrangement of methyl 2-diazo-3(4-methoxyphenyl)-3-oxopropanoate gave methoxycarbonyl(4-methoxyphenyl)ketene that was added to 2Н-azirines, resulting in opening of the three-membered ring at the N–C(2) bond and leading to the formation of 3,4-dihydro-2Н-pyrrol-2-one derivatives. Depending on the structure of the obtained products, they isomerized to the more stable 1Н-pyrrol-2(3H)-one derivatives or added a water molecule at the C=N bond.