T. Shimo et al., SYNTHESIS OF 9-OXA-5-AZATRICYCLO[4.3.0.0(3,7)]NONAN-4-ONES FROM OXY-2-OXABICYCLO[3.2.0]HEPTANE-EXO-6-CARBONITRILES BY THEIR RING TRANSFORMATION, Bulletin of the Chemical Society of Japan, 67(10), 1994, pp. 2891-2893
The hydrolysis of [2+2]cycloadducts 4 or their hydrates 5, which were
obtained from the regioselective photoreactions of 4-hydroxy-2,5-dimet
hyl-3(2H)-furanone (1) with cyanoethylenes, afforded the tittle gamma-
lactams 7 via an interesting ring transformation.