L. Fisera et al., 1,3-DIPOLAR CYCLOADDITION OF NITRONES AND NITRILE OXIDES TO 5,5-DIMETHYL-3-METHYLENEPYRROLIDINE-2-THIONE, Heterocycles, 40(1), 1995, pp. 271-278
A simple synthesis of title compound (3) and a number of different cyc
loadditions are described. C-Aroyl- and C,N-diphenyl-nitrones react re
gio- and stereoselectively to the C=C exocyclic double bond of 3, to g
ive only spirocycloadduct (10). On the other hand, C-phenyl-N-methylni
trone gives a mixture of diastereomeric spirocycloadducts (10) and (11
). Nitrile oxides undergo 1,3-dipolar cycloaddition both to the exocyc
lic C=C and C=S double bonds with subsequent cycloreversion and format
ion of spiro-lactams (6). The appropriate spiro-thiolactams (8) were s
ynthetized by treatment of 6 with Lawesson's reagent.