Aa. Tishkov et al., Chemistry of beta-functionalized alpha-nitroso ethylenes. Methyl beta-nitroso acrylate as heterodienophile in [4+2]cycloaddition to cyclic dienes, ORG LETT, 2(9), 2000, pp. 1323-1324
beta-Functionalized nitroso alkene 2, obtained from methyl beta-nitropropio
nate 1 and N,O-bis(trimethylsilyl)acetamide, can function as a good heterod
ienophile in Diels-Alder reactions, Therefore, 2 was trapped by cyclic dien
es to give adducts 4 with the corresponding stereoselectivity, Cycloadduct
4a undergoes retro[4 + 2]-cycloaddition at 33 degrees C in solution; thus 4
a can be used to generate nitroso alkene 2 in neutral medium. Cyclopentadie
ne reacts with adduct 4a according to an endo-[4 + 5]-cycloaddition scheme
to give cycloadduct 5 in low yield.