Cycloaddition in synthesis of sulfonamide derivatives. II. Synthesis of N-arylsulfonylethoxalamides by cycloaddition of arylsulfonyl isocyanates to ethyl oxamates.
作者:Hiroto TAMURA、Tsuneo IWAKAWA、Yoshio HAYASE
DOI:10.1248/cpb.38.1069
日期:——
A new class of sulfonamides, N2-arylsulfonyl-N1, N1-disubstituted ethoxalamidines, was synthesized by reaction of arylsulfonyl isocyanates with N, N-disubstituted ethyl oxamates. It was suggested that the reacion might proceed through [2+2] cycloaddition of the isocyanates to an amide carbonyl moiety with high selectivity.
N-dimethylamino)(3-methoxycarbonyl-2-methylphenyl)carbene]chromium(0) [(S)-6] and (R)-pentacarbonyl[(N,N-dimethylamino)(5-methoxycarbonyl-2-methylphenyl)carbene]chromium(0) [(R)-7], were prepared in enantiomericallypure form by the crystallization of diastereoisomeric esters with (S)-1-(1-naphthyl)ethanol. In the case of (S)-6 the racemization barrier ΔG⧧rac = 121 ± 0.5 kJ·mol−1 was established. The substitution