Conversion of Amides to<i>S</i>-Alkyl and<i>S</i>-Aryl Thioesters via Nitrosoamides and Nitroamides
作者:Ramon Berenguer、Jordi Garcia、Jaume Vilarrasa
DOI:10.1055/s-1989-27234
日期:——
Thiolates react at room temperature with nitrosoamides and, even more rapidly, with nitroamides to afford good yields of S-alkyl and S-aryl thioesters; by-products arising from N-to-S transnitrosations and transnitrations are practically not observed.
Rearrangement of imidoyl nitrates to N-nitro amides: an intramolecular [1,3] O-to-N migration of a nitro group
作者:Emilia Carvalho、Jim Iley、Eduarda Rosa
DOI:10.1039/c39880001249
日期:——
Imidoyl nitrates, formed by the reaction of imidoyl chlorides with AgNO3, rearrange via a unimolecular, intramolecular mechanism probably involving homolytic fission of the O–N bond to yield N-nitro amides; migration of the nitro group in N-arylimidoyl nitrates to the ortho- and para-positions of the N-aryl ring does not involve a special ortho-directing effect.
The reactivity of several nitrating mixtures with amides has been compared. Ammonium nitrate/trifluoroacetic anhydride, morpholinium nitrate/trifluoroacetic anhydride, and morpholinium nitrate/heptafluorobutyric anhydride are the reagents of choice since, in CH2Cl2 at 0-degrees-C, they give N-alkyl-N-nitrocarboxamides and N-nitrolactams in excellent yields. Mechanistic details of these nitrations have been elucidated. Trifluoroacetyl nitrate, which arises from the reaction R2NH2+NO3- + 2(CF3CO)2O --> CF3COONO2 + CF3CONR2 + 2CF3COOH, appears to cause the direct N-nitration of carboxamides.