Different Reactivity of Hydroxylamine with Carbamoyl Azides and Carbamoyl Cyanides: Synthesis of Hydroxyureas and Carbamoyl Amidoximes

Abstract

The carbamoylating agents carbamoyl azides and carbamoyl cyanides (aka cyanoformamides) react with hydroxylamine in different ways, leading in the first case to N-hydroxyureas and, in the case of carbamoyl cyanides, to carbamoyl amidoxime derivatives. The synthetic procedure developed for the latter type of compound, which represents an interesting precursor for heterocyclic structures, allowed the highly efficient preparation of a wide selection of examples. The Z configuration of the double bond in the amidoxime moiety was proposed on the basis of comparison between experimental and calculated 13C and 15N NMR chemical shift values for the isopropyl and benzyl derivatives.

An efficient synthesis of imidodicarbonic diamides from 1,3-thiazetidin-2-ones with NH2OH·HCl via ring-opening reaction

“…3 (details see Supporting information). On the basis of the above experimental results, a possible mechanism is shown in Scheme 6 [17,18]. Intermediates 1 firstly reacted with NH 2 OH to form A and H 2 S. Then, an intramolecular ring-opening reaction took place to afford transition state B in the presence of H + , followed by addition of proton to afford the imidodicarbonic diamides 2 (R 2 = Ar).…”

Acyclic and Cyclic Ureas (Update 2013)

“…Under optimized reaction conditions, a variety of carbamoyl azides including those derived from amino acids can be used in this reaction and give the products in excellent yields. [347] N-Hydroxyureas obtained from a-amino esters cyclize in basic media to give the corresponding 3-hydroxyimidazolidine-2,4-diones (Scheme 127). When using O-benzylhydroxylamine for the reaction with an isocyanate, a (benzyloxy)urea is obtained, which can be converted into the free N-hydroxyurea by hydrogenation.…”

“…Scheme 127 Synthesis of N-Hydroxyureas from Carbamoyl Azides with Further Reaction To Afford 3-Hydroxyimidazolidine-2,4-diones[347] …”

Solvent‐Free Synthesis of Cyanoformamides from Carbamoyl Imidazoles

“…The increasing number of recent synthetic applications of cyanoformamides has highlighted the need for more efficient synthetic routes to access these compounds. For example, cyanoformamides have been used for intramolecular alkene cyanoamidation, enantioselective synthesis of disubstituted oxindoles, the synthesis of N ‐hydroxy ureas, lactams, tetrazoles and various other heterocyclic compounds . Furthermore, N ‐methoxy‐ N ‐methylcyanoformamide has recently been used as a carbonyl dication synthon in the synthesis of unsymmetrical ketones and as a means to install Weinreb amide functionality .…”