A Convenient Synthesis of Carbamates, S-alkyl Thiocarbamates and N,N?-Disubstituted Urea Derivatives of Methoxycarbonylsulfenyl Isocyanate

SONIA TORRICO-VALLEJOS; MAURICIO F. ERBEN; EVAMARIE HEY-HAWKINS; CARLOS O. DELLA VÉDOVA

TETRAHEDRON LETTERS

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2011 vol. 52 p. 5352 - 5354

0040-4039

A convenient, one-pot procedure for the synthesis of carbamates, N,N?-unsymmetrically disubstituted ureas and S-alkyl thiocarbamates derived from CH3OC(O)SNCO is provided. Reactions are operationally simple, offers high yields, short reaction time, and high selectivity toward nitrogen, oxygen and sulfur nucleophiles. The absence of solvents coupled with the high yields and short reaction times make these procedures very attractive for synthesis. The chemistry of isocyanates has been thoroughly covered in review articles.1,2 The reactions of isocyanates with active hydrogen compounds involve attack by a nucleophilic center upon the electrophilic carbon of the isocyanate.1 The reaction of isocyanates with compounds containing nitrogen-hydrogen bonds is governed primarily for the basicity or nucleophilicity of the N-H bond and yields urea derivative compounds.3 Reactions of isocyanates with compounds containing an O?H bond represent one of the most important areas of isocyanates chemistry.4-6 Thus organic carbamates are a class of compounds that received special attention because of their multiple applications as protective groups for amine function in amino acids in peptide chemistry.7 In addition, they play an important role in the synthesis of pharmaceuticals, agricultural chemicals and in the chemical industry.8,9 It is also known that the thiol group reacts in the same way as its oxygen analog, except that it is less reactive.10 Thus condensation of a thiol with an isocyanate affords the corresponding thiocarbamate.11 S-alkyl thiocarbamates have received considerable attention in the literature mainly because they are potent herbicides 12,13 and due to their wide biological effects14 with anesthetic,15 bactericidal,11 pesticide and antiviral activities.16-23 In the present work we investigate the reactivity of the recently synthesized methoxycarbonylsulfenyl isocyanate, CH3OC(O)SNCO, toward addition reactions with alcohols, amines and thiols (see Scheme 1). The synthesis of novel carbamate, urea and S-alkyl thiocarbamate derivatives is achieved in a simple way without the use of solvents.