Methyltropic tautomerism of the N–C–O and N–C–S groups: synthesis of methyl mono- and di-thiocyanurates

Abstract

A number of well defined trimethyl mono- and di-thiocyanurates have been synthesised following a procedure which consists of two reactions, (i) nucleophilic substitution of an SMe group, bound to a substituted s-triazine ring, with an OMe group; and (ii) the thermal isomerisation of the product of reaction (i). Two reaction sequences are described whose starting compounds are respectively the unsymmetric S,N,N-(1) and S,S,N-trimethyl trithiocyanurates (9). The corresponding dimethyl esters were obtained upon hydroysis of the products of reaction (i).

Four trimethyl and two dimethyl dithiocyanurates; and four trimethyl and two dimethyl monothiocyanurates have been obtained and characterised; ten of them are reported for the first time.

The rules of methyl migration in the thermal isomerisation, established in previous works, are confirmed and extended.