An unexpected formation of cyclic α-alkoxy isothioureas has been achieved. As is known, the heterocyclic imines 2,5-dihydro-1,3-thiazoles are convertible to bisamides with the aid of a carboxylic acid and an isocyanide (Ugi reaction). Herein, it is shown that 2,5-dihydro-1,3-thiazole S-monoxides-the respective α-sulfinyl imines-are characterized by an altered reaction behavior. In a hitherto unknown multicomponent reaction the α-sulfinyl imines react with an isocyanide under acidic conditions in an alcoholic solution to the respective α-alkoxy isothioureas in good yields. In addition to the investigations on this unexpected synthesis the regioselectivity of the acylation of the synthesized compounds is described. A rearrangement, which is accelerated by EDC and HOBt, between both possible regioisomers was found.

A New Multicomponent Reaction: Unexpected Formation of Derivatizable Cyclic -Alkoxy Isothioureas. -The reaction of thiazoline S-monoxides with isonitriles gives cyclic -alkoxy isothioureas. Acylation of the products results in the formation of the kinetic product (X) acylated at the exocyclic nitrogen. A rearrangement to the thermodynamic product (IX) which is acylated at the endocyclic nitrogen occurs, but is very slow in case of product (Xc). -(BROCKMEYER, F.; MOROSOW, V.; MARTENS*, J.; Org. Biomol. Chem. 13 (2015) 11, 3341-3346, http://dx.