Multicomponent reactions of urea and its derivatives with CH2O and H2S in the synthesis of 1,3,5-thiadiazinane-4-(thi)ones and macroheterocycles.

A convenient, efficient, and practical method for the synthesis of 1,3,5-thiadiazinan-4-(thi)ones via a multicomponent condensation of urea (or thiourea), formaldehyde and hydrogen sulfide in the presence of a four-fold molar excess of n-BuONa is described. It provides the novel acid- (H2SO4) and base- (n-BuONa)-promoted approach for the one-pot synthesis of the amidine containing macroheterocycles from guanidine and diphenylguanidine. X-ray powder diffraction analysis gave insight into the structure of the 4-methyl-sulfonyl-2H-1,3,5-thiadiazine hydriodide. [ABSTRACT FROM AUTHOR]