NEW MATERIAL:1,2-Thiazacycloalkene derivative of formula I (n is 3W6; Ts is tosyl).

EXAMPLE: 2-Tosyl-3H,6H,7H,8H-1,2-thiazocine.

USE: It is used as a fungicide for agricultural and horticultural purposes, or as a synthetic intermediate of a variety of organic compounds. It has good fungistatic action against a variety of Phytomycetes and fungi causing late blight in tomatos and potatos, downy mildew in cucumber and vines.

PREPARATION: A compound of formula II is allowed to react with chloramine T (tosylchloramide saodium) in a solvent such as methanol to give a ylide derivative of formula III, when needed, followed by heating to give the compound of formula I . The molar ratio of chloramine T to the starting material is suitably about 1,1 equivalent, in general.