NEW MATERIAL: 5,6-Dihydrocyclopentathiophenyl-imidazole deriv. of formula I (wherein X is formula II, formula III, etc.; R1 is H and SH; L is CN, COOH, COOR8, COSR8, etc.; R2 and R3 are each H, an alkyl, an alkenyl, etc., R4 and R5 are each H and an alkyl; R6 is H, CN, a halogen, an alkyl, NO2, etc.; R7 is H, a halogen and an alkyl; R8 is an alkyl, a cycloalkyl, benzyl, etc.), their stereoisomers and their salts.

EXAMPLE: 1-(5,6-Dihydro-5,5-dimethyl-4H-cyclopenta[b]thiopshen-4-yl)-5-imidazole carboxylic acid methyl ester.

USE: Selective herbicides.

PROCESS: N-cyanoformamidine of formula IV is alkylated with a haloacetate in the presence of a base and the obtd. intermediate product of formula IV is cyclized to obtain a compd. of formula VII and then, diazotization and removal of nitrogen are performed to obtain the compd. of the formula I wherein R1 is H.