BENZOPYRAN DERIVATIVE, ITS PRODUCTION AND HERBICIDE CONTAINING THE SAME AS ACTIVE INGREDIENT

摘要

PURPOSE:To obtain a new compound, extremely safe for useful crops such as rice plant, soybean and cotton, excellent in selectivity for the crops and useful as a herbicide, etc. CONSTITUTION:The compound is expressed by formula I [R1 is a lower alkyl; R2 is a lower alkyl, lower alkoxy, halogen etc.; R3 is a lower alkyl, lower alkoxy, halogen, phenoxy, etc.; R4 is H or a lower alkyl; (m) and (n) are respectively 0-4], e.g. (2R, 3S, 3aS, 9bR)-2-ethyl-3-(2-fluorobenzyloxy)-3, 3a, 5, 9btetrahydro-2H-furo{9146/28}3, 2c][2]benzopyran. Furthermore, the compound expressed by formula I is obtained by subjecting a substituted tetrahydrofuran derivative expressed by formula II (R5 is a lower alkyl or lower acyl) to the intramolecular cyclizing reaction in an inert solvent.