Process for reparing 2,2,3,3-tetrafluoro-1,4-benzodioxanes, new o-(2-bromo-1,1,2,2,-tetrafluoroethoxy)-phenols and new2-bromo-1,1,2,2-tetrafuoroethoxy-phenylethers

摘要

Preparation of 2,2,3,3-tetrafluoro-1,4-benzodioxan derivatives of formula (I) comprises: (a) reacting a pyrocatechol mono-ether of formula (IV) with 1,2-dibromo-1,1,2,2-tetrafluoroethane in the presence of an acid binder; (b) subjecting the obtained diether of formula (III) to ether cleavage; and (c) cyclo-condensing the obtained mono-2-bromo-1,1,2,2-tetrafluoroethyl ether of formula (II) in presence of an acid binder to give (I). R1-R4 = H, halo or 1-6C alkyl; or two adjacent R1-R4 = (CH2)3, (CH2)4, (CH2)5, or CH=CH-CH=CH (optionally substituted by halo or 1-6C alkyl); one or two of R1-R4 may also = NO2, CN, COR6 or C(OR7)2R6; R6 = H or 1-6C alkyl; R7 = 1-6C alkyl; or R7+R7 = CH2CH2, CH2CHMe, CH2CHEt or CHMeCHMe; and R5 = 1-6C alkyl or benzyl. Also claimed are: (i) (II) and (III) (excluding 1-(2-bromo-1,1,2,2-tetrafluoroethoxy)-2-methoxy-4-nitro-benzene); and (ii) steps (a), (b) and (c) as separate processes.