Linear poly:cyclic cpds. prodn. from boronic acid and halogen cpds. - by cross-coupling in aq. solvent in presence of catalyst and water-soluble borate, esp. prodn. of liquid crystal cpds. with fluoro-phenoxy gp.

摘要

Prodn. of linear polycyclic cpds. of formula (I) by cross-coupling of boronic acids of formula (II) with Br or I cpds. of formula (III) is carried out in a solvent-water mixt. in the presence of a transition metal catalyst and a water-soluble borate (IV). In the formulae, R1-2 and X1-4 = 1-15 C alkyl, alkoxy or alkylene, opt. with halogen substit(s)., in which one or more CH2 gps. may be replaced by -O-, -S-, 1,3-cyclobutylene, 1,3-cyclobuta-1,2-dienylene, -CO-, -CO-O-, -O-CO- or -O-CO-O, without directly linked O atoms; and R2 may also = -CN, -NCS, Cl, F, -CF3, -OCF3, -OCF2H or -OC2F5; A1-2 = (a) trans-1,4- cyclohexylene, in which one or more non-adjacent CH2 gps. may be replaced by -O- and/or -S-; (b) 1,4-phenylene, in which one or two CH gps. may be replaced by N; or (c) 1,4- cyclohexenylene, 1,4-bicyclo(2,2,2)- octoylene, piperidin-1,4-diyl, naphth-2,6-diyl, decahydronaphth- 2,6-diyl and 1,2,3,4-tetrahydronaphth-2,6-diyl; gps. (a) and (b) may be substd. by R1 and R2; Z1-2 = -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CH2CH2-, -CH=CH-, -CC- or a single bond; and m and n = 0, 1 or 2. (IV) is Na2B4O10, a borate-HCl buffer soln. or a B cpd. forming a borate in water. Reaction is carried out at pH 5-9, pref. at neutral pH. USE/ADVANTAGE - The process is suitable for the prodn. of liquid crystal (LC) cpds., esp. large scale prodn. of O-fluorophenyl derivs., and is safe and economical. All synthesis stages can be carried out in a temp. range easily controlled on the technical scale, i.e. at 20-100, pref. 70-90 deg.C, in contrast to the low temp. (-78 deg.C) used in the lithiation process. It also takes up to 90% less time, i.e. 3-4 h rather than 2 days by the classic process. Yields are up to 90% and the unreacted (II) can be recovered simply by recrystallisation.