Palladium-catalyzed coupling reactions of (ArCH2)Ti(O-i-Pr)3 with aromatic or heteroaromatic bromides
作者:Shu-Ting Chang、Qinghan Li、Ruei-Tang Chiang、Han-Mou Gau
DOI:10.1016/j.tet.2012.03.072
日期:2012.5
Three benzyltitanium compounds of (ArCH2)Ti(O-i-Pr)3 (Ar = Ph (1a), 4-MeOC6H4 (1b), 4-FC6H4 (1c)) were prepared and used as benzyl nucleophiles for coupling reactions with aromatic or heteroaromatic bromides. The simple catalytic system of 1 mol % Pd(OAc)2 and 2 mol % PCy3 worked efficiently for a wide variety of aromatic bromides, producing diarylmethanes in good to excellent yields of up to 96%.
三种benzyltitanium的(ARCH化合物2)的Ti(O-我-Pr)3(Ar为Ph(上1A),4- MeOC 6 H ^ 4(1B),4-FC 6 H ^ 4(1C制备))中并用作苄基亲核试剂,用于与芳族或杂芳族溴化物偶联反应。1 mol%Pd(OAc)2和2 mol%PCy 3的简单催化系统可以有效地用于各种芳族溴化物,以高达96%的优异收率生产二芳基甲烷。受阻芳族溴化物或含有吸电子取代基的芳族溴化物的偶联反应在3-6小时的较长反应时间内较慢。溴吡啶,溴呋喃或溴噻吩的杂芳族溴化物与1a或1b的苄基试剂反应需要更长的反应时间12–24 h或更高的反应温度80°C,从而产生吡啶基,呋喃基和噻吩基-芳基甲烷中等产量。