The mild reducing agent tetramethylammonium triacetoxyborohydride reduces acyclic P-hydroxy ketones to their corresponding anti diols with high diastereoselectivity. a-Alkyl substitution does not significantly affect the stereoselectivity of these reductions. In all cases examined, good to excellent yields of diastereomerically homogeneous diols were obtained. The mechanism of these reductions involves
温和的还原剂
四甲基铵三乙酰氧基硼氢化物以高非对映选择性将无环 P-羟基
酮还原为其相应的反二醇。α-烷基取代不会显着影响这些还原的立体选择性。在所有检查的情况下,都获得了良好到极好的非对映异构体均质二醇的产率。这些还原的机制涉及
三乙酰氧基硼氢化物阴离子将
乙酸盐与底物醇进行酸促进的
配体交换。所得
氢化物中间体,大概是烷
氧基
二乙酰氧基
硼氢化物,还原近端 OH 0 OH OH 0 Me,NHB(
OAc), Mew Me&OR - OR Me he