The adduct obtained upon consecutive treatment of 1,4-dienes with butyllithium in the presence of potassium tert-butoxide, chlorotri(isopropyloxy)titanium and a carbonyl compound contains the α-hydroxyalkyl group invariably and exclusively linked to the 3-position of the former diene. When chlorotri(isopropyloxy)titanium is replaced by the Duthaler-Hafner reagent [4R,5R)-chloro(cyclopentadienyl)(2,2-dimethyl-α,α,α′,α′-tetraphenyl-1,3-dioxolane-4,5-dimethanolato-O,O α )titanium] the reaction does not only occur regioselectively but also with appreciably high enantioselectivity.
在
叔丁醇钾、
氯三(异丙氧基)
钛和羰基化合物的存在下,用丁基
锂连续处理 1,4 二烯时得到的加合物含有δ-羟基烷基,该烷基无一例外地与前一个二烯的 3 位相连。当
氯三(异丙氧基)
钛被 Duthaler-Hafner 试剂[4R,5R)-chloro(cyclopentadienyl)(2,2-dimethyl-δ±,δ±,δ±′,δ±′-tetraphenyl-1,3-dioxolane-4、(2,2-二甲基-δ,δ,δ′,δ′-四苯基-
1,3-二氧戊环-4,5-二
甲醇-O,O δ)
钛]反应不仅具有区域选择性,而且具有明显的高对映选择性。