Catalytic asymmetric 1,4-additions of 3-substituted oxindoles to beta-aryl, beta-heteroaryl, and beta-alkenyl nitroalkenes are described. A new homodinuclear Mn(2)(OAc)(2)-Schiff base 1 complex was required to realize high diastereo- and enantioselectivity. Mn(2)(OAc)(2)-1 (1-5 mol %) promoted the 1,4-additions in 99-83% yield, 96-85% ee, and >30:1-5:1 dr at room temperature, providing useful chiral
描述了催化不对称 1,4-加成 3-取代 oxindoles 到 β-芳基、β-杂芳基和 β-烯基硝基烯烃。需要一种新的同双核 Mn(2)(OAc)(2)-Schiff base 1 复合物来实现高非对映选择性和对映选择性。Mn(2)(OAc)(2)-1 (1-5 mol %) 以 99-83% 的产率、96-85% 的 ee 和 >30:1-5:1 dr 促进 1,4-加成室温下,为合成具有邻位季/叔碳立体中心的 β-氨基羟吲哚提供有用的手性构件。
A Stable Homodinuclear Biscobalt(III)-Schiff Base Complex for Catalytic Asymmetric 1,4-Addition Reactions of β-Keto Esters to Alkynones
Two metal cooperation: A homodinuclear Co2–Schiff basecomplex Co2(OAc)2–1 promoted the asymmetric 1,4‐addition of β‐keto esters to alkynones under solvent‐free conditions in air (see scheme). The reactions proceeded without air or moisture sensitivity in high yields and with high enantioselectivities (99–91 % ee) at room temperature under highly concentrated conditions (neat–20 M) with 0.1–2.5 mol %