Guindon Y, Houde K, Prévost M, Cardinal-David B, Landry S R, Daoust B, Bencheqroun M, Guérin B
Institut de recherches cliniques de Montréal (IRCM), Bioorganic Chemistry Laboratory, 110 avenue des Pins Ouest, Montréal, Québec, Canada H2W 1R7.
J Am Chem Soc. 2001 Sep 5;123(35):8496-501. doi: 10.1021/ja010805m.
Reported herein is a strategy employing a Mukaiyama reaction in tandem with a hydrogen transfer reaction for the elaboration of propionate motifs. The nature of the protecting groups on the chiral beta-alkoxy aldehyde and the type of Lewis acid used are varied to modulate the stereochemical outcome of the tandem reactions. The mode of complexation is thus controlled (monodentate or chelate) for the Mukaiyama reaction to give access to either syn or anti aldol products, precursors of the free radical reduction reaction. The endocyclic effect is subsequently capitalized upon to control the hydrogen transfer step so that the syn-reduced product may be achieved. Proceeding with excellent yield and diastereoselectivity, the synthetic sequence proposed gives access to syn-syn and syn-anti propionate motifs. Also considered is a complementary approach using a chelation-controlled Mukaiyama reaction in tandem with a free radical allylation reaction under the control of the endocyclic effect that leads to the anti-anti product.
本文报道了一种策略，该策略采用向山反应与氢转移反应串联来构建丙酸酯基序。对手性β-烷氧基醛上保护基的性质以及所使用的路易斯酸的类型进行了改变，以调节串联反应的立体化学结果。因此，控制络合模式（单齿或螯合）用于向山反应，以获得顺式或反式羟醛产物，即自由基还原反应的前体。随后利用环内效应来控制氢转移步骤，从而获得顺式还原产物。所提出的合成序列以优异的产率和非对映选择性进行，可得到顺式-顺式和顺式-反式丙酸酯基序。还考虑了一种互补方法，即在环内效应的控制下，使用螯合控制的向山反应与自由基烯丙基化反应串联，从而得到反式-反式产物。
