Laboratory of Asymmetric Catalysis and Synthesis, EPFL SB ISIC LCSA, BCH 4305, 1015 Lausanne (Switzerland) http://isic.epfl.ch/lcsa.
Angew Chem Int Ed Engl. 2014 Aug 18;53(34):9064-7. doi: 10.1002/anie.201405508. Epub 2014 Jul 1.
β-Lactams are very important structural motifs because of their broad biological activities as well as their propensity to engage in ring-opening reactions. Transition-metal-catalyzed C-H functionalizations have emerged as strategy enabling yet uncommon highly efficient disconnections. In contrast to the significant progress of Pd(0)-catalyzed C-H functionalization for aryl-aryl couplings, related reactions involving the formation of saturated C(sp(3))-C(sp(3)) bonds are elusive. Reported here is an asymmetric C-H functionalization approach to β-lactams using readily accessible chloroacetamide substrates. Important aspects of this transformation are challenging C(sp(3))-C(sp(3)) and strain-building reductive eliminations to for the four-membered ring. In general, the β-lactams are formed in excellent yields and enantioselectivities using a bulky taddol phosphoramidite ligand in combination with adamantyl carboxylic acid as cocatalyst.
β-内酰胺因其广泛的生物活性以及易于开环反应的特性,是非常重要的结构基序。过渡金属催化的 C-H 功能化已经成为一种策略,可以实现罕见的高效断键。与 Pd(0)催化的 C-H 芳基-芳基偶联的显著进展形成鲜明对比的是,涉及形成饱和 C(sp(3))-C(sp(3))键的相关反应仍然难以实现。本文报道了一种使用易得的氯乙酰胺底物的不对称 C-H 官能化方法来合成β-内酰胺。这种转化的重要方面是具有挑战性的 C(sp(3))-C(sp(3))和应变构建的还原消除,以形成四元环。一般来说,使用大位阻的手性叔醇衍生的磷酰胺配体与金刚烷羧酸作为共催化剂,可以以优异的收率和对映选择性得到β-内酰胺。