A Desilylative Approach to Alkyl Substituted C(1)-Ammonium Enolates: Application in Enantioselective [2+2] Cycloadditions.
A Desilylative Approach to Alkyl Substituted C(1)-Ammonium Enolates: Application in Enantioselective [2+2] Cycloadditions.
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DOI：
10.1002/anie.202208800
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发表时间：
2022-09-19
影响因子：
16.6
通讯作者：
Smith, Andrew D.
中科院分区：
文献类型：
--
作者：
Wang, Yihong;Young, Claire M.;Liu, Honglei;Hartley, Will C.;Wienhold, Max;Cordes, David B.;Slawin, Alexandra M. Z.;Smith, Andrew D.
本文报道了用异硫氰酸酯HyperBTM催化α-甲硅烷基-α-烷基取代羧酸生成C（1）-烯醇化铵的反应。这种脱甲硅基方法赠款获得α-未取代和α-烷基取代的C（1）-铵烯醇化物，其通常难以通过依赖于去质子化的传统方法获得。该方法的范围和限制在用全氟烷基酮的对映选择性[2+2]-环加成方法（31个实例，高达96%产率和>99：1 er）以及用三氟甲基烯酮的选择性[2+2]-环加成（4个实例，高达75%产率和>99：1 er）中确立。初步的机理研究表明，该过程通过原位制备的（±）-α-甲硅烷基-α-烷基取代的酸酐的初始动力学拆分进行，而反应过程表现出整体的伪零级动力学。以α-甲硅烷基-α-烷基取代羧酸为原料，利用异硫氰酸酯HyperBTM催化生成未取代和烷基取代的C（1）-铵烯醇化物，并将其应用于对映选择性的[2+2]-环加成反应。
The catalytic generation of C(1)‐ammonium enolates from the corresponding α‐silyl‐α‐alkyl substituted carboxylic acids using the isothiourea HyperBTM is reported. This desilylative approach grants access to α‐unsubstituted and α‐alkyl substituted C(1)‐ammonium enolates, which are typically difficult to access through traditional methods reliant upon deprotonation. The scope and limitations of this process is established in enantioselective [2+2]‐cycloaddition processes with perfluoroalkylketones (31 examples, up to 96 % yield and >99 : 1 er), as well as selective [2+2]‐cycloaddition with trifluoromethyl enones (4 examples, up to 75 % yield and >99 : 1 er). Preliminary mechanistic studies indicate this process proceeds through an initial kinetic resolution of an in situ prepared (±)‐α‐silyl‐α‐alkyl substituted anhydride, while the reaction process exhibits overall pseudo zero‐order kinetics. The catalytic generation of unsubstituted and alkyl substituted C(1)‐ammonium enolates from α‐silyl‐α‐alkyl substituted carboxylic acids using the isothiourea HyperBTM has been developed and applied in enantioselective [2+2]‐cycloaddition reactions.
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影响因子：
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