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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. [ABSTRACT FROM AUTHOR]

We report a catalytic asymmetric protocol for the preparation of chiral pyrrolidinones proceeding via a radical pathway. The chemistry exploits the combination of photoredox catalysis and Lewis base catalysis to realise the first example of asymmetric radical conjugate addition to α,β‐unsaturated anhydrides and esters. The reaction is initiated by photoredox activation of N‐arylglycines to generate, upon decarboxylation, α‐amino radicals. These radicals are then intercepted stereoselectively by α,β‐unsaturated acyl ammonium intermediates, whose formation is mastered by a chiral isothiourea organocatalyst. Cyclisation leads to catalyst turnover and formation of enantioenriched pyrrolidinones. The utility of the protocol was demonstrated with application to the synthesis of biologically‐active γ‐amino butyric acids. [ABSTRACT FROM AUTHOR]

The isothiourea-catalyzed enantioselective 1,6-conjugate addition of para-nitrophenyl esters to 2,6-disubstituted para-quinone methides is reported. para-Nitrophenoxide, generated in situ from initial N-acylation of the isothiourea by the para-nitrophenyl ester, is proposed to facilitate catalyst turnover in this transformation. A range of para-nitrophenyl ester products can be isolated, or derivatized in situ by addition of benzylamine to give amides at up to 99% yield. Although low diastereocontrol is observed, the diastereoisomeric ester products are separable and formed with high enantiocontrol (up to 94:6 er). [ABSTRACT FROM AUTHOR]