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  • Chiral aldehyde catalysis e...
    Shen, Hao-Ran; Li, Chao-Xing; Jiang, Xin; Lin, Yao; Liu, Jian-Hua; Zhu, Fang; Wu, Zhu-Lian; Cai, Tian; Wen, Wei; He, Rong-Xing; Guo, Qi-Xiang

    Chemical science, 05/2023, Volume: 14, Issue: 21
    Journal Article

    The direct catalytic α-hydrocarbylation of readily available amino acids with halohydrocarbons is one of the most straightforward methods leading to α,α-disubstituted non-proteinogenic α-amino acid compounds. However, all the reported methodologies depend on N-protected amino acids as starting materials. Herein, we report on three highly efficient aldehyde-catalyzed direct α-hydrocarbylations of N-unprotected amino acid esters with aryl-, allyl-, and benzyl halides. By promoting a simple chiral BINOL-aldehyde catalyst or combining catalysts of a chiral aldehyde and Lewis acid ZnCl 2 , the asymmetric α-arylation, α-allylation, and α-benzylation of amino acid esters with the corresponding halohydrocarbons proceed smoothly, producing α,α-disubstituted α-amino acids in moderate-to-high yields and good-to-excellent enantioselectivities. The asymmetric α-arylation reaction can be applied in the formal synthesis of the clinical candidate compound (+)-AG-041R. Based on the results given by control experiments, three reaction models are proposed to illustrate the stereoselective-control outcomes. The direct asymmetric α-arylation, allylation and benzylation of NH 2 unprotected amino acid esters with aryl halides, allyl and benzyl chlorides are respectively achieved by chiral aldehyde catalysis.