异硫脲催化的酯的对映选择性α-烷基化反应：通过 1,6-共轭加成到醌甲基化物。
Isothiourea-Catalyzed Enantioselective α-Alkylation of Esters via 1,6-Conjugate Addition to -Quinone Methides.
机构信息
EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK.
Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
出版信息
Molecules. 2021 Oct 20;26(21):6333. doi: 10.3390/molecules26216333.
The isothiourea-catalyzed enantioselective 1,6-conjugate addition of -nitrophenyl esters to 2,6-disubstituted -quinone methides is reported. -Nitrophenoxide, generated in situ from initial -acylation of the isothiourea by the -nitrophenyl ester, is proposed to facilitate catalyst turnover in this transformation. A range of -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).
报道了异硫脲催化的对硝基苯基酯与 2,6-二取代-醌甲亚胺的对映选择性 1,6-共轭加成反应。据推测，-硝基苯氧负离子是由异硫脲初始酰化对硝基苯基酯原位生成的，它促进了这一转化中的催化剂循环。一系列对硝基苯酯产物可以被分离出来，或者通过加入苄胺原位衍生化，以高达 99%的收率得到酰胺。尽管观察到低的非对映选择性，但非对映异构体酯产物是可分离的，并且具有高的对映选择性（高达 94:6 er）。
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