The borrowing-hydrogen (or hydrogen autotransfer) process, where the catalyst dehydrogenates a substrate and formally transfers the H atom to an unsaturated intermediate, is an atom-efficient and environmentally benign transformation. Described here is an example of an asymmetric borrowing-hydrogen cascade for the formal anti-Markovnikov hydroamination of allyl alcohols to synthesize optically enriched
作者:Stefania F. Musolino、O. Stephen Ojo、Nicholas J. Westwood、James E. Taylor、Andrew D. Smith
DOI:10.1002/chem.201604788
日期:2016.12.23
The non‐enzymatic acylative kineticresolution of challenging aryl–alkenyl (sp2 vs. sp2) substituted secondaryalcohols is described, with effective enantiodiscrimination achieved using the isothiourea organocatalyst HyperBTM (1 mol %) and isobutyric anhydride. The kineticresolution of a wide range of aryl–alkenyl substituted alcohols has been evaluated, with either electron‐rich or naphthyl aryl
描述了具有挑战性的芳基-烯基(sp 2与 sp 2 )取代的仲醇的非酶酰化动力学拆分,并使用异硫脲有机催化剂 HyperBTM(1 mol%)和异丁酸酐实现了有效的对映区分。已经评估了各种芳基-烯基取代醇的动力学拆分,其中富电子或萘基芳基取代基与未取代的乙烯基取代基相结合,提供了最高的选择性( S =2-1980)。演示了使用该方案对模型芳基-乙烯基(sp 2与 sp 2 )取代的仲醇进行克级(2.5 g)动力学拆分,可获取每种产物对映体的 >1 g 99:1呃。
Ruthenium-Catalyzed Asymmetric Allylic Alkylation of Isatins
作者:Barry M. Trost、Christopher A. Kalnmals、Divya Ramakrishnan、Michael C. Ryan、Rebecca W. Smaha、Sean Parkin
DOI:10.1021/acs.orglett.0c00504
日期:2020.4.3
synthesis of chiral isatin derivatives. The catalyst, which is generated in situ from commercially available CpRu(MeCN)3PF6 and a BINOL-derived phosphoramidite, is both highly active (TON up to 180) and insensitive to air and moisture. Additionally, the N-alkylated isatins accessible using this methodology are versatile buildingblocks that are readily transformed into chiral analogs of achiral drug molecules
Highly chemo- and stereoselective borrowing hydrogen processes are reported in which various target products are obtained through fine-tuning of the reaction conditions. By employing a robust Ru-catalyst of minimal stereogenicity, both kineticresolution and asymmetric induction were achieved simultaneously through a borrowing hydrogen cascade.
Diastereoselective Construction of <i>trans</i>-2-Alkyl-6-aryl-3,6-dihydro-2<i>H</i>-pyrans via Dehydrogenative Cycloetherification Promoted by DDQ
作者:Heesun Yu、Ryangha Lee、Hyoungsu Kim、Dongjoo Lee
DOI:10.1021/acs.orglett.1c00154
日期:2021.2.5
A diastereoselective synthesis of trans-2-alkyl-6-aryl-3,6-dihydro-2H-pyrans has been described. Dehydrogenative cycloetherification of (E)-(±)-1-aryl-5-hydroxy-1-alkenes promoted by DDQ proceeded cleanly via 6-endo cyclization to afford trans-2-alkyl-6-aryl-3,6-dihydro-2H-pyrans (32 examples) in good yield (up to 89%) and with moderate to excellent diastereoselectivity (up to 99:1). The synthetic