Catalytic Asymmetric Heterodimerization of Ketenes
摘要:
In this Communication we describe an unprecedented catalytic asymmetric heterodimerization of ketenes of wide substrate scope. The alkaloid-catalyzed method provides access to ketene heterodimer beta-lactones and allows even two different monosubstituted ketenes to be cross-dimerized, with excellent enantioselectivity (17 examples with >= 90% ee) and excellent heterodimer regioselectivity observed in all cases.
Catalytic Asymmetric Synthesis of Ketene Heterodimer β-Lactones: Scope and Limitations
作者:Shi Chen、Ahmad A. Ibrahim、Nicholas J. Peraino、Divya Nalla、Mukulesh Mondal、Maxwell Van Raaphorst、Nessan J. Kerrigan
DOI:10.1021/acs.joc.6b01481
日期:2016.9.2
scope exploration, protocol innovations (including double in situ ketene generation for 7 examples), and an application to a cinnabaramide A intermediate are described. The addition of lithium perchlorate (1–2 equiv) as an additive to the alkaloid catalyst system was found to favor formation of the E isomer of the ketene heterodimer. Ten examples were formed with moderate to excellent (E)-olefin isomer
Catalytic Asymmetric Heterodimerization of Ketenes
作者:Ahmad A. Ibrahim、Divya Nalla、Maxwell Van Raaphorst、Nessan J. Kerrigan
DOI:10.1021/ja211678m
日期:2012.2.15
In this Communication we describe an unprecedented catalytic asymmetric heterodimerization of ketenes of wide substrate scope. The alkaloid-catalyzed method provides access to ketene heterodimer beta-lactones and allows even two different monosubstituted ketenes to be cross-dimerized, with excellent enantioselectivity (17 examples with >= 90% ee) and excellent heterodimer regioselectivity observed in all cases.