Asymmetric hydrovinylation of 1-vinylcycloalkenes. Reagent control of regio- and stereoselectivity.
نویسندگان
چکیده
1-Vinylcycloalkenes undergo highly regio- and enantioselective (>98% ee) 1,4-hydrovinylation (HV) when treated with ethylene (1 atm) at room temperature in the presence of [(S,S)-2,4-bis-diphenylphosphinopentane (BDPP)]CoCl(2) (0.05 equiv) and methylaluminoxane. The minor 1,2-HV products, seen only in 1-vinylcyclohexene (~15%) and 1-vinylcycloheptene (2%), are formed as racemic mixtures. The corresponding Ni(II)-catalyzed HV reactions of these substrates give mostly the 1,2-adducts. Racemic 4-tert-butyl-1-vinylcyclohexene, when treated with Co[(S,S)-(BDPP)]Cl(2) and ethylene, undergoes a rare enantiodivergent reaction giving two diastereomers each in >98% ee.
منابع مشابه
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ورودعنوان ژورنال:
- Journal of the American Chemical Society
دوره 134 15 شماره
صفحات -
تاریخ انتشار 2012