Nickel/Bis(oxazoline)-Catalyzed Asymmetric Kumada Reactions of Alkyl Electrophiles: Cross-Couplings of Racemic alpha-Bromoketones
The first asymmetric Kumada reactions of alkyl electrophiles are described, specifically, cross-couplings of racemic α-bromoketones with aryl Grignard reagents. Several features of this investigation are of interest. First, the couplings proceed at remarkably low temperature (−40 or −60 °C), which e...
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| Format: | Article |
| Language: | English |
| Published: |
American Chemical Society,
2011-12-14T21:48:47Z.
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| Online Access: | Get fulltext |
| Summary: | The first asymmetric Kumada reactions of alkyl electrophiles are described, specifically, cross-couplings of racemic α-bromoketones with aryl Grignard reagents. Several features of this investigation are of interest. First, the couplings proceed at remarkably low temperature (−40 or −60 °C), which enables the asymmetric synthesis of racemization-prone alpha-arylketones. Second, dialkyl ketones undergo enantioselective coupling in good ee and yield. Third, readily available bis(oxazolines) are shown for the first time to be effective ligands for cross-couplings of alkyl electrophiles, thereby opening the door to new opportunities in asymmetric catalysis. National Institute of General Medical Sciences (U.S.) (Grant R01-GM62871) Merck Research Laboratories Novartis (Firm) |
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