Cooperative titanocene and phosphine catalysis: Accelerated C-X activation for the generation of reactive organometallics
The study presented herein describes a reductive transmetalation approach toward the generation of Grignard and organozinc reagents mediated by a titanocene catalyst. This method enables the metalation of functionalized substrates without loss of functional group compatibility. Allyl zinc reagents and allyl, vinyl, and alkyl Grignard reagents were generated in situ and used in the addition to carbonyl substrates to provide the corresponding carbinols in yields up to 99%. It was discovered that phosphine ligands effectively accelerate the reductive transmetalation event to enable the metalation of C-X bonds at temperatures as low as -40 °C. Performing the reactions in the presence of chiral diamines and amino alcohols led to the enantioselective allylation of aldehydes.
Fleury, Lauren M.,Kosal, Andrew D.,Masters, James T.,Ashfeld, Brandon L.
p. 253 - 269
(2013/03/14)
Generation of allyl Grignard reagents via titanocene-catalyzed activation of allyl halides
A protocol for the generation of allyl Grignard reagents via the catalytic activation of allyl halides is described herein. Subsequent nucleophilic addition to carbonyl derivatives provided the desired homo allylic alcohols in excellent yields (84-99%). E
Fleury, Lauren M.,Ashfeld, Brandon L.
scheme or table
p. 2427 - 2430
(2010/07/04)
Organozinc generation via the titanium-catalyzed activation of alkyl halides
[Chemical Equation Presented] A protocol for the generation of organozinc reagents via catalytic activation of alkyl halides is described herein. Subsequent nucleophilic addition to carbonyl derivatives provided the desired products in good to excellent y
Fleury, Lauren M.,Ashfeld, Brandon L.
supporting information; experimental part
p. 5670 - 5673
(2010/03/01)
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