An efficient of Grignard-type procedure for the preparation of gem-diallylated compound
An efficient and a new procedure for the conversion of various carboxylic acid derivatives into the corresponding gem-diallylated compound under mild reaction condition has been developed. The triallylaluminum mediated Grignard-type addition of carboxylic acid derivative was utilized as a key operation to affect the transformation. The procedure is operationally simple, giving good to excellent product yields for a broad range of substrates. The chemoselectivity and regioselectivity of triallylaluminum were also demonstrated.
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.
supporting information; experimental part
p. 2427 - 2430
(2010/07/04)
Synthesis of β,γ-unsaturated ketones from acid chlorides through carbon-pentamethylcyclopentadienyl bond formation and cleavage
Reaction of acid chlorides with lithium pentamethylcyclopentadienide afforded the corresponding pentamethyl-cyclopentadienyl ketones in high yield. These ketones were treated with an allylaluminum reagent to form the corresponding 3-butenyl alcohols. Removal of pentamethylcyclopentadiene upon heating or treatment with a catalytic amount of trichloroacetic acid yielded the corresponding β,γ-unsaturated ketones in good yields.