Ruthenium-Catalyzed Decarboxylative Allylation of Nonstabilized Ketone Enolates
摘要:
Bipyridyl(pentamethylcyclopentadienyl)ruthenium chloride is an efficient catalyst for the formal [3,3] rearrangement of allyl beta-ketoesters. The mechanism of the transformation involves formation of pi-allyl ruthenium intermediates, which are selectively attacked at the more substituted allyl terminus by freely diffusing enolates. Decarboxylation of beta-ketocarboxylates allows generation of enolates under extremely mild conditions.
Alkylation of silyl enolates with tert-alkyl or allylic fluorides proceeds smoothly in the presence of a catalytic amount of borontrifluoride to afford the corresponding carbonyl compounds. Allylation and reduction of alkylfluorides with allylsilane and hydrosilane, respectively, occur under BF3 catalysis.
Rhodium-Catalyzed Branched and Enantioselective Direct α-Allylic Alkylation of Simple Ketones with Alkynes
作者:Liyu Xie、Haijian Yang、Mingliang Ma、Dong Xing
DOI:10.1021/acs.orglett.0c00375
日期:2020.3.6
first direct branched-selective α-allylic alkylation of simple ketones with alkynes under rhodium and secondary amine cooperative catalysis. Through a rhodium-hydride-catalyzed allylic substitution pathway, a series of valuable γ,δ-unsaturated ketones are obtained with excellent regioselectivity in an atom-economic and byproduct-free manner. With a chiral BIPHEP ligand, high enantioselectivity has been
challenge to generate stereogenic centers enantio- and regioselectively. In this context, the decarboxylative Carroll rearrangement of allyl β-keto esters is particularly interesting, since chiral γ,δ-unsaturated ketones are obtained. Herein, we show that CpRu half-sandwich complexes can, with selected enantiopure pyridine-monooxazoline ligands, catalyze this transformation and afford complete conversions
Lewis acid/CpRu dual catalysis in the enantioselective decarboxylative allylation of ketone enolates
作者:David Linder、Martina Austeri、Jérôme Lacour
DOI:10.1039/b910475e
日期:——
The addition of a Lewisacidic metal triflate salt Mg(OTf)2 as co-catalyst in the CpRu-catalyzed decarboxylative allylation of in situ-generated ketone enolates allows the reaction to proceed at lower temperature with higher regio- and enantioselectivity. Even so-far-unreactive substrates react.