Enantioselective chlorinative aldol reaction of α-substituted acroleins catalyzed by chiral phosphine oxides
摘要:
The enantioselective chlorinative aldol reaction of a-substituted acroleins with aldehydes catalyzed by chiral phosphine oxides is described. A hypervalent silicon complex-derived chloride adds to the alpha-substituted acroleins to form the corresponding silyl enol ethers in situ, which subsequently reacts with aldehydes to produce the alpha-chloromethyl aldol adducts bearing a quaternary stereogenic center in good yields and stereoselectivities. When activated by a phosphine oxide catalyst, trichlorosilyl triflate acts as an effective promoter for the chlorinative aldol reaction as well as the chloride source; this discovery enabled the enantioselective chlorinative aldol reaction of alpha-substituted acroleins. (C) 2017 Elsevier Ltd. All rights reserved.
A Mild One-Pot Reduction of Phosphine(V) Oxides Affording Phosphines(III) and Their Metal Catalysts
作者:Łukasz Kapuśniak、Philipp N. Plessow、Damian Trzybiński、Krzysztof Woźniak、Peter Hofmann、Phillip Iain Jolly
DOI:10.1021/acs.organomet.0c00788
日期:2021.3.22
metal-free reduction of a range of phosphine(V) oxides employing oxalyl chloride as an activating agent and hexachlorodisilane as reducing reagent has been achieved under mild reaction conditions. The method was successfully applied to the reduction of industrial waste byproduct triphenylphosphine(V) oxide, closing the phosphorus cycle to cleanly regenerate triphenylphosphine(III). Mechanistic studies and quantum
The cleavage of R2SiXY (R = alkyl, phenyl; X = H, Cl, Y = α-Np, Ph, Cl, H) by triflic acid is selective, leading to new difunctional silyltriflates, R2SiXOTf, with the relative ease of cleavage of Si-Y being, α-Np>Ph>Cl>H⪢Me, Et, But.
Trichlorosilyl triflate-promoted directedcross-aldolreaction between ketones in the presence of a chiral phosphine oxide as an organocatalyst is described. This is the first enantioselective cross-aldolreaction between simple ketones with good enantioselectivity.