Light-Mediated Asymmetric Aliphatic C–H Alkylation with Hydrogen Atom Transfer Catalyst and Chiral Phosphoric Acid
作者:Zhen-Yao Dai、Zhong-Sheng Nong、Pu-Sheng Wang
DOI:10.1021/acscatal.0c00610
日期:2020.4.17
In the presence of tetrabutylammonium decatungstate and chiral spiro phosphoric acid, a light-mediated asymmetric C–Hfunctionalization of unactivated hydrocarbons with exocyclic enones has been established. A wide range of cycloalkanes, benzylic, and allylic hydrocarbons are tolerated. This protocol proceeds via a hydrogen atom transfer/radical addition/hydrogen abstraction/enantioselective protonation
Chiral Spiro Phosphoramide-Catalyzed Sulfa-Michael Addition/Enantioselective Protonation of Exocyclic Enones
作者:Yi-Pan Li、Shou-Fei Zhu、Qi-Lin Zhou
DOI:10.1021/acs.orglett.9b03615
日期:2019.12.6
A highly efficient asymmetric Michael addition of thiols to exocyclic enones was achieved by using chiral spiro phosphoramide catalysts. The precisely chiral control in the protonation of the enol intermediate ensured high enantioselectivity. The reaction features high activity (yields up to 99%, turnover numbers up to 8400) and high enantioselectivity (up to 97% ee) with a broad substrate scope, and
indole-containing cyclic ketones with an α-chiral center and features with high yields (up to 99%) and high enantioselectivities (up to 98% ee) for a broad substrate scope. Density functional theory calculations suggest that the spiro phosphoric acid initially catalyzed the addition reaction by acting as a Brønsted acid and then catalyzed an enantioselective proton-transfer reaction of the enol intermediate
N,N,N′-Trimethylallylthiourea promotes the intermolecularPauson–Khandreaction with alkynes in the presence of Co2(CO)8 and moderate pressure of CO followed by thiourea elimination allowing the formation of methylenecyclopentenone derivatives.
Rearrangement of Allylic and Propargylic Alcohols Catalyzed by the Combined Use of tetrabutylammonium perrhenate (VII) and p-toluenesulfonic acid
作者:Koichi Narasaka、Hiroyuki Kusama、Yujiro Hayashi
DOI:10.1016/s0040-4020(01)88874-8
日期:1992.1
Allylic rearrangement and/or dehydration reaction of allylic alcohols proceeds smoothly by the use of catalytic amounts of tetrabutylammonium perrhenate and p-toluenesulfonic acid hydrate. Treatment of propargylic alcohols with the catalysts at room temperature affords the rearranged products, α,β-unsaturated carbonyl compounds, while, β,γ-unsaturated ketones are obtained as main products by the reaction