Regio- and diastereoselective conjugate addition of Grignard reagents to aryl substituted α,β-unsaturated carbonyl compounds derived from Oppolzer's sultam
作者:Xiufang Cao、Fang Liu、Wenchang Lu、Gang Chen、Guang-Ao Yu、Sheng Hua Liu
DOI:10.1016/j.tet.2008.04.048
日期:2008.6
Asymmetric conjugate addition of Grignard reagents to aryl substituted α,β-unsaturatedcarbonylcompounds (1) has been achieved with great regioselectivity (>20:1) and good to excellent diastereoselectivity (de up to 98%). The nucleophilicity and stereospecific blockade of the Grignard reagents play a key role in controlling the regioselectivities and diastereoselectivities of the conjugate addition
A Versatile New Catalyst for the Enantioselective Isomerization of Allylic Alcohols to Aldehydes: Scope and Mechanistic Studies
作者:Ken Tanaka、Gregory C. Fu
DOI:10.1021/jo010792v
日期:2001.11.1
[Rh(cod)(2)]BF(4), serves as an effective catalyst for asymmetric isomerizations of allylic alcohols to aldehydes, furnishing improved yields, scope, and enantioselectivities relative to previously reported methods. The catalyst is air-stable and can be recovered at the end of the reaction. Mechanistic studies establish that the isomerization proceeds via an intramolecular 1,3-hydrogen migration and that
Asymmetric Hydrogenation of Allylic Alcohols Using Ir–N,P-Complexes
作者:Jia-Qi Li、Jianguo Liu、Suppachai Krajangsri、Napasawan Chumnanvej、Thishana Singh、Pher G. Andersson
DOI:10.1021/acscatal.6b02456
日期:2016.12.2
γ-disubstituted and β,γ-disubstituted allylicalcohols were prepared and successfully hydrogenated using suitable N,P-based Ir complexes. High yields and excellent enantioselectivities were obtained for most of the substrates studied. This investigation also revealed the effect of the acidity of the N,P–Ir-complexes on the acid-sensitive allylicalcohols. DFT ΔpKa calculations were used to explain the effect of
Efficient isomerization: The title reaction was catalyzed by the [RuCl2(S)‐tol‐binap}(R)‐dbapen}]/KOH system in ethanol at 25 °C (see scheme). A series of E‐ and Z‐configured aromatic and aliphatic allylic alcohols, including a simple primary alkyl‐substituted compound (E)‐3‐methyl‐2‐hepten‐1‐ol, were transformed into the chiral aldehydes with at least 99 % ee. dbapen=2‐dibutylamino‐1‐phenylethylamine
A method for producing, in a few simple steps, a specific optically active aldehyde represented by the general formula (1), in which * is an asymmetric carbon atom, includes asymmetrically isomerizing a specific allyl alcohol represented by the general formula (2) in the presence of a ruthenium complex and a base.