Le Triflate de Bismuth(III) Comme Catalyseur Dans la Reaction de Carbonyl-Diels-Alder
摘要:
在三氟甲磺酸铋 (III) 存在下,羰基化的亲电子试剂(甲基草酸乙酯或乙醛酸乙酯)和普通二烯选择性地(60-100)导致杂羰基-Diels-Alder 反应与烯反应产物。Bi(OTf) 3 表现出很强的催化活性并且在温和的条件下反应。En présence de triflate de bismuth(III) le mésoxalate et le glyoxylate d'éthyle réagissent avec des diènes usuels pour donner un mélange de carbonyl-Diels-Alder et du produit de la ène réaction。Bi(OTf) 3 présente une forte activité catalytique et réagit dans des conditions douces。
The carbonyl-Diels-Alder reaction catalyzed by bismuth (III) chloride
作者:Hélène Robert、Bernard Garrigues、Jacques Dubac
DOI:10.1016/s0040-4039(97)10791-2
日期:1998.3
In presence of bismuth (III) chloride, a carbonylated electrophile (ethyl mesoxalate or glyoxylate) and usual diene led selectively (65 to 100%) the hetero carbonyl-Diels-Alder reaction with the ene reaction product. BiCl3 exhibits strong catalytic activity and, compared with previous literature, reacts under mild conditions.
Yb(OTf)(3), can catalyze the glyoxylate-ene reaction effectively as a water-stable and reusable catalyst. Moreover, the selectivity of DA product or ene product can be adjusted by solvents in the reaction of glyoxylates with a diene (isoprene). In the presence of chiral ytterbium complexes generated in situ from Yb(OTf)(3) and optical 6,6'-disubstituted binaphthols, methyl glyoxylate smoothly reacts with alpha-methyl styrene to afford alpha-hydroxyl esters in modest optical yields. (C) 1997 Elsevier Science Ltd.
Asymmetric Hetero Diels−Alder Reaction Catalyzed by Chiral Cationic Palladium(II) and Platinum(II) Complexes
The hetero Diels-Alder reaction of nonactivated conjugated dienes 1 with arylglyoxals 2 and glyoxylate esters 7 proceeded enantioselectively in the presence of a catalytic amount of cationic chiral BINAP-palladium or -platinum complexes and 3 Angstrom molecular sieves (MS3A). The addition of MS3A effectively improved the enantioselectivity of the reaction. Excellent ee's were obtained from the reactions of 2,3-dimethyl-1,3-butadiene (1a) and 1,3-cyclohexadiene (1d) with dienophiles 2 and 7. The square-planar structure of [Pd(S-BINAP)(PhCN)(2)](PF6)(2) was determined by X-ray diffraction, and a chiral induction model involving the square-planar palladium complex coordinated with BINAP and a dienophile is proposed.
Asymmetric hetero Diels-Alder reactions and ene reactions catalyzed by chiral copper(II) complexes
作者:Mogens Johannsen、Karl Anker Joergensen
DOI:10.1021/jo00123a007
日期:1995.9
A new copper(II) bisoxazoline-catalyzed reaction of glyoxylate esters with dienes leading to the hetero Diet-Alder product and the ene product in high yield and with a high enantiomeric excess (ee) has been developed. The hetero Diels-Alder product:ene product ratio is in the range 1:0.6 to 1:1.8 and is dependent on both the chiral ligand attached to the metal, the glyoxylate ester, and the reaction temperature. The scope of the copper(II) bisoxazoline-catalyzed reaction of glyoxylate esters with dienes is demonstrated by the reaction of a variety of different dienes with ethyl and isopropyl glyoxylate, and it is shown that a simple substrate such as 1,3-butadiene reacts to give the hetero Diels-Alder product in 55% yield with an ee of 87%. Furthermore, the synthetic application of the reaction is demonstrated by the synthesis of a highly interesting synthon for sesquiterpene lactones in high yield and diastereoselectivity, and with a very high ee from 1,3-cyclohexadiene and ethyl glyoxylate using a copper(II) bisoxazoline as the catalyst. A mechanism for the hetero Diels-Alder reaction, which accounts for the enantioselectivity in the reactions, is proposed.