165277-39-4Relevant academic research and scientific papers
Intertwined Analytical, Experimental and Theoretical Studies on the Formation and Structure of a Copper Dienolate
Lecachey, Baptiste,Palais, Laetitia,de Courcy, Beno?t,Bouauli, Samira,Durandetti, Muriel,Oulyadi, Hassan,Harisson-Marchand, Anne,Maddaluno, Jacques,Gérard, Hélène,Vrancken, Emmanuel,Campagne, Jean-Marc
, p. 7942 - 7950 (2021/05/07)
The reaction of a silyl dienolate, a Cu(II) salt and TBAT yielding the corresponding copper dienolate is addressed. A combined NMR and cyclic voltammetry analysis first highlight the role of TBAT in the Cu(II) to Cu(I) reduction and the structure of the precatalytic species. From these first results a second set of NMR and theoretical studies enable the determination of the structure and the mechanism of formation of the copper dienolate catalytic species. Finally, we showed that that the copper catalyst promote the E/Z s-cis/s-trans equilibration of the silyl dienolate precursor through a copper dienolate intermediate. All of these results unveil some peculiarities of the catalytic and asymmetric vinylogous Mukaiyama reaction.
Asymmetric Synthesis of α,β-Unsaturated δ-Lactones through Copper(I)-Catalyzed Direct Vinylogous Aldol Reaction
Zhang, Hai-Jun,Yin, Liang
, p. 12270 - 12279 (2018/09/25)
A simple methodology for the asymmetric synthesis of chiral α,β-unsaturated δ-lactones was achieved by copper(I)-catalyzed direct vinylogous aldol reaction (DVAR) of β,γ-unsaturated esters and various aldehydes, including aromatic aldehydes, heteroaromatic aldehydes, α,β-unsaturated aldehydes, and aliphatic aldehydes. For aromatic and heteroaromatic aldehydes, a one-pot reaction consisting of DVAR, isomerization of the unsaturated carbon-carbon double bond from (E)-form to (Z)-form, and subsequent intramolecular transesterification was required to get the lactones in moderate to high yields with high enantioselectivity. For α,β-unsaturated and aliphatic aldehydes, the DVAR proceeded directly to afford the lactones in moderate yields with high enantioselectivity. In the DVAR, various functional groups were well tolerated. Moreover, the methodology was nicely applicable to the aldehyde group distributed in natural products, derivatives of natural product, and derivatives of drug molecules (atomoxetine and naproxen). The mechanism studies revealed that α-addition was reversible and not favored, which accounted for the excellent regioselectivity in the DVAR. The copper(I)-dienolate species generated through deprotonation was proposed to form an equilibrium with an allylcopper(I) species, which reacted with aldehydes to afford the DVAR products through a catalytic asymmetric allylation of aldehydes. Finally, the robustness of the present reaction was demonstrated by a gram-scale reaction, and the utility of the present methodology was showcased by the formal asymmetric synthesis of ezetimibe and fostriecin.
Rationally Designed Chiral Synthons Enabling Asymmetric Z- and E-Selective Vinylogous Aldol Reactions of Aldehydes
Padarti, Akhil,Han, Hyunsoo
, p. 1448 - 1452 (2018/03/09)
In a conceptually different approach, highly stereoselective 2-oxonia-Cope rearrangement reactions between rationally designed nonracemic vinylogous aldolation synthons and aldehydes are described to provide δ-hydroxy-α,β-unsaturated esters with excellent
A stereoselective approach to 1,3-amino alcohols protected as cyclic carbamates: Kinetic vs. thermodynamic control
Broustal, Garance,Ariza, Xavier,Campagne, Jean-Marc,Garcia, Jordi,Georges, Yohan,Marinetti, Angela,Robiette, Raphael
, p. 4293 - 4297 (2008/03/18)
Direct enantiocontrolled access to 1,3-amino alcohols protected as cyclic carbamates is described. The approach is based on the addition of a silyl dienolate to aldehydes in the presence of 10 % of Carreira's catalyst (vinylogous Mukaiyama-aldol addition)
Efficient total syntheses and structural verification of both diospongins A and B via a common δ-lactone intermediate
Sawant, Kailas B.,Jennings, Michael P.
, p. 7911 - 7914 (2007/10/03)
(Chemical Equation Presented) The total syntheses of the two aryl C-glycoside natural products diospongins A and B are described. The key reactions involved stereoselective reductions of the appropriate oxocarbenium cations that were derived from a common
α,β-unsaturated δ-lactones from copper-catalyzed asymmetric vinylogous mukaiyama reactions of aldehydes: Scope and mechanistic insights
Bazan-Tejeda, Belen,Bluet, Guillaume,Broustal, Garance,Campagne, Jean-Marc
, p. 8358 - 8366 (2007/10/03)
A direct regio-, diastereo-, and enantiocontrolled access to α,β-unsaturated δ-lactones is described, based on the reaction of a silyl dienolate and an aldehyde in the presence of 10% of Carreira's catalyst. The scope and limitations of this reaction, as well as mechanistic insights concerning the reactivity of an allyl copper species, are discussed.
Preparation and Reactions of Diorganozincs from Dienic Silyl Enol Ethers
Devasagayaraj, A.,Schwink, L.,Knochel, P.
, p. 3311 - 3317 (2007/10/02)
The hydroboration of the dienic silyl enol ethers 1a-d with Et2BH produces organoboranes which are readily converted under mild conditions by a treatment with Et2Zn to the corresponding dialkylzincs 2a-d.These organometallics react after transmetallation with CuCN*2LiCl with various electrophiles affording polyfunctional silyl enol ethers of type 4.In the presence of the chiral catalyst (1R,2R)-bis(trifluoromethanesulfonamido)cyclohexane 6, the dialkylzinc 2b was added to various aldehydes leading to hydroxy silyl enol ethers of type 8 in satisfactory yields (45-77percent) and excellent enantioselectivities (85 to >96percent ee).The chiral products 8 can be oxidatively cyclized using t-BuOOH and catalytic amounts of VO(acac)2 furnishing trisubstituted tetrahydopyrans like 9a,b with high diastereoselectivity.An iodoalkoxylation of 8a affords after HI elimination and Jones oxidation the unsaturated valerolactone 13.
