- Asymmetric Synthesis of α,β-Unsaturated δ-Lactones through Copper(I)-Catalyzed Direct Vinylogous Aldol Reaction
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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.
- Zhang, Hai-Jun,Yin, Liang
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supporting information
p. 12270 - 12279
(2018/09/25)
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- The use of COP-OAc in the catalyst-controlled syntheses of 1,3-polyols
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An iterative strategy to the 1,3-polyol motif is described. The use of the catalytic asymmetric Overman esterification for the construction of all stereogenic centers is broadly examined as are the sequences to extend the developing polyol chain. The iterative strategies are applied to the total syntheses of rugulactone and polyrhacitides A and B. 1 Introduction 2 Results and Discussion 2.1 Chain Elongation via RCM (Cycle A) 2.2 Total Synthesis of Rugulactone 2.3 Chain Elongation via Ando Olefination (Cycle B) and Total Syntheses of Polyrhacitides A and B 2.4 Useful Variants 3 Conclusions. Georg Thieme Verlag Stuttgart. New York.
- Kirsch, Stefan F.,Klahn, Philipp,Menz, Helge
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p. 3592 - 3603
(2011/12/21)
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- Enzyme Assisted Synthesis of Enantiomerically Pure δ-Lactones
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Both enantiomers series of a wide variety of optically pure 6-alkylated δ-lactones - saturated as well as unsaturated - were prepared via an enzyme mediated route.The key reaction step is the nucleophilic ring opening of enantiomerically pure alkyl-oxiranes, accessible via the corresponding β-hydroxythioesters which can be obtained enantiomerically pure via enzyme catalyzed kinetic resolutions.
- Haase, Bernhard,Schneider, Manfred P.
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p. 1017 - 1026
(2007/10/02)
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