Asymmetric Michael addition of malonates to enones catalyzed by a siloxy amino acid lithium salt

Yoshida, Masanori; Narita, Mao; Hirama, Keisuke; Hara, Shoji

doi:10.1016/j.tetlet.2009.10.033

Cited by 27 publications

(12 citation statements)

References 46 publications

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“…Thus adduct 8 has the S-configuration. This procedure appears, until now, the simplest available protocol in order to obtain the S-isomer of 8 [27].…”

Section: Malonates and Related 13-dicarbonylsmentioning

confidence: 99%

“…All malonates and cyclic enones react generally smoothly to generate adducts with high yields and excellent enantioselectivities, except 2-cyclopentenone, which gives 88%, 64%, 47% yield and 30%, 63%, 55% ee under Ley [21], Ye [24], and Yoshida [27] This difficulty has been overcome using a chiral diamine-acid combination catalyst in methanol [23]. At the HF/6-31G(d) level of theory, the transition states C has a minimum of energy over transition states, where methanol or malonate are not involved in hydrogen bonding with the catalyst.…”

Section: Malonates and Related 13-dicarbonylsmentioning

confidence: 99%

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Asymmetric Organocatalytic Reactions of α,β-Unsaturated Cyclic Ketones

2011

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Abstract:The 1,4-conjugate addition of nucleophiles to α,β-unsaturated carbonyl compounds represents one fundamental bond-forming reaction in organic synthesis. The development of effective organocatalysts for the enantioselective conjugate addition of malonate, nitroalkane and other carbon and heteroatom nucleophiles to cycloenones constitutes an important research field and has been explored in recent years. At the same time, asymmetric Diels-Alder reactions have been developed and often a mechanism has been demonstrated to be a double addition rather than synchronous. This review aims to cover literature up to the end of 2010, describing all the different organocatalytic asymmetric 1,4-conjugate additions even if they are listed as transfer hydrogenation, cycloadditions or desymmetrization of aromatic compounds.

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“…Thus adduct 8 has the S-configuration. This procedure appears, until now, the simplest available protocol in order to obtain the S-isomer of 8 [27].…”

Section: Malonates and Related 13-dicarbonylsmentioning

confidence: 99%

Section: Malonates and Related 13-dicarbonylsmentioning

confidence: 99%

Asymmetric Organocatalytic Reactions of α,β-Unsaturated Cyclic Ketones

2011

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“…7,8 In this context, we attempted the thio-Michael addition of benzyl mercaptan with 2-cyclohexen-1-one (2a) in the presence of the catalyst 1a (Scheme 1). The reaction slowly proceeded to give the desired Michael adduct, 3-(phenylmethylthio)cyclohexanone (3a); however, the enantioselectivity was quite low (7% ee).…”

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confidence: 99%

“…Unfortunately, the reaction of 2-cyclopenten-1-one (2c) was very slow even at 37 °C (Table 4, entry 5). 7,9 As for a Michael donor, it was found that an electron-deficient mercaptan gave lower enantioselectivity. For example, the reaction of 2a with 4-chlorophenylmethyl mercaptan afforded a Michael adduct 3d with 27% ee, while 4-methoxyphenylmethyl mercaptan afforded 3e with 50% ee (Table 4, entries 6 and 7).…”

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confidence: 99%

“…A plausible reaction mechanism for the thio-Michael addition of benzyl mercaptan with 2a using the catalyst 1f is depicted in Scheme 2. 7,11 The primary amino acid catalyst 1f reacted with 2a to give an α,β-unsaturated imine. Although (E)-and (Z)-stereoisomers can be formed, a relatively bulky methylene group comes to the lesshindered side rather than the vinyl group.…”

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confidence: 99%

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Organocatalytic asymmetric thio-Michael addition of arylmethyl mercaptans to cyclic enones by a primary amino acid

Yoshida

Ohno

Hara

2010

Tetrahedron Letters

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The Catalytic, Enantioselective Michael Reaction

et al. 2016

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The catalytic enantioselective Michael reaction is the conjugate addition of a resonance‐stabilized carbanion to an electron‐poor olefin (an αβ‐unsaturated carbonyl compound or a related derivative) mediated by substoichiometric amounts of a chiral catalyst that enables stereocontrol in the newly generated stereocenter(s). This reaction allows the direct enantioselective construction of substituted 1,5‐dicarbonyl compounds or related architectures through the appropriate selection of the enolizable carbonyl compound employed as pronucleophile and the Michael acceptor. A variety of catalyst architectures have been described that make it possible to carry out this reaction with superior levels of chemical efficiency and high enantio‐ and stereocontrol, and also under conditions that tolerate a wide variety of functional groups. Both transition metal catalysis and organocatalysis have been employed as methodological approaches for carrying out this reaction in an enantioselective manner. This chapter describes different catalytic systems and methods developed for achieving enantioselective Michael reactions through the end of 2012, including a detailed mechanistic explanation of the different generic modes of substrate activation operating with each type of catalyst and their associated stereochemical aspects. The intention is to provide researchers interested in applying this methodology to their own synthetic strategies with a suitable starting point for identifying an efficient synthetic approach. In addition, the preparation of selected catalysts that are excellent for a particular pairing of substrates in this reaction, together with practical experimental protocols are described and some examples in which these methodologies have been applied to total synthesis have been included. This chapter is limited exclusively to those examples in which the final Michael addition product is obtained after protonation of the conjugate addition intermediate and therefore, tandem, domino, or cascade processes initiated by Michael reactions lie outside the scope of this work. Supplemental references are provided for articles published after the 2012 cut‐off date through the first half of 2015.

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Asymmetric Michael addition of malonates to enones catalyzed by a siloxy amino acid lithium salt

Abstract: Abstract-Siloxy amino acid lithium salt, O-tert-butyldiphenylsilyl L-serine lithium salt, was found to be an effective catalyst for the asymmetric Michael addition reaction of malonates to enones.

Cited by 27 publications

References 46 publications

Asymmetric Organocatalytic Reactions of α,β-Unsaturated Cyclic Ketones

Asymmetric Organocatalytic Reactions of α,β-Unsaturated Cyclic Ketones

Organocatalytic asymmetric thio-Michael addition of arylmethyl mercaptans to cyclic enones by a primary amino acid

The Catalytic, Enantioselective Michael Reaction

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