The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform
Yoshiro Yamashita - One of the best experts on this subject based on the ideXlab platform.
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photochemically and thermally induced free radical reactions of alpha beta epoxy Ketones with tributyltin hydride selective c alpha o bond cleavage of oxiranylmethyl radicals derived from alpha beta epoxy Ketones
Journal of Organic Chemistry, 1992Co-Authors: Eietsu Hasegawa, Kenyuki Ishiyama, Tomoyasu Kato, Takaaki Horaguchi, Takahachi Shimizu, Shoji Tanaka, Yoshiro YamashitaAbstract:Free-radical reactions of α,β-epoxy Ketones with tributyltin hydride have been studied. Thes substances were selectively converted to β-hydroxy Ketones under both photochemical and thermal conditions. The photoreaction is initiated by hydrogen abstraction of an epoxy ketone triplet from tributyltin hydride, while azoisobutyronitrile is used as an initiator for the thermal reaction
Kiitiro Utimoto - One of the best experts on this subject based on the ideXlab platform.
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trialkylborane as an initiator and terminator of free radical reactions facile routes to boron enolates via α carbonyl radicals and aldol reaction of boron enolates
Bulletin of the Chemical Society of Japan, 1991Co-Authors: Kyoko Nozaki, Koichiro Oshima, Kiitiro UtimotoAbstract:A variety of trialkylborane-induced reactions were examined for the preparation of the α-carbonyl radicals: (1) addition of alkyl radical to methyl vinyl ketone, (2) reduction of α-halo ketone, and (3) intramolecular radical addition to α,β-unsaturated carbonyl moiety. Trialkylborane reacted with α-carbonyl radicals to give boron enolates. The resulting boron enolates were efficiently trapped by carbonyl compounds to give β-hydroxy Ketones in good yields.
Eric N Jacobsen - One of the best experts on this subject based on the ideXlab platform.
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highly enantioselective direct conjugate addition of Ketones to nitroalkenes promoted by a chiral primary amine thiourea catalyst
Journal of the American Chemical Society, 2006Co-Authors: Hongbing Huang, Eric N JacobsenAbstract:Primary amine−thiourea derivative 1 is an active and highly enantioselective catalyst for the conjugate addition of Ketones to nitroalkenes. Broad substrate scope is described, with nitroalkenes bearing either aromatic or aliphatic substituents and a wide variety of Ketones shown to be useful reacting partners. Ethyl Ketones react preferentially, generating anti products with methyl-bearing stereocenters with good-to-excellent diastereoselectivity. An enamine mechanism is indicated, with cooperative activation of the electrophile by the thiourea and of the ketone by the primary amine.
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highly enantioselective conjugate additions to α β unsaturated Ketones catalyzed by a salen al complex
Journal of the American Chemical Society, 2005Co-Authors: Mark S Taylor, David N Zalatan, Andreas M Lerchner, Eric N JacobsenAbstract:Chiral (salen)Al complex 1a catalyzes the highly enantioselective conjugate addition of carbon- and nitrogen-based nucleophiles to acyclic α,β-unsaturated Ketones. This methodology is tolerant of substantial variation of the ketone structure, providing access to a wide range of useful chiral building blocks in high yield and enantiomeric excess. Synthetic manipulations of the conjugate addition products are demonstrated, including the straightforward preparation of β-amino Ketones and highly enantioenriched carbo- and heterocyclic compounds.
Eietsu Hasegawa - One of the best experts on this subject based on the ideXlab platform.
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Metal-Free, One-Pot, Sequential Protocol for Transforming α,β-Epoxy Ketones to β-Hydroxy Ketones and α-Methylene Ketones
Journal of Organic Chemistry, 2015Co-Authors: Eietsu Hasegawa, Saki Arai, Eiji Tayama, Hajime IwamotoAbstract:A new sequential, one-pot protocol for transforming 1,3-disubstituted 2,3-epoxy Ketones to β-hydroxy Ketones and α-methylene Ketones has been developed. Reaction of epoxy Ketones with boron trifluoride etherate (BF3·OEt2) generates the cationic intermediates by regioselective epoxide ring opening and an acyl shift. Then, a treatment of these cations with 2-aryl-1,3-dimethylbenzimidazolines (DMBIH) results in formation of 1,2-disubstituted 3-hydroxy Ketones. DMBIH serves as a hydride donor in the second step of this process. Finally, the β-hydroxy Ketones can be converted to 1,2-disubstituted 2-methylene Ketones by treatment with methanesulfonic acid or a combination of methanesulfonyl chloride and triethylamine. Importantly, the sequential steps involved in formation of the α-methylene ketone products can be carried out in one pot.
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photochemically and thermally induced free radical reactions of alpha beta epoxy Ketones with tributyltin hydride selective c alpha o bond cleavage of oxiranylmethyl radicals derived from alpha beta epoxy Ketones
Journal of Organic Chemistry, 1992Co-Authors: Eietsu Hasegawa, Kenyuki Ishiyama, Tomoyasu Kato, Takaaki Horaguchi, Takahachi Shimizu, Shoji Tanaka, Yoshiro YamashitaAbstract:Free-radical reactions of α,β-epoxy Ketones with tributyltin hydride have been studied. Thes substances were selectively converted to β-hydroxy Ketones under both photochemical and thermal conditions. The photoreaction is initiated by hydrogen abstraction of an epoxy ketone triplet from tributyltin hydride, while azoisobutyronitrile is used as an initiator for the thermal reaction
Kyoko Nozaki - One of the best experts on this subject based on the ideXlab platform.
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trialkylborane as an initiator and terminator of free radical reactions facile routes to boron enolates via α carbonyl radicals and aldol reaction of boron enolates
Bulletin of the Chemical Society of Japan, 1991Co-Authors: Kyoko Nozaki, Koichiro Oshima, Kiitiro UtimotoAbstract:A variety of trialkylborane-induced reactions were examined for the preparation of the α-carbonyl radicals: (1) addition of alkyl radical to methyl vinyl ketone, (2) reduction of α-halo ketone, and (3) intramolecular radical addition to α,β-unsaturated carbonyl moiety. Trialkylborane reacted with α-carbonyl radicals to give boron enolates. The resulting boron enolates were efficiently trapped by carbonyl compounds to give β-hydroxy Ketones in good yields.
