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Hisashi Yamamoto

Bio: Hisashi Yamamoto is an academic researcher from University of Chicago. The author has contributed to research in topics: Enantioselective synthesis & Aldol reaction. The author has an hindex of 54, co-authored 318 publications receiving 8271 citations. Previous affiliations of Hisashi Yamamoto include King Abdulaziz University & Nagoya University.


Papers
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TL;DR: In this paper, the highly enantioselective and O-selective nitroso aldol reaction of tin enolates 2 and nitro-sobenzene (1) has been developed with the use of (R)-BINAP−silver complexes as a catalyst.
Abstract: The highly enantioselective and O-selective nitroso aldol reaction of tin enolates 2 and nitrosobenzene (1) has been developed with the use of (R)-BINAP−silver complexes as a catalyst. After the va...

217 citations

Journal ArticleDOI
TL;DR: The first general organocatalytic Beckmann rearrangement of ketoximes into amides has been realized by the catalytic use of cyanuric chloride and acids such as HCl and ZnCl2 are effective as cocatalysts with cyanurics chloride.
Abstract: The first general organocatalytic Beckmann rearrangement of ketoximes into amides has been realized by the catalytic use of cyanuric chloride. Furthermore, acids such as HCl and ZnCl2 are effective as cocatalysts with cyanuric chloride. For example, azacyclotridecan-2-one, which is synthetically useful as a starting material for nylon-12, was prepared in quantitative yield by the Beckmann rearrangement of cyclododecanone oxime (100 mmol scale) catalyzed by cyanuric chloride (0.5 mol %) and ZnCl2 (1 mol %).

206 citations

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TL;DR: Arylboron compounds, such as tris(pentafluorophenyl)borane, have been used as a co-catalyst in metallocene-mediated olefin polymerization.

190 citations

Journal ArticleDOI
TL;DR: In this article, the reaction of primary-secondary diols with acetyl chloride in dichloromethane in the presence of 2,4,6-collidine, N,N-diisopropylethylamine, or 1,2, 2,6, 6, 6-pentamethylpiperidine (PMP) leads to corresponding primary monoacetates simply, conveniently and in good yields.
Abstract: Reaction of primary-secondary diols with acetyl chloride in dichloromethane in the presence of 2,4,6-collidine, N,N-diisopropylethylamine, or 1,2,2,6,6-pentamethylpiperidine (PMP) leads to the corresponding primary monoacetates simply, conveniently, and in good yields. In this way, other acyl chlorides, sulfonyl chlorides, and silyl chlorides in place of acetyl chloride also react with primary hydroxyl group selectively

175 citations


Cited by
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TL;DR: An overview of the basic photophysics and electron transfer theory is presented in order to provide a comprehensive guide for employing this class of catalysts in photoredox manifolds.
Abstract: In this review, we highlight the use of organic photoredox catalysts in a myriad of synthetic transformations with a range of applications. This overview is arranged by catalyst class where the photophysics and electrochemical characteristics of each is discussed to underscore the differences and advantages to each type of single electron redox agent. We highlight both net reductive and oxidative as well as redox neutral transformations that can be accomplished using purely organic photoredox-active catalysts. An overview of the basic photophysics and electron transfer theory is presented in order to provide a comprehensive guide for employing this class of catalysts in photoredox manifolds.

3,550 citations

Journal ArticleDOI
TL;DR: The finding that the amino acid proline is an effective asymmetric catalyst for the direct aldol reaction between unmodified acetone and a variety of aldehydes is reported.
Abstract: Most enzymatic transformations have a synthetic counterpart. Often though, the mechanisms by which natural and synthetic catalysts operate differ markedly. The catalytic asymmetric aldol reaction as a fundamental C-C bond forming reaction in chemistry and biology is an interesting case in this respect. Chemically, this reaction is dominated by approaches that utilize preformed enolate equivalents in combination with a chiral catalyst.1 Typically, a metal is involved in the reaction mechanism.1d Most enzymes, however, use a fundamentally different strategy and catalyze the direct aldolization of two unmodified carbonyl compounds. Class I aldolases utilize an enamine based mechanism,2 while Class II aldolases mediate this process by using a zinc cofactor.3 The development of aldolase antibodies that use an enamine mechanism and accept hydrophobic organic substrates has demonstrated the potential inherent in amine-catalyzed asymmetric aldol reactions.4 Recently, the first small-molecule asymmetric class II aldolase mimics have been described in the form of zinc, lanthanum, and barium complexes.5,6 However, amine-based asymmetric class I aldolase mimics have not been described in the literature.7 Here we report our finding that the amino acid proline is an effective asymmetric catalyst for the direct aldol reaction between unmodified acetone and a variety of aldehydes. Recently we developed broad scope aldolase antibodies that show very high enantioselectivities, have enzymatic rate accelerations, and use the enamine mechanism of class I aldolases.4 During the course of these studies, we found that one of our aldolase catalytic antibodies (Aldolase Antibody 38C2, Aldrich) is an efficient catalyst for enantiogroup-differentiating aldol cyclodehydrations of 2,6-heptanediones to give cyclohexenones, including the Wieland-Miescher ketone.8,9 These intramolecular reactions are also catalyzed by proline (Hajos-Eder-Sauer-Wiechert reaction)10 and it has been postulated that they proceed via an enamine mechanism.11 However, the proline-catalyzed direct intermolecular asymmetric aldol reaction has not been described. Further, there are no asymmetric small-molecule aldol catalysts that use an enamine mechanism.7 Based on our own results and Shibasaki’s work on lanthanum-based small-molecule aldol catalysts,4,6 we realized the great potential of catalysts for the direct asymmetric aldol reaction. We initially studied the reaction of acetone with 4-nitrobenzaldehyde. Reacting proline (30 mol %) in DMSO/acetone (4:1) with 4-nitrobenzaldehyde at room temperature for 4 h furnished aldol product (R)-1 in 68% yield and 76% ee (eq 1). This result

2,283 citations

Journal ArticleDOI
TL;DR: Alkylations with Phenols, Nitrogen Nucleophiles in AAA Total Synthesis, and Considerations for Enantioselective Allylic Alkylation are presented.
Abstract: A. Primary Alcohols as Nucleophiles 2931 B. Carboxylates as Nucleophiles 2931 C. Alkylations with Phenols 2932 IV. Nitrogen Nucleophiles in AAA Total Synthesis 2935 A. Alkylamines as Nucleophiles 2935 B. Azides as a Nucleophile 2936 C. Sulfonamide Nucleophiles 2937 D. Imide Nucleophiles 2938 E. Heterocyclic Amine Nucleophiles 2940 V. Sulfur Nucleophiles 2941 VI. Summary and Conclusions 2941 VII. Acknowledgment 2941 VIII. References 2942 I. Considerations for Enantioselective Allylic Alkylation

2,230 citations

Journal ArticleDOI
Chao-Jun Li1
TL;DR: Reaction of R,â-Unsaturated Carbonyl Compounds 3127: Reaction of R-UnSaturated Carbonies 3127 7.1.6.
Abstract: 4.2.8. Reductive Coupling 3109 5. Reaction of Aromatic Compounds 3110 5.1. Electrophilic Substitutions 3110 5.2. Radical Substitution 3111 5.3. Oxidative Coupling 3111 5.4. Photochemical Reactions 3111 6. Reaction of Carbonyl Compounds 3111 6.1. Nucleophilic Additions 3111 6.1.1. Allylation 3111 6.1.2. Propargylation 3120 6.1.3. Benzylation 3121 6.1.4. Arylation/Vinylation 3121 6.1.5. Alkynylation 3121 6.1.6. Alkylation 3121 6.1.7. Reformatsky-Type Reaction 3122 6.1.8. Direct Aldol Reaction 3122 6.1.9. Mukaiyama Aldol Reaction 3124 6.1.10. Hydrogen Cyanide Addition 3125 6.2. Pinacol Coupling 3126 6.3. Wittig Reactions 3126 7. Reaction of R,â-Unsaturated Carbonyl Compounds 3127

2,031 citations