Author
Minoru Uemura
Other affiliations: University of California, Berkeley
Bio: Minoru Uemura is an academic researcher from Kyoto University. The author has contributed to research in topics: Pentamethylcyclopentadiene & Coupling reaction. The author has an hindex of 6, co-authored 16 publications receiving 239 citations. Previous affiliations of Minoru Uemura include University of California, Berkeley.
Topics: Pentamethylcyclopentadiene, Coupling reaction, Aryl, Alkyl, Catalysis
Papers
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TL;DR: The first transition metal catalyzed asymmetric carboalkoxylation reaction of propargyl esters is described and experimental evidence supports a mechanism proceeding via the generation of a stabilized carbocation from an allylic oxonium intermediate and subsequent trapping by a chiral allylgold(I) spieces.
Abstract: The first transition metal catalyzed asymmetric carboalkoxylation reaction of propargyl esters is described. The (R)-MeO-DTBM-BIPHEP(AuCl)2-catalyzed reactions allow for the construction of benzopyrans containing quaternary stereocenters with excellent enantioselectivity. Experimental evidence supports a mechanism proceeding via the generation of a stabilized carbocation from an allylic oxonium intermediate and subsequent trapping by a chiral allylgold(I) spieces.
147 citations
TL;DR: Aryl bromides react with primary alkyl Grignard reagents in the presence of N,N,N′, N′-tetramethyl-1,3-propanediamine and catalytic amounts of cobalt(II) chloride and an N-heterocyclic carbene as mentioned in this paper.
Abstract: Aryl bromides react with primary alkyl Grignard reagents in the presence of N,N,N′,N′-tetramethyl-1,3-propanediamine and catalytic amounts of cobalt(II) chloride and an N-heterocyclic carbene to yi...
29 citations
TL;DR: A new ligand, Cp*CH2PPh2 (Cp* = 1,2,3,4,5-pentamethyl-2,4-cyclopentadienyl), was prepared, and was used as a ligand for nickel-catalysed cross-coupling reaction of alkyl halides with aryl Grignard reagents, which nickel-phosphine complexes had never made possible.
25 citations
TL;DR: The reaction of aryl-X or alkenyl-X (X=I, Br, OTf, ONf) with terminal acetylenes in the presence of a catalytic amount of Pd(OAc)2 provided the alkynylated products in good yields by using Cp ∗Li (Cp∗=1,2,3,4,5,5-pentamethylcyclopentadienyl) as a base as mentioned in this paper.
16 citations
TL;DR: In this paper, the carbinol returns to the parent aldehyde and pentamethylcyclopentadiene by the action of a catalytic amount of 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ).
9 citations
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TL;DR: Gold(I) complexes selectively activate π-bonds of alkenes in complex molecular settings, which has been attributed to relativistic effects as discussed by the authors, and are the most effective catalysts for the electrophilic activation of alkynes under homogeneous conditions.
Abstract: 1.1. General Reactivity of Alkyne-Gold(I) Complexes
For centuries, gold had been considered a precious, purely decorative inert metal. It was not until 1986 that Ito and Hayashi described the first application of gold(I) in homogeneous catalysis.1 More than one decade later, the first examples of gold(I) activation of alkynes were reported by Teles2 and Tanaka,3 revealing the potential of gold(I) in organic synthesis. Now, gold(I) complexes are the most effective catalysts for the electrophilic activation of alkynes under homogeneous conditions, and a broad range of versatile synthetic tools have been developed for the construction of carbon–carbon or carbon–heteroatom bonds.
Gold(I) complexes selectively activate π-bonds of alkynes in complex molecular settings,4−10 which has been attributed to relativistic effects.11−13 In general, no other electrophilic late transition metal shows the breadth of synthetic applications of homogeneous gold(I) catalysts, although in occasions less Lewis acidic Pt(II) or Ag(I) complexes can be used as an alternative,9,10,14,15 particularly in the context of the activation of alkenes.16,17 Highly electrophilic Ga(III)18−22 and In(III)23,24 salts can also be used as catalysts, although often higher catalyst loadings are required.
In general, the nucleophilic Markovnikov attack to η2-[AuL]+-activated alkynes 1 forms trans-alkenyl-gold complexes 2 as intermediates (Scheme 1).4,5a,9,10,12,25−29 This activation mode also occurs in gold-catalyzed cycloisomerizations of 1,n-enynes and in hydroarylation reactions, in which the alkene or the arene act as the nucleophile.
Scheme 1
Anti-Nucleophilic Attack to η2-[AuL]+-Activated Alkynes
1,260 citations
TL;DR: Application to Total Synthesis 1699 6.1.
Abstract: A.L.-P. thanks CSIC for a contract under the JAE-doctor
program. Financial support by PLE2009 project from MCIINN
and Consolider-Ingenio 2010 (proyecto MULTICAT) are also
acknowledged.
1,125 citations
TL;DR: This critical review intends to familiarize the reader with the essence of pi-acid catalysis, in particular with reactions or reaction cascades effected by gold and platinum complexes.
Abstract: This critical review intends to familiarize the reader with the essence of π-acid catalysis, in particular with reactions or reaction cascades effected by gold and platinum complexes. Even though materialized in apparently different reactivity modes, such noble metal catalyzed processes can be easily rationalized on the basis of a uniform mechanistic scheme that is outlined in detail. The resulting increase in molecular complexity is illustrated by selected natural product total syntheses and the formation of various intricate non-natural compounds (106 references).
995 citations
TL;DR: Alkenylation of Acetylenic Grignard Reagents 1447 6.1.3.
Abstract: 3.1.2. From Vinylic Grignard Reagents 1437 3.1.3. From Aryl Halides and Alkenyl Acetates 1438 3.2. Aryl-Aryl Cross-coupling 1438 3.2.1. From Aromatic Organometallic Reagents 1438 3.2.2. From Two Aromatic Halides 1440 4. Csp2-Csp3 Cross-coupling Reactions 1440 4.1. Alkenylation 1440 4.1.1. From Aliphatic Organometallic Reagents 1440 4.1.2. From Aliphatic Halides 1442 4.2. Arylation 1442 4.2.1. From Aliphatic Halides 1442 4.2.2. From Aromatic Halides 1445 4.3. Allylation of Aromatic Organometallics 1446 5. Alkynylation 1446 5.1. Pioneering Works 1446 5.2. Benzylation of Acetylenic Grignard Reagents 1446 5.3. Alkylation of Acetylenic Grignard Reagents 1447 5.4. Alkenylation of Acetylenic Grignard Reagents 1447 6. Csp3-Csp3 Cross-coupling 1448 6.1. Allylation 1448 6.1.1. Allylation of Aliphatic Organozinc Compounds 1448
504 citations
TL;DR: In the past several years, applications of transition metal complexes in tuning the reactivity of organocatalyst-promoted transformations have attracted increasing attention in the synthetic community as discussed by the authors.
499 citations