Diarylborinic Acids as Efficient Catalysts for Selective Dehydration of Aldols

Ishihara, Kazuaki; Kurihara, Hideki; Yamamoto, Hisashi

doi:10.1055/s-1997-3207

Cited by 61 publications

(33 citation statements)

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“…), which was orig-β-hydroxy carbonyl compounds. [10] The catalytic activities inally believed to be a non-chelating Lewis acid, afforded of diarylborinic acids 2 and 3 in Mukaiyama aldol reactions the α-methoxy alcohol as a major product. Similar results are much higher than those of the corresponding arylin terms of selectivity were also obtained with Me 3 Al in boronic acids.…”

Section: Diarylborinic Acidsmentioning

confidence: 99%

“…Furthermore, 2 is a stronger Lewis acid than pentafluorophenylboronic acid (4), although it is weaker than moval of water by the magnesium sulfate may prevent the hydrolysis of 2 and shift the equilibrium between the mix-1. [10] Several arylboron compounds bearing electron-with-ture of 2 and 16 and the mixture of the borinate and water in the direction of the borinate. drawing aromatic groups have been examined as catalysts for the OPP oxidation of (S)-perillyl alcohol (16).…”

Section: Diarylborinic Acidsmentioning

confidence: 99%

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Arylboron Compounds as Acid Catalysts in Organic Synthetic Transformations

Ishihara¹,

Yamamoto²

1999

Eur. J. Org. Chem.

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228

122

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Arylboron compounds, ArnB(OH)3–n (n = 1–3), bearing electron‐withdrawing aromatic groups such as triarylboranes, diarylborinic acids, and arylboronic acids represent a new class of air‐stable and water‐tolerant Lewis acid or Brønsted acid catalysts in organic synthesis. In particular, while tris(pentafluorophenyl)borane has primarily been used as a co‐catalyst in metallocene‐mediated olefin polymerization, its potential as a Lewis acid catalyst for organic transformation is now much more extensive. Diarylborinic acids and arylboronic acids have shown themselves to be powerful tools in the design of chiral boron catalysts. This article provides a comprehensive summary of the organic transformations catalyzed by arylboron compounds as acids.

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Section: Diarylborinic Acidsmentioning

confidence: 99%

Section: Diarylborinic Acidsmentioning

confidence: 99%

Arylboron Compounds as Acid Catalysts in Organic Synthetic Transformations

Ishihara¹,

Yamamoto²

1999

Eur. J. Org. Chem.

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228

122

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“…For example, poly[N,N′-(1,10-decanedicarboxyl)-2-imidazolidone] is directly synthesized by the reaction of 1,10-decanedicarboxylic acid with 2-imidazolidone in the presence of 5 mol% of 3,5-(CF 3 ) 2 …”

Section: Arylboronic Acidsmentioning

confidence: 99%

“…Ishihara and Yamamoto et al have found that (C 6 F 5 ) 2 BOH is a suitable OPP catalyst for primary and secondary allylic and benzylic alcohols [4]. (C 6 F 5 ) 2 BOH is prepared from (C 6 F 5 ) 2 BCl with aqueous 2 M HCl [5]. It is obtained as a white, microcrystalline solid that can be handled readily in air and is soluble in many organic solvents.…”

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confidence: 99%

Organoboronic Acids and Organoborinic Acids as Brønsted–Lewis Acid Catalysts in Organic Synthesis

Ishihara¹

2005

Boronic Acids

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“…Diarylborinic acids bearing electron-withdrawing aromatic groups are effective catalysts for Mukaiyama aldol condensation and the subsequent selective dehydration of P-hydroxy carbonyl compounds [163]. The catalytic activity of diarylborinic acids (C6F5)2BOH and (3,5-(CF3)2C6H3)2BOH in Mukaiyama aldol reactions are much higher than those of the corresponding arylboronic acids.…”

Section: Diarylborinic Acidmentioning

confidence: 99%

Achiral B(III) Lewis Acids

Ishihara¹

2000

Lewis Acids in Organic Synthesis

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The classical boron Lewis acids, BX3, RBX2 and R2BX (X = F, C1, Br, I, OTf) are now popular tools in organic synthesis. B(II1) can act as a Lewis acid because there is an empty p-orbital on the boron. Enthalpy values indicate that when pyridine is the reference base, the Lewis acidity of Group IIIB halides increase in the order A1X3 > BX3 > GaX3. The Lewis acidity of BX3 generally increases in the order fluoride < chloride < bromide < iodide, i.e. the exact reverse of the order expected on the basis of the relative o-donor strengths of the halide anions. The main reason for this anomaly is that in these BX3 compounds, the B-X bonds contain a n-component which is formed by overlap of a filled p-orbital on the halogen with the empty p-orbital on the boron. Because the latter orbital is used to form an o-bond when BX3 coordinates with a Lewis base, this n-component is completely destroyed by complex formation. The strength of the n-component now increases in the order iodide < bromide < chloride < fluoride, i.e. the amount of n-bond energy that is lost on complex formation increases as the atomic weight of the halogen decreases. Evidently, as far as the extent of complex formation is concerned, this is a more important factor than the corresponding decrease in the o-donor strength of the halogen.The BF3 and BC13 complexes of diethyl ether are less stable than those of dimethyl ether, and the same order of stability is observed for the complexes of diethyl and dimethyl sulfides. As expected, steric interaction decreases as the distance between the metal and ligand atom is increased. Thus, it decreases when the metal atom is changed from boron to aluminum, or when the ligand atom is changed from oxygen to sulfur.The major applications of BX3 Lewis acids in organic synthesis include dealkylation of ethers, condensation reactions, and as a catalyst for Friedel-Crafts-type reactions and other acid-related chemistry. In general, these are used stoichiometrically in organic transformations under anhydrous conditions, because the presence of even a small amount of water causes rapid decomposition or deactivation of the promoters. To obviate some of these inherent problems, the potential of arylboron compounds, Ar,B(OH),-3 ( n = 1-3), bearing electron-withdrawing aromatic groups as a new class of boron catalysts has recently been demonstrated. For example, tris(pentafluor0phenyl)borane, B(C6F5)3, is a convenient, commercially available Lewis acid of strength comparable with that of BF3, but without the problems associated with reactive B-F bonds. Although its primary commercial application is as a co-catalyst in metallocene-mediated olefin polymerization, its potential as a Lewis acid catalyst for organic transformations is now recognized as being much more extensive. Diarylborinic acids and arylboronic acids bearing electron-withdrawing aromatic groups are also highly effective Lewis acid catalysts.This chapter focuses on the synthetic applications of BX3 as Lewis acids and the organic transformations catalyzed by arylboron...

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Diarylborinic Acids as Efficient Catalysts for Selective Dehydration of Aldols

Cited by 61 publications

References 0 publications

Arylboron Compounds as Acid Catalysts in Organic Synthetic Transformations

Arylboron Compounds as Acid Catalysts in Organic Synthetic Transformations

Organoboronic Acids and Organoborinic Acids as Brønsted–Lewis Acid Catalysts in Organic Synthesis

Achiral B(III) Lewis Acids

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