A New Method of Preparing Acetals

Nieuwland, J. A.; Vogt, R. R.; Foohey, W. L.

doi:10.1021/ja01366a026

Cited by 54 publications

(11 citation statements)

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“…1). This method compares well with the earlier procedures catalyzed by Hg, 6,7) Pd, [8][9][10] Pt, 9,11,12) Au, [13][14][15][16][17][18][19][20][21][22] Ir [23][24][25][26] and Zn.…”

supporting

confidence: 73%

A Fluorinated Cobalt(III) Porphyrin Complex for Hydroalkoxylation of Alkynes

Ushimaru

Nishimura

Iwatsuki

et al. 2017

CHEMICAL & PHARMACEUTICAL BULLETIN

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A fluorinated cobalt(III) porphyrin complex [Co(TPFPP)- (Fig. 1). This method compares well with the earlier procedures catalyzed by Hg, 6,7) Pd, [8][9][10] Pt, 9,11,12) Au, [13][14][15][16][17][18][19][20][21][22] Ir [23][24][25][26] and Zn. 27)The active pentafluorophenylated Co III catalyst 1a was developed by structural modification of 1b used previously for alkyne hydration 2) (Fig. 1). Reaction of tetrakis(pentafluorophenyl) porphyrin (H 2 TPFPP) and cobalt(II) acetate 28) followed by aerobic oxidation in the presence of HNTf 2 and recrystallization from a mixture of chloroform, ethanol, and hexane afforded 1a in 67% yield. X-Ray structural analysis of 1a indicated that (1) the cobalt center adopts octahedral geometry, with porphyrin ligand in the equatorial positions and ethanol in the apical positions (Fig. 2); (2) Figure S1(a)].The catalyst 1a was found to be more reactive than 1b in the hydroalkoxylation of phenylacetylene (2a) with methanol (Table 1, entries 1 vs. 7). When a mixture of 2a (2.0 mmol), 1a (0.05 mol%), and HNTf 2 (0.18 mol%) in methanol (0.9 mL, 11 equiv) was heated at 70°C for 4 h under aerobic conditions, acetal 3a was obtained in 97% yield (entry 1).29) The initial turnover frequency (TOF) was 4000 h −1 (t=12 min). This value is comparable to those of gold catalysts and higher than those of catalysts based on other metals (entry 2). 30) Hydroalkoxylation of 2a in the absence of HNTf 2 required higher catalyst loading (entries 3 and 4). The reaction proceeded under N 2 atmosphere, but yielded 3a in a lower yield than that under air (entry 5 vs. entry 1). Double hydroalkoxylation of 2a at 27°C (room temperature) afforded acetal 3a in 97% yield (entry 6). Co III TPPCl [TPP=5,10,15, porphyrin] was less reactive than 1a and 1b (entry 8 vs. entries 1 and 7). The reaction hardly proceeded with analogous metal complexes such as Fe III TPPCl or Mn III TPPCl under otherwise identical conditions (entries 9 and 10).* To whom correspondence should be addressed. e-mail: h_naka@nagoya-u.jp

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“…1). This method compares well with the earlier procedures catalyzed by Hg, 6,7) Pd, [8][9][10] Pt, 9,11,12) Au, [13][14][15][16][17][18][19][20][21][22] Ir [23][24][25][26] and Zn.…”

supporting

confidence: 73%

A Fluorinated Cobalt(III) Porphyrin Complex for Hydroalkoxylation of Alkynes

Ushimaru

Nishimura

Iwatsuki

et al. 2017

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…The hydration of alkynes for the preparation of useful carbonyl motifs has been as one of the most efficient functionalization reactions of alkynes (Scheme ) Classical procedures for the hydration of alkynes usually involve the use of mercuric salts as catalysts under acidic conditions . Because of the high toxicity of Hg compounds, the use of other metal species as catalysts, including Fe, Ag, Au, Ru, Ti, Pd, Pt, Ir, etc., has been investigated in recent decades.…”

Section: Introductionmentioning

confidence: 99%

Carbonyl‐Oxygen‐Assisted KOMe‐Mediated Formal Hydration of 4‐Alkynones: Complete Regioselectivity in the One‐Pot Synthesis of 1,4‐Diketones under Mild Conditions

Bai

Zhang

et al. 2018

Eur J Org Chem

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An effective carbonyl‐oxygen‐assisted transition‐metal‐free approach was developed for the one‐pot synthesis of 1,4‐diketones through the formal hydration of 4‐alkynones with complete regioselectivity under mild conditions. The reaction tolerates a wide range of functional groups, and the corresponding functionalized 1,4‐diketones were obtained in moderate to excellent yields (up to 94 %). Importantly, the complete regioselectivity was attributed to the fact that 2,3‐dihydrofuran intermediates were obtained as single products through the 5‐exo‐dig cyclization of 4‐alkynones; this was supported by control and isotope‐labeling experiments.

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“…Monoesters can be prepared easily by refluxing malic acid, an alcohol, and boron trifluoride as a catalyst (9). With polyhydric alcohols and polycarboxylic aromatic acids, malic acid yields alkyd polyester resins (10) (see Alcohols, polyhydric; Alkyd resins).…”

Section: Reactionsmentioning

confidence: 99%

Hydroxy Dicarboxylic Acids

Blair

DeFraties

2000

Kirk-Othmer Encyclopedia of Chemical Technology

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Malic acid and tartaric acid are two hydroxy dicarboxylic acids of commercial significance. Thiomalic acid and derivatives of malic and tartaric acid are discussed briefly. For malic and tartaric acids, physical and chemical properties, manufacturing process, commercial significance, health and safety properties, and primary applications, including food, pharmaceutical, and industrial, are reviewed. The primary chemical reactions are summarized; chelation and corrosion are discussed. The primary chemical reactions are summarized; chelation and corrosion are discussed. The commercial production procedures for malic acid and tartaric acid are summarized. Compendial specifications ( Food Chemicals Codex , National Formulary ) for malic acid and tartaric acid are listed.

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A New Method of Preparing Acetals

Cited by 54 publications

References 0 publications

A Fluorinated Cobalt(III) Porphyrin Complex for Hydroalkoxylation of Alkynes

A Fluorinated Cobalt(III) Porphyrin Complex for Hydroalkoxylation of Alkynes

Carbonyl‐Oxygen‐Assisted KOMe‐Mediated Formal Hydration of 4‐Alkynones: Complete Regioselectivity in the One‐Pot Synthesis of 1,4‐Diketones under Mild Conditions

Hydroxy Dicarboxylic Acids

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