Iridium complex-catalyzed addition of water and alcohols to non-activated terminal alkynes

Hirabayashi, Tomotaka; Okimoto, Yoshio; Saito, Akiyo; Morita, Masao; Sakaguchi, Satoshi; Ishii, Yasutaka

doi:10.1016/j.tet.2005.12.010

Cited by 61 publications

(30 citation statements)

References 16 publications

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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: 72%

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: 72%

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

Ushimaru

Nishimura

Iwatsuki

et al. 2017

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…In 2006 Ishii and co-workers reported an addition of alcohols to non-activated terminal alkynes catalyzed by [Ir(cod) 2 ](BF 4 ) in the presence of P(OR) 3 (R = Me, Et, iPr) and a Lewis acid (AlCl 3 , ZrCl 4 , etc.) [8]. The hydroalkoxylation reactions catalyzed by transition metals have been extensively reviewed [9].…”

Section: Introductionmentioning

confidence: 99%

Iridium-catalyzed addition of methanol to terminal alkynes

Konkol

Schmidt

Steinborn

2007

Journal of Molecular Catalysis A: Chemical

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“…The methoxy, methyl, ethyl and tert-butyl group remained stable during the photo reaction (Table 2, entry 2-5). The reactivity of aliphatic alkynes was relatively low so the hydration reaction of 1-heptyne and 1-decyne were performed at 50 o C ( Table 2, entry [8][9] Subsequently, the reaction mechanism was investigated. According to previous observations, the first step in catalytic hydration of alkynes could be the reactions of porphyrin rhodium(III) with alkynes producing the β-carbonyl alkyl rhodium porphyrins through the same pathway in analogous to the reaction of (TSPP)Rh III complex with olefins to produce β-methoxyalkyl complexes.…”

Section: Scheme 1 (Tspp)rh III Catalyzed Hydration Of Alkynesmentioning

confidence: 99%