Palladium catalyzed synthesis of heterocycles

Utimoto, Kiitirô

doi:10.1351/pac198355111845

Cited by 236 publications

(127 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: 74%

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: 74%

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

Ushimaru

Nishimura

Iwatsuki

et al. 2017

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…30,129 Thus, a seminal work on this topic is the synthesis of bicyclic 2,3-dihydrofuran 145 by intramolecular hydroalkoxylation of alkynol 144, a process catalyzed by PdCl 2 (5 mol%) in refluxing acetonitrile (Scheme 55). 132 However, 3-, 4-and 5-alkyn-1-ols led to mixtures of the expected dihydrofurans and dihydropyrans and ketones resulting from the hydration of the triple bond. A similar procedure when applied to β,γ-acetylenic ketones or 2-methoxy-3-alkyn-1-ols afforded the corresponding furans in good yields.…”

Section: Heterocyclesmentioning

confidence: 99%

“…A similar procedure when applied to β,γ-acetylenic ketones or 2-methoxy-3-alkyn-1-ols afforded the corresponding furans in good yields. 132 Other examples of the synthesis of furans are the palladium-catalyzed internal cyclization of (Z)-2-en-4-ynol, 151 However, it has been more frequent to prepare these kind of benzocondensed systems from o-iodinated phenols and terminal alkynes by the above mentioned in situ palladium-catalyzed Sonogashira coupling (see Section 6.1) followed by intramolecular cyclization. 155,156 An example is the preparation of benzofuran 154 by in situ formation of alkynylphenol intermediate 153 from iodophenol 152 and 2-methylbut-3-yn-2-ol under Sonogashira conditions, followed by intramolecular cyclization.…”

Section: Heterocyclesmentioning

confidence: 99%

Chemicals from Alkynes with Palladium Catalysts

2013

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“…[3] When chiral alcohols are used, e.g. those generated by employing optically pure epoxides, the ring closure proThere are a few reports in the literature [4] [5] [6] [7] [8] [9] on the Pd II -catalyzed cyclization of alkynols. Thus, it is known ceeds with complete retention of configuration.…”

mentioning

confidence: 99%

“…Thus, (Ϫ)-(S)-propene oxide furnishes chiral (S)-2,5-dimethyl-4-phen-that dihydrofurans may be formed by palladium-catalyzed cyclization of 4-alkyl-substituted alk-3-yn-1-ols by 5-endoylthio-2,3-dihydrofuran (5a) with excellent optical purity (99% ee), as determined by GLC analysis on a chiral cyclo-dig ring closure. [4] In contrast, bis(homo)propargylic alcohols with a terminal alkyl substituent on the CϪC triple dextrin phase.…”

mentioning

confidence: 99%