Enantio- and Diastereoselective Synthesis of <i>cis</i>-2-Aryl-3-methoxycarbonyl-2,3-dihydrobenzofurans via the Rh(II)-Catalyzed C−H Insertion Process

Saito, Hiroaki; Oishi, Hideto; Kitagaki, Shinji; Nakamura, Seiichi; Anada, Masahiro; Hashimoto, Shunichi

doi:10.1021/ol0267127

Cited by 153 publications

(111 citation statements)

References 35 publications

(20 reference statements)

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“…As seen in Scheme 9, loss of either feature results in the destruction of enantiocontrol. 129 This result reinforces previous findings by McKervey, who noted very low asymmetric induction for the synthesis of cis-disubstituted dihydrofurans from acyclic diazoacetate precursors.…”

Section: 1c Dihydrobenzofuran Synthesissupporting

confidence: 91%

“…In 2002, Hashimoto and coworkers reported the enantio-and diastereoselective synthesis of cis-2-aryl-3-methoxycarbonyl-2,3-dihydrobenzofurans 83 via rhodium(II) carboxylate-catalysed C-H insertion reactions. 129 The choice of catalyst in this study was seen to be key, with only the phthaloyl catalysts Rh 2 (S-PTTL) 4 and Rh 2 (S-BPTTL) 4 , both featuring a bulky tert-butyl substituent, providing exclusively the cis-isomer 84 with good enantioselectivity (Table 17, entries a-e). This high level of asymmetric induction was found to be preserved for the decomposition of aryl diazoacetates possessing electron-withdrawing or -donating groups in the para position on the benzene ring (Table 17, entries c-e).…”

Section: 1c Dihydrobenzofuran Synthesismentioning

confidence: 95%

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Catalytic asymmetric C–H insertion reactions of α-diazocarbonyl compounds

2010

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Section: 1c Dihydrobenzofuran Synthesissupporting

confidence: 91%

Section: 1c Dihydrobenzofuran Synthesismentioning

confidence: 95%

Catalytic asymmetric C–H insertion reactions of α-diazocarbonyl compounds

2010

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“…Of these catalysts, dirhodium(II) tetrakis[Nphthaloyl-(S)-tert-leucinate], Rh 2 (S-PTTL) 4 (1d), has proven to be the most universally efficient catalyst for a range of rhodium(II)-carbene transformations of a-diazo carbonyl compounds. [6][7][8][9][10][11] The effectiveness of 1d has been particularly well demonstrated in intramolecular C-H insertions, 6) double intramolecular C-H insertions, 7) enantiotopically selective aromatic C-H insertions, 8) intermolecular 1,3-dipolar cycloadditions via the generation of ester-carbonyl ylides, 9) and [2,3]-sigmatropic rearrangements via the intramolecular formation of allylic or propargylic oxonium ylides 10,11) with high levels of enantioselectivities up to 98% ee. However, a problem associated with the original synthesis of Rh 2 (S-PTTL) 4 involves product yield simply because the preparation of optically pure N-phthaloyl-(S)-tert-leucine (2) is not straightforward (vide infra).…”

mentioning

confidence: 99%

Practical Synthesis of Dirhodium(II) Tetrakis[N-phthaloyl-(S)-tert-leucinate]

Tsutsui

Abe

Nakamura

et al. 2005

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…[4][5][6][7][8][9] However, only limited success has been achieved for asymmetric insertions into O-H bond. 2,[10][11][12] Recently, Fu and Zhou independently reported asymmetric insertion reactions into alcoholic, 13) phenolic 14) and aquatic 15) O-H bonds with a-diazoacetate using chiral Cu(I) complexes.…”

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confidence: 99%

Chiral Induction by Cinchona Alkaloids in the Rhodium(II) Catalyzed O-H Insertion Reaction

Saito

Iwai

Uchiyama

et al. 2010

CHEMICAL & PHARMACEUTICAL BULLETIN

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The catalytic insertion reaction into O-H bond with a-diazocarbonyl compounds via a metal-carbenoid intermediate is a very useful organic transformation for the synthesis of oxygen-containing compounds.1-3) Remarkable advances, including enantioselective insertion, have been made in catalytic C-H insertions with a-diazocarbonyl compounds using Rh(II) complexes. [4][5][6][7][8][9] However, only limited success has been achieved for asymmetric insertions into O-H bond. 2,[10][11][12] Recently, Fu and Zhou independently reported asymmetric insertion reactions into alcoholic, 13) phenolic 14) and aquatic 15) O-H bonds with a-diazoacetate using chiral Cu(I) complexes. In contrast, chiral Rh(II) complexes gave poor enantioselectivity (8% ee) in the O-H insertion reaction, 11) while they have given remarkable results in the C-H insertion reaction. Since Rh(II) complexes are unique and powerful catalysts in the insertion reaction, we attempted to apply them to the enantioselective O-H insertion reaction.Recently, Liang et al. conducted a physicochemical approach to O-H insertion reactions using density functional theory (DFT). 10) They concluded that Rh(II) complex does not have enough affinity to the oxonium ylide intermediate to form firmly fixed stereocenter around the metal. Hence, we sought to design a novel approach to the enantioselective O-H insertion reaction catalyzed by Rh(II) complexes, independent of its own chirality. It is of interest that chiral amine additives expressed its own chirality on metal mediated epoxidation reaction using achiral Mn-salen complex. 16)Accordingly, we envisaged that an intermolecular O-H insertion of a-aryldiazoacetate and water should produce a mandelate in an enantioselective manner using cinchona alkaloids and Rh(II) complexes. Using this method, we now report that a combination of quinine (1) or quinidine (2) and dirhodium(II) tetra(triphenylacetate), Rh 2 (TPA) 4 , in the O-H insertion provides mandelate as the sole product in up to 50% ee.In our initial studies, we explored the intermolecular O-H insertion of methyl phenydiazoacetate in dichloromethane using 1 mol% of Rh 2 (TPA) 4 17,18) and 2 mol% of quinine (1) (Table 1, entry 1). [19][20][21][22] As expected, the reaction proceeded smoothly at 23°C to completion within 4 h, giving methyl mandelate in 82% yield. The enantioselectivity in this reaction was 38% ee, as determined by HPLC (Daicel Chiralcel OD-H). The preferred absolute stereochemistry was (S), which was established by comparing the sign of the optical rotation with the literature value.23) It is worth noting that enantioselectivity for a particular product was provided by the cinchona alkaloids, not by the rhodium catalyst. The enantiomeric induction in this system may be due to the formation of a chiral complex between rhodium-carbenenoid and cinchona alkaoid. To rule out the possibility that the reaction was catalyzed by quinine (1), we performed the reaction under identical conditions in the absence of Rh 2 (TPA) 4 and observed no background reaction. To ...

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Enantio- and Diastereoselective Synthesis of cis-2-Aryl-3-methoxycarbonyl-2,3-dihydrobenzofurans via the Rh(II)-Catalyzed C−H Insertion Process

Cited by 153 publications

References 35 publications

Catalytic asymmetric C–H insertion reactions of α-diazocarbonyl compounds

Catalytic asymmetric C–H insertion reactions of α-diazocarbonyl compounds

Practical Synthesis of Dirhodium(II) Tetrakis[N-phthaloyl-(S)-tert-leucinate]

Chiral Induction by Cinchona Alkaloids in the Rhodium(II) Catalyzed O-H Insertion Reaction

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