Enantioselective synthesis of (−)-cytoxazone and (+)-epi-cytoxazone via Rh-catalyzed diastereoselective oxidative C–H aminations

Narina, Srinivasarao V.; Kumar, Talluri Siva; George, Shyla; Sudalai, Arumugam

doi:10.1016/j.tetlet.2006.11.016

Cited by 36 publications

(17 citation statements)

References 43 publications

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“…(S)-3-(p-Methoxybenzyloxy)-2-methylpropyl Carbamate (6a) According to the general procedure, 5a 32) (99 mg, 0.47 mmol) was treated with trichloroacetyl isocyanate (107 mg, 0.55 mmol) in dichloromethane (5 ml) and crude material was chromatographed on silica gel (30% EtOAc in hexane) to give 6a (111 mg, 94%) as colorless crystals, mp 47-49°C (EtOAc-hexane 4 (9 mg, 0.02 mmol) in dichloromethane (1.5 ml) was refluxed for 17 h. After the mixture was cooled to room temperature, it was passed through a short Celite pad and the filtrate was concentrated. The residue was chromatographed on silica gel (30% EtOAc in hexane) to give 7a (14 mg, 28%) and recovered 6a (11 …”

Section: Methodsmentioning

confidence: 99%

“…The solution was washed with saturated aqueous NH 4 Cl, water, and brine, dried (MgSO 4 ) and concentrated. The product was dissolved in pyridine (6 ml), hydroxylamine hydrochloride (245 mg, 3.52 mmol) was added and the resulting mixture was stirred at room temperature for 4 h. Most of the pyridine was removed under reduced pressure and the residue was dissolved in EtOAc.…”

Section: Dirhodium(ii)-catalyzed C-h Amination Of 6cmentioning

confidence: 99%

“…The mixture was diluted with EtOAc. The solution was washed with saturated aqueous NH 4 Cl, water, and brine, dried (MgSO 4 ) and concentrated. The residue was chromatographed on silica gel (25% EtOAc in hexane) to 12 (20 …”

Section: Dirhodium(ii)-catalyzed C-h Amination Ofmentioning

confidence: 99%

“…Metal catalyzed C-H amination [1][2][3][4] of carbamates and sulfonamides demonstrated by Du Bois' group and the other groups have become a powerful tool for this purpose in recent synthetic organic chemistry. In our recently reported stereoselective total synthesis of an immunomodulator (ϩ)-conagenin, 5,6) we applied dirhodium(II)-catalyzed C-H amination reaction of carbamate (2) derived from optically active methyl 2-methyl-3-hydroxypropanoate (1) to prepare its amethylserine moiety (4) (Chart 1).…”

mentioning

confidence: 99%

“…The C-H amination reaction proceeded more smoothly than that of ester derivative (10) 6) when 9 was treated with Rh 2 (tpa) 4 in the presence of potassium carbonate in dichloromethane at room temperature to give oxazolidinone (7c) in 54% yield (29% for 10). In this reaction, the starting 9 was consumed completely.…”

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confidence: 99%

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Dirhodium(II)-Catalyzed C-H Amination Reaction of (S)-3-(tert-Butyldimethylsilyloxy)-2-methylpropyl Carbamate: A Facile Preparation of Optically Active Monoprotected 2-Amino-2-methyl-1,3-propanediol

Yakura

Yoshimoto

Ishida

2007

CHEMICAL & PHARMACEUTICAL BULLETIN

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Dirhodium(II)-catalyzed C-H amination reaction of (S)-3-(tert-butyldimethylsilyloxy)-2-methylpropyl carbamate, which was easily prepared from methyl (S)-2-methyl-3-hydroxypropanoate, proceeded more smoothly than those of their 2-(methoxycarbonyl)propyl derivative to give the corresponding oxazolidinone in excellent yield. The resulting oxazolidinone was converted efficiently into both (R)-monoprotected and (S)-monoprotected 2-amino-2-methyl-1,3-propanediols.

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Section: Methodsmentioning

confidence: 99%

Section: Dirhodium(ii)-catalyzed C-h Amination Of 6cmentioning

confidence: 99%

Section: Dirhodium(ii)-catalyzed C-h Amination Ofmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Dirhodium(II)-Catalyzed C-H Amination Reaction of (S)-3-(tert-Butyldimethylsilyloxy)-2-methylpropyl Carbamate: A Facile Preparation of Optically Active Monoprotected 2-Amino-2-methyl-1,3-propanediol

Yakura

Yoshimoto

Ishida

2007

CHEMICAL & PHARMACEUTICAL BULLETIN

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Rhodium‐Catalyzed CH Aminations

Lebel

2010

Catalyzed Carbon‐Heteroatom Bond Formation

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The formation of CÀN bonds is an important transformation in organic synthesis, as the amine functionality is found in numerous natural products and plays a key role in many biologically active compounds [1]. Standard catalytic methods to produce CÀN bonds involve functional group manipulations, such as reductive amination of carbonyl compounds [2], addition of nucleophiles to imines [3], hydrogenation of enamides [4][5][6][7][8], hydroamination of olefins [9] or a CÀN coupling reaction [10,11]. Recently, the direct and selective introduction of a nitrogen atom into a CÀH bond via a metal nitrene intermediate has appeared as an attractive alternative approach for the formation of CÀN bonds [12][13][14][15][16][17][18][19][20][21][22][23][24].Copper-catalyzed decomposition of benzenesulfonyl azide in the presence of cyclohexene was the first reported evidence of a metal-catalyzed nitrene insertion reaction [25]. This seminal discovery was then followed by the pioneering work of Breslow and Gellman who introduced the use of iminoiodinanes as metal nitrene precursors as well as rhodium dimer complexes as catalysts [26,27]. They showed the formation of the corresponding benzosultam in 86% yield in the presence of rhodium (II) acetate dimer (Rh 2 (OAc) 4 ) via an intramolecular metal nitrene CÀH bond insertion reaction (Eq. (5.1)). 86% Rh 2 (OAc) 4 (5 mol%) MeCN, rt S N I Ph O O S NH O O ð5:1ÞM€ uller then intensively studied rhodium dimer complexes as catalysts for the intermolecular amination of alkanes using iminoiodinanes, typically PhI¼NTs and PhI¼NNs [28][29][30]. Good yields were obtained for amination of benzylic, allylic and tertiary CÀH bonds, which are the most reactive CÀH bonds towards metal nitrenes. For instance the amination of indane provided the corresponding benzylic amine in Catalyzed Carbon-Heteroatom Bond Formation. Edited

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Funktionalisierung von C‐H‐Bindungen: neue Synthesemethoden für Naturstoffe und Pharmazeutika

2012

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Die direkte Funktionalisierung von C‐H‐Bindungen in organischen Molekülen hat sich in jüngster Zeit zu einer wirksamen und idealen Methode entwickelt, mit der Kohlenstoff‐Kohlenstoff‐ und Kohlenstoff‐Heteroatom‐Bindungen geknüpft werden können. Der Aufsatz gibt einen Überblick über die Strategien, die durch Funktionalisierung von C‐H‐Bindungen eine rasche Synthese von biologisch aktiven Verbindungen wie Naturstoffen und pharmazeutischen Zielsubstanzen ermöglichen.

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Enantioselective synthesis of (−)-cytoxazone and (+)-epi-cytoxazone via Rh-catalyzed diastereoselective oxidative C–H aminations

Cited by 36 publications

References 43 publications

Dirhodium(II)-Catalyzed C-H Amination Reaction of (S)-3-(tert-Butyldimethylsilyloxy)-2-methylpropyl Carbamate: A Facile Preparation of Optically Active Monoprotected 2-Amino-2-methyl-1,3-propanediol

Dirhodium(II)-Catalyzed C-H Amination Reaction of (S)-3-(tert-Butyldimethylsilyloxy)-2-methylpropyl Carbamate: A Facile Preparation of Optically Active Monoprotected 2-Amino-2-methyl-1,3-propanediol

Rhodium‐Catalyzed CH Aminations

Funktionalisierung von C‐H‐Bindungen: neue Synthesemethoden für Naturstoffe und Pharmazeutika

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