126060-70-6Relevant articles and documents
Sc(OTf)3-catalyzed diastereoselective Friedel-Crafts reactions of arenes and hetarenes with 3-phenylglycidates
Wilcke, David,Bach, Thorsten
supporting information; experimental part, p. 6498 - 6503 (2012/09/08)
Five different para-substituted 3-phenylglycidates (3-phenyloxirane-2- carboxylates) were prepared and subjected to reactions with arenes and hetarenes under Lewis acid catalysis. Sc(OTf)3 was found to effectively (5 mol%) promote a Friedel-Crafts reaction in nitromethane as the solvent. The reaction was shown to proceed stereoconvergently, which makes the intermediacy of a benzylic cation likely. The diastereoselectivities varied depending on the choice of the nucleophile and 3-arylglycidate. Best results were obtained with tert-butyl 3-anisylglycidate, which delivered the respective products with high syn-preference in diastereomeric ratios (d.r.) between 82:18 and >95:5. The observed selectivity can be explained by a model, according to which the intermediate benzylic cations adopt a preferred conformation, which allows for diastereoface-differentiation by the adjacent stereogenic center.
Lipase-catalyzed transesterification as a practical route to homochiral syn-1,2-diols. The synthesis of the taxol side chain
Lee, Donghyun,Kim, Mahn-Joo
, p. 2163 - 2166 (2007/10/03)
syn-2,3-Dihydoxy-3-phenyl-propanoic acid methyl ester (1a) and its simple derivatives (1b-e) are efficiently resolved in LPS-catalyzed transesterification, leading to the synthesis of the taxol side chain and analogs from both resolved enantiomers.
Synthesis of taxoids II. Synthesis and antitumor activity of water-soluble taxoids
Harada, Naoyuki,Ozaki, Kunihiko,Yamaguchi, Tetsuo,Arakawa, Hiroaki,Ando, Akira,Oda, Kouji,Nakanishi, Noriyuki,Ohashi, Motoaki,Hashiyama, Tomiki,Tsujihara, Kenji
, p. 241 - 258 (2007/10/03)
Synthesis of novel taxoid water-soluble prodrugs that have 2′-substituted amino acid derivatives with spacer is described. Enantioselective synthesis of the C-13 side chains proceeded through the asymmetric dihydroxylation. Several compounds had good solubility in saline and showed potent antitumor activity against B16 melanoma in mice.
Enantioselective Catalytic Epoxidation of Cinnamate Esters
Jacobsen, Eric N.,Deng, Li,Furukawa, Yoshiro,Martinez, Luis E.
, p. 4323 - 4334 (2007/10/02)
A broad study of the (salen)Mn(III)-catalyzed asymmetric epoxidation of cis-cinnamate esters reveals that the steric properties of the ester group have a profound influence on enantioselectivity in the epoxidation reaction, with bulkier esters affording highest ee's.The sensitivity of the reaction selectivity to the steric properties of the cis-alkene are consistent with a "skewed" side-on approach of olefin to the metal -oxo.The electronic properties of the substrate arene ring substituents do not correlate with epoxidation ee, but instead with the cis/trans partitioning of product formation.Evidence is provided for a non-polar inter mediate in a stepwise oxygen-atom-transfer mechanism.The presence of pyridine N-oxide derivatives has a significant effect on catalysts rates and total turnovers, but negligible influence on the stereoselectivity of epoxidation.A mechanistic basis for the role of these additives is proposed.The synthetic applicability of the cinnamate epoxidation methodology is illustrated in the highly enantioslective synthesis of diltiazem.
Reactions of Methyl threo-2-Acetoxy-3-chloro-3-(4-methoxyphenyl)propanoate and Methyl cis-2,3-Epoxy-3-(4-methoxyphenyl)propanoate with 3,5-Dimethoxyphenol: Potential Routes to Flavan-3-ols
Brown, Roger. F. C.,Jackson, W. Roy,McCarthy, Tom D.,Fallon, Gary D.
, p. 1833 - 1843 (2007/10/02)
Attempted syntheses of flavan-3-ols by reaction of either methyl threo-2-acetoxy-3-chloro-3-(4-methoxyphenyl)propanoate (3) or methyl cis-2,3-epoxy-3-(4-methoxyphenyl)propanoate (14) with 3,5-dimethoxyphenol failed to give the required aryl ethers.Products usually were derived from C-alkylation of the electron-rich phenol although reaction of the chloro acetate (3) with the phenoxide ion gave the furanone (5).The single-crystal X-ray structures of methyl 4-hydroxy-3-(4-methoxyphenyl)-2-(4-methoxyphenylmethyl)-5-oxo-2,5-dihydrofuran-2-carboxylate and cis-3-hydroxy-5,7-dimethoxy-4-(4-methoxyphenyl)-3,4-dihydro-2H-1-benzopyran-2-one have been determined.
Asymmetric syntheses of (+)-diltiazem hydrochloride
Watson, Keith G.,Fung, Yik M.,Gredley, Matthew,Bird, Graham J.,Jackson, W. Roy,Gountzos, Helen,Matthews, Barry R.
, p. 1018 - 1019 (2007/10/02)
Efficient enantioselective syntheses of the important cardiac drug (+)-cis-(2S,3S)-diltiazem from (E)-methyl 4-methoxyphenylpropenoate via either the (2R,3S)- or (2S,3R)-enantiomers of threo-methyl 3-(4-methoxyphenyl)-2,3- dihydroxypropanoate are described.
REACTION OF 4-SUBSTITUTED BENZALDEHYDES AND ACETOPHENONES WITH CHLOROACETONITRILE
Svoboda, Jiri,Kocfeldova, Zuzana,Palecek, Jaroslav
, p. 822 - 832 (2007/10/02)
Under conditions of phase-transfer catalysis or in homogeneous solution of potassium tert-butoxide the title compounds give stereoisomeric mixtures of substituted 2,3-epoxy nitriles III and IV.Alkaline hydrolysis of epoxy nitriles IV afforded the corresponding 2-arylpropanals in low yields.On treatment with methanol and potassium carbonate, epoxy nitriles III and IV were converted into epoxy esters in good yields.
Reaction of 3-Phenylglycidic Esters. Part 1. Stereoselective Opening of the Oxirane Ring of trans-3-Phenylglycidic Esters with 2-nitrothiophenols and the Effects of Various Catalysts Thereon
Hashiyama, Tomiki,Inoue, Hirozumi,Konda, Mikihiko,Takeda, Mikio
, p. 1725 - 1732 (2007/10/02)
In the reaction of 2-nitrothiophenol (2) with trans-3-phenylglycidic esters carrying various substituents on the benzene ring, both reactivity and stereoselectivity of the oxirane ring-opening of the glycidates were markedly influenced by the electronic nature of the substituents.The presence of electron-donating groups was favourable for both reactivity and the preferential formation of cis-opening products, while the reverse was true for electron-withdrawing groups.As a result of our investigation on the catalytic effect of various Lewis acids in the reaction of the 4-methoxy derivative (1) with (2), tin compounds were found to be effective catalysts for cis-opening and readily produced the threo-nitro ester (3a), a key intermediate for the synthesis of diltiazem (5).Isolation of the crystalline complex (adduct A) from the reaction of (2) with SnCl4 and its efficient catalytic activity similar to that of SnCl4 suggest that the transition state involves co-ordination of tin derivatives both with (2) and the epoxy oxygen of (1) to cause highly specific cis-opening.
