60856-85-1Relevant articles and documents
Mo–Catalyzed One-Pot Synthesis of N-Polyheterocycles from Nitroarenes and Glycols with Recycling of the Waste Reduction Byproduct. Substituent-Tuned Photophysical Properties
Hernández-Ruiz, Raquel,Rubio-Presa, Rubén,Suárez-Pantiga, Samuel,Pedrosa, María R.,Fernández-Rodríguez, Manuel A.,Tapia, M. José,Sanz, Roberto
supporting information, p. 13613 - 13623 (2021/08/23)
A catalytic domino reduction–imine formation–intramolecular cyclization–oxidation for the general synthesis of a wide variety of biologically relevant N-polyheterocycles, such as quinoxaline- and quinoline-fused derivatives, and phenanthridines, is reported. A simple, easily available, and environmentally friendly dioxomolybdenum(VI) complex has proven to be a highly efficient and versatile catalyst for transforming a broad range of starting nitroarenes involving several redox processes. Not only is this a sustainable, step-economical as well as air- and moisture-tolerant method, but also it is worth highlighting that the waste byproduct generated in the first step of the sequence is recycled and incorporated in the final target molecule, improving the overall synthetic efficiency. Moreover, selected indoloquinoxalines have been photophysically characterized in cyclohexane and toluene with exceptional fluorescence quantum yields above 0.7 for the alkyl derivatives.
2-substituted-alkyl ether and liquid crystal composition
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, (2008/06/13)
A 2-substituted-alkyl ether having an optically active group and being useful as a component of ferroelectric liquid crystal compositions, and a liquid crystal composition containing the same are provided, which 2-substituted-alkyl ether is expressed by t
Stereoselective synthesis of 3-amino-4,5-dihydroxyaldehydes - A novel preparation of N-acetyl-L-daunosamine
Effenberger, Franz,Roos, Juergen
, p. 1085 - 1095 (2007/10/03)
A general route for the stereoselective synthesis of 3-amino-4,5-dihydroxyaldehydes, with almost any desired configuration at the three stereogenic centers, is described by applying a combination of enzymatic and chemical steps. L-Daunosamine 1, for example, the glycosidic fragment of many important anthracycline antibiotics has been prepared by this route starting from O-allyl-L-lactaldehyde (S)-6a. (R)-Hydroxynitrile lyase (HNL) catalyzed addition of HCN to (S)-6a yields the 2,3-dihydroxynitrile (2S,3S)-7a with high stereoselectivity (91% de) in 75% yield. The addition of allyl Grignard to the O-protected 2,3-dihydroxynitrile (2S,3S)-9a and subsequent hydrogenation of the imino intermediate leads to 4-amino-2,3-dihydroxy-1-heptene (4S,5S,6S)-12a, which after ozonization and deprotection gives N-acetylated L-daunosamine 14a in a total yield of 15% referring to (S)-6a. The general applicability of this chemoenzymatic multistep procedure is demonstrated in the stereoselective synthesis of the unnatural aminodeoxy sugar (2S,3S,4S)-14b, starting from isovaleraldehyde 3. Copyright (C) 2000 Elsevier Science Ltd.
C2-symmetric copper(II) complexes as chiral lewis acids. Catalytic enantioselective carbonyl - Ene reactions with glyoxylate and pyruvate esters
Evans, David A.,Tregay, Steven W.,Burgey, Christopher S.,Paras, Nick A.,Vojkovsky, Tomas
, p. 7936 - 7943 (2007/10/03)
The C2-symmetric complexes [Cu(S,S)-tert-butylbis(oxazolinyl)](SbF6)2 (2a), its bis(aquo) counterpart [Cu(S,S)-tert-butylbis(oxazolinyl)(H2O)2](SbF6)2 (4), and [Cu(S,S)-phenylbis(oxazolinyl)](OTf)2 (1c) have been shown to catalyze the enantioselective ene reaction between glyoxylate esters and various olefins. Monosubstituted, disubstituted, and trisubstituted olefins each react with ethyl glyoxylate in the presence of 0.2 - 10 mol % of catalysts 1, 2, and 4 to afford the ene products in good yield and enantioselectivity. Complex 2a has also been shown to catalyze the addition of 1,1-disubstituted olefins to methyl pyruvate in good yields (76-95%) and excellent enantioselectivies (≥98% ee). The synthetic utility of the glyoxylate - ene reaction was demonstrated by conversion of the resulting α-hydroxy ester into the corresponding methyl ester, free acid, Weinreb amide, and α-azido ester, all with no detectable racemization.
Rh-DuPHOS-catalyzed enantioselective hydrogenation of enol esters. Application to the synthesis of highly enantioenriched α-hydroxy esters and 1,2-diols
Burk, Mark J.,Kalberg, Christopher S.,Pizzano, Antonio
, p. 4345 - 4353 (2007/10/03)
The asymmetric hydrogenation of α-(acetyloxy)- and α- (benzoyloxy)acrylates 4 catalyzed by cationic rhodium-DuPHOS complexes has been examined. A wide range of substrates (4) were prepared via a convenient Horner-Emmons condensation protocol, and subsequently hydrogenated under mild conditions (60 psi of H2) at substrate-to-catalyst ratios (S/C) of 500. Overall, enol ester substrates 4 were reduced by the cationic Et-DuPHOS-Rh catalysts with very high levels of enantioselectivity (93-99% ee). Importantly, substrates 4 bearing β-substituents could be employed as E/Z isomeric mixtures with no detrimental effect on the selectivity. Labeling studies indicated that no significant E/Z isomerization of the substrates occurs during the course of these reactions. Details concerning optimization of the reaction, interesting solvent effects, and deprotection procedures for the synthesis of highly enantioenriched α-hydroxy esters and 1,2-diols also are provided.
Reductive Biotransformation of Carbonyl Compounds --- Application of Fungus Geotrichum sp. G38 in Organic Synthesis
Jian-Xin, Gu,Zu-Yi, Li,Guo-Qiang, Lin
, p. 5805 - 5816 (2007/10/02)
The microbial transformation of 2- and 3-oxo esters and diketones with Geotrichum sp.G38 and its application to the syntheses of the key intermediates of several bioactive compounds such as (R)-denopamine 8, (R)-fluoxetine 11 and (2S,3R)-sitophilate 14 were described.
2-substituted-alkyl ether and liquid crystal composition
-
, (2012/05/07)
A 2-substituted-alkyl ether having an optically active group and useful as a component of ferroelectric liquid crystal compositions and a liquid crystal composition containing the same are provided, which 2-substituted-alkyl ether is expressed by the form
Selective Reductions. 46. Effect of the Steric Requirement at the 2-Position of Apopinene on chiral Reductions. B-(Iso-2-ethylapopinocampheyl)- and B-(Iso-2-n-propylapopinocampheyl)-9-borabicyclononanes as Improved Reagents for the Chiral Reduction of α,β-Acetylenic Ketones ...
Brown, Herbert C.,Ramachandran, P. Veeraraghavan,Weissman, Steven A.,Swaminathan, S.
, p. 6328 - 6333 (2007/10/02)
B-(Iso-2-ethylapopinocampheyl)-9-borabicyclononane (Eapine-Borane, 7), and B-(Iso-2-n-propylapopinocampheyl)-9-borabicyclononane (Prapine-Borane, 9), prepared via the hydroboration of 2-ethylapopinene (6) or 2-n-propylapopinene (8), respectively, with 9-borabicyclononane, reduce prochiral α,β-acetylenic ketones and α-keto esters to the corresponding alcohols with significantly higher optical induction than does Alpine-Borane (1). (-)-2-n-Propylapopinene was synthesized by treating nopyl tosylate with dimethyl cuprate prepared in situ from methyllithium and cuprous iodide. (+)-2-n-Propylapopinene was synthesized by Schlosser metalation of (+)-α-pinene followed by treatment with ethyl iodide. 4-Phenyl-3-butyne-2-one was reduced to the corresponding propargylic alcohol in 89percent ee and 96percent ee by Eapine-Borane and Prapine-Borane, respectively, as compared to 82percent ee with Alpine-Borane.Similar improved results were realized in the reduction of other acetylenic ketones by Eapine-Borane and Prapine-Borane.Similar improvements in the optical yields were realized in the reduction of α-keto esters by Eapine-Borane.For example, while Alpine-Borane produced methyl and ethyl lactate in 92percent and 91percent ee, respectively, Eapine-Borane gave these alcohols in 97percent and 96percent ee, respectively.Unfortunately, Prapine-Borane shows no improvement in percent ee for the reduction of α-keto esters.The increase in the percent ee realized is tentatively attributed to the increased steric requirements of the alkyl group at the 2-position of apopinene.