131029-02-2Relevant articles and documents
Broad Scope Synthesis of Ester Precursors of Nonfunctionalized Chiral Alcohols Based on the Asymmetric Hydrogenation of α,β-Dialkyl-, α,β-Diaryl-, and α-Alkyl-β-aryl-vinyl Esters
León, Félix,González-Liste, Pedro J.,García-Garrido, Sergio E.,Arribas, Inmaculada,Rubio, Miguel,Cadierno, Victorio,Pizzano, Antonio
, p. 5852 - 5867 (2017/06/07)
The catalytic asymmetric hydrogenation of trisubstituted enol esters using Rh catalysts bearing chiral phosphine-phosphite ligands (P-OP) has been studied. Substrates covered comprise α,β-dialkyl, α-alkyl-β-aryl, and α,β-diarylvinyl esters, the corresponding hydrogenation products being suitable precursors to prepare synthetically relevant chiral nonfunctionalized alcohols. A comparison of reactivity indicates that it decreases in the order: α,β-dialkyl > α-alkyl-β-aryl > α,β-diaryl. Based on the highly modular structure of P-OP ligands employed, catalyst screening identified highly enantioselective catalysts for α,β-dialkyl (95-99% ee) and nearly all of α-alkyl-β-aryl substrates (92-98% ee), with the exception of α-cyclohexyl-β-phenylvinyl acetate which exhibited a low enantioselectivity (47% ee). Finally, α,β-diarylvinyl substrates showed somewhat lower enantioselectivities (79-92% ee). In addition, some of the catalysts provided a high enantioselectivity in the hydrogenation of E/Z mixtures (ca. Z/E = 75:25) of α,β-dialkylvinyl substrates, while a dramatic decrease on enantioselectivity was observed in the case of α-methyl-β-anisylvinyl acetate (Z/E = 58:42). Complementary deuteration reactions are in accord with a highly enantioselective hydrogenation for both olefin isomers in the case of α,β-dialkylvinyl esters. In contrast, deuteration shows a complex behavior for α-methyl-β-anisylvinyl acetate derived from the participation of the E isomer in the reaction.
Highly Stereoselective Synthesis and Hydrogenation of (Z)-1-Alkyl-2-arylvinyl Acetates: A Wide Scope Procedure for the Preparation of Chiral Homobenzylic Esters
González-Liste, Pedro J.,León, Félix,Arribas, Inmaculada,Rubio, Miguel,García-Garrido, Sergio E.,Cadierno, Victorio,Pizzano, Antonio
, p. 3056 - 3060 (2016/07/06)
A synthesis of (Z)-1-alkyl-2-arylvinyl acetates 3 with broad scope is reported by using two complementary methods. The first one uses a stereospecific gold-catalyzed addition of acetic acid to 1-iodo-alkynes, followed by a Suzuki coupling. By the second,
DIRECT ANTI-MARKOVNIKOV ADDITION OF ACIDS TO ALKENES
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Page/Page column 2; 14; 15, (2013/12/03)
A method of making an anti-Markovnikov addition product is carried out by reacting an acid with an alkene or alkyne in a dual catalyst reaction system to the exclusion of oxygen to produce said anti-Markovnikov addition product; the dual catalyst reaction system comprising a single electron oxidation catalyst in combination with a hydrogen atom donor catalyst. Compositions useful for carrying out such methods are also described.
Direct catalytic anti-markovnikov addition of carboxylic acids to alkenes
Perkowski, Andrew J.,Nicewicz, David A.
supporting information, p. 10334 - 10337 (2013/08/23)
A direct catalytic anti-Markovnikov addition of carboxylic acids to alkenes is reported. The catalyst system is comprised of the Fukuzumi acridinium photooxidant (1) and a substoichiometric quantity of a hydrogen-atom donor. Oxidizable olefins, such as styrenes, trisubstituted aliphatic alkenes, and enamides, can be employed along with a variety of carboxylic acids to afford the anti-Markovnikov addition adducts exclusively. A deuterium-labeling experiment lends insight to the potential mechanism.
A new enzymatic approach to (R)-Tamsulosin hydrochloride
Acetti, Daniela,Brenna, Elisabetta,Fuganti, Claudio
, p. 488 - 492 (2007/10/03)
An enantioselective baker's yeast mediated approach to the pharmacologically active (R)-enantiomer of Tamsulosin hydrochloride is reported.
Baker's Yeast-mediated Preparation of Optically Active Aryl Alcohols and Diols for the Synthesis of Chiral Hydroxy Acids
Ferraboschi, Patrizia,Grisenti, Paride,Manzocchi, Ada,Santaniello, Enzo
, p. 2469 - 2474 (2007/10/02)
Baker's yeast reduction of 1-(4-methoxyphenyl)propan-2-one, 4-phenylbutan-2-one, and 2-hydroxy-1-(4-methoxyphenyl)ethanone (p-methoxyphenacyl alcohol), afforded in good yield and high optical purity the corresponding (S)-alcohols and the (R)-diol, but only after careful investigation of incubation conditions.Protection of the above hydroxy compounds, and ruthenium tetraoxide oxidation of their acetates, afforded the corresponding acetoxy acids in good yield and high optical purity. (S)-1-(p-Methoxyphenyl)ethane-1,2-diol could be prepared either by baker's yeast incubation of the acetate of p-methoxyphenacyl alcohol or 2-acetoxy-1-(4-methoxyphenyl)ethanone (24percent yield, 82percent ee) or from its (R)-enantiomer via a Mitsonobu reaction on its mono t-butyldimethylsilyl ether.
