- Enantioselective Synthesis of α-Allyl Amino Esters via Hydrogen-Bond-Donor Catalysis
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We report a chiral-squaramide-catalyzed enantio- and diastereoselective synthesis of α-allyl amino esters. The optimized protocol provides access to N-carbamoyl-protected amino esters via nucleophilic allylation of readily accessible α-chloro glycinates. A variety of useful α-allyl amino esters were prepared, including crotylated products bearing vicinal stereocenters that are inaccessible through enolate alkylation, with high enantioselectivity (up to 97% ee) and diastereoselectivity (>10:1). The reactions display first-order kinetic dependence on both the α-chloro glycinate and the nucleophile, consistent with rate-limiting C-C bond formation. Computational analysis of the uncatalyzed reaction predicts an energetically inaccessible iminium intermediate, and a lower energy concerted SN2 mechanism.
- Bendelsmith, Andrew J.,Kim, Seohyun Chris,Wasa, Masayuki,Roche, Stéphane P.,Jacobsen, Eric N.
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supporting information
p. 11414 - 11419
(2019/08/20)
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- PREPARATION OF OPTICALLY PURE BETA-AMINO ACIDS HAVING AFFINITY FOR THE ALPHA-2-DELTA PROTEIN
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Disclosed are materials and methods for preparing optically active β-amino acids, which bind to the alpha-2-delta subunit of a calcium channel and are useful for treating pain, fibromyalgia, and a variety of psychiatric and sleep disorders. The method includes reacting a chiral allyl amine with a 2-alkynoate in the presence of a Lewis acid and a base to give a chiral tertiary enamine, which after reaction with ammonia, is hydrogenated to give optically active β-amino acids.
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Page/Page column 52-53
(2008/06/13)
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- Regio- and Stereoselective Substitution of Hydroxy Group in Allyl Alcohols by Halogen
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A preparative method for regio- and stereoselective substitution of the hydroxy group by halogen in allyl alcohols under the action of triphenylphosphine complexes with ethyl trichloroacetate or trichloroacetonitrile has been developed.The regio- and stereoselectivity of substitution of hydroxy group by halogen with triphenylphosphine complexes and compounds containing trichloromethyl group is compared.
- Matveeva, E. D.,Erin, A. S.,Mitroshin, D. B.,Kurts, A. L.
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p. 1019 - 1022
(2007/10/03)
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- Surface Catalyzed Hydrochlorination of 1,3-Butadiene
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The rates of disappearance of gaseous hydrogen chloride (-d/dt) and 1,3-butadiene and appearance of the gaseous products 3-chloro-1-butene and (E)- and (Z)-1-chloro-2-butene (+d/dt) in Pyrex IR cells at 295 K and total initial pressures of about 450 torr are found to be proportional to the surface-to-volume ratio (S/V) of the reaction vessel.
- Mascavage, Linda M.,Dalton, David R.
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p. 3461 - 3464
(2007/10/02)
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- Surface-Catalyzed Hydrochlorination of Alkenes. The Reaction of the Gases Hydrogen Chloride and 1,3-Butadiene
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Mixtures of gaseous hydrogen chloride and gaseous 1,3-butadiene at total pressures less than 1 atm and at temperatures between 294 and 334 K yield mixtures of 3-chloro-1-butene and (E)- and (Z)-1-chloro-2-butene.The ratio of the product of putative 1,2-addition to those of 1,4-addition is approximately unity with only the amount of (Z)-1-chloro-2-butene increasing from ca. 2percent of the total reaction product mixture at the lower temperature to ca. 4percent at the higher temperature.Kinetic measurements have been made by observing the reaction throughout its course utilizing FT-IR spectroscopy.It is concluded that surface catalysis is required for product formation and that the reaction, which occurs at the walls, is most probably between multilayer adsorbed hydrogen chloride and gaseous or weakly adsorbed 1,3-butadiene.
- Mascavage, Linda M.,Chi, Hongji,La, Sangmoo,Dalton, David R.
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p. 595 - 601
(2007/10/02)
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- TOTAL STEREOSPECIFICITY IN FREE RADICAL INTRAMOLECULAR ADDITION: CYCLISATION OF CIS AND TRANS 1-METHYL 4-HEXENYL N-CHLOROAMINES BY MEANS OF METALLIC SALTS
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Extremely high stereospecificity (up to 100percent diastereoisomeric purity) can be obtained for the metallic salts induced radical cyclisation of the cis and trans 1-methyl 4-hexenyl N-chloroamines.A possible mechanism for the highly effective trans-addition using metal-complexed aminyl radical is proposed.
- Bougeois, Jean-Luc,Stella, Lucien,Surzur, Jean-Marie
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