- Product Selectivity in KAHA Ligations: Ester vsAmide Formation with Cyclic Hydroxylamines
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Cyclic hydroxylamines form esters instead of the expected amides as major product upon reaction with α-ketoacids. In this report, we document a systematic investigation into the effect of the hydroxylamine structure and the solvent mixture on the product
- Rohrbacher, Florian,Baldauf, Simon,Wucherpfennig, Thomas G.,Bode, Jeffrey W.
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supporting information
p. 1929 - 1933
(2017/09/13)
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- Novel process
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A process for the preparation of a 4-aryl-3-oxymethyl-piperidine of structure (1) in which R is hydrogen or an alkyl, arylalkyl, allyl, acyl, carbonyloxyalkyl, carbonyloxyaryl, or carbonyloxyalkylaryl group, and Y is a hydrogen atom or an optionally substituted alkyl, arylalkyl, or aryl group, from a carboxy derivative of structure (2) where A is oxygen or sulphar, X is one or more of hydrogen, or a readily reducible group, Z represents either a hydrogen atom or an OY′ group in which Y′ is independently selected from the same groups as Y, and the broken line circle indicates bonding, appropriate to a tetrahydropyridine, dihydropyridine, pyridine, or piperidine ring said process comprising (a) when Y is a hydrogen atom, reducing the compound of structure (2), or (b) when Y is other than a hydrogen atom (i) forming an ether from the alcohol product of step (a), (ii) etherifying the aldehyde compound of structure (2) in which Z is hydrogen, or (iii) reducing the ester compound of structure (2) in which Z is OY′.
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- Process for preparing pharmaceutically active compounds and intermediates thereof
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A process is disclosed for the preparation of (1) by reduction of (2) directly using catalytic transfer hydrogenation to suppress formation of (4) or by conventional reduction via (4). Compound (1) is a key intermediate for inter alia paroxetine.
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- 3-substitutes isoxazolidines as chiral auxiliary agents
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Disclosed are compounds of the formula: where R is selected from the group consisting of C1-C4 linear or branched alkyl, trifluoromethyl, halo, phenyl, biphenyl and naphthyl, wherein the aromatic group can be substituted with C1-C4 linear or branched alkyl, trifluoromethyl, or halo; and wherein the asterisked 3-position ring carbon is either in (R) or (S) configuration, or racemate form, and salts thereof formula I. The compounds are useful in chiral synthesis, for example, producing naturally occurring L-amino acids, e.g., alanine, from aliphatic acid precursors.
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- Method of preparing optically active alpha -amino acids and alpha -amino acid derivatives
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PCT No. PCT/EP96/03984 Sec. 371 Date Apr. 30, 1998 Sec. 102(e) Date Apr. 30, 1998 PCT Filed Sep. 11, 1996 PCT Pub. No. WO97/10203 PCT Pub. Date Mar. 20, 1997The invention relates to a new process for the preparation of optically active amino acids and amino acid derivatives of the general formula (I), wherein *, X and R1 to R4 have the meaning given in the description. Starting from commercially obtainable (-)-menthol or (+)-menthol, the enantiomerically pure compounds of the formula (I) are obtained in high yields. The method is particularly suitable for the preparation of sterically demanding amino acids and amino acid derivatives.
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- Binder combinations, a process for their preparation and their use
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Compositions useful as a binder in lacquers and coating compositions and which are curable by moisture contain: (A) from 30 to 99 parts by weight of at least one copolymer of olefinically unsaturated compounds having a weight average molecular weight of from 1500 to 75,000 and containing chemically incorporated moieties capable of undergoing an addition reaction with amino groups, and (B) from 1 to 70 parts by weight of at least one organic polyamine containing blocked amino groups, wherein (i) the copolymers of component (A) contain both intramolecular carboxylic acid anhydride moieties and epoxide moieties in a chemically bound form, with the anhydride equivalent weight of the copolymers being from 393 to 9,800 and the epoxide equivalent weight of the copolymers from 568 to 14,200, and (ii) the binder composition contains from 0.2 to 8 anhydride and epoxide moieties for each blocked amino group.
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