60633-83-2Relevant academic research and scientific papers
Chiral syntheses of methyl (R)-2-Sulfanylcarboxylic esters and acids with optical purity determination using HPLC
Sasaki, Ryosuke,Tanabe, Yoo
, p. 816 - 827 (2018/04/30)
Accessible chiral syntheses of 3 types of (R)-2-sulfanylcarboxylic esters and acids were performed: (R)-2-sulfanylpropanoic (thiolactic) ester (53%, 98%ee) and acid (39%, 96%ee), (R)-2-sulfanylsucciinic diester (59%, 96%ee), and (R)-2-mandelic ester (78%, 90%ee) and acid (59%, 96%ee). The present practical and robust method involves (i) clean SN2 displacement of methanesulfonates of (S)-2-hydroxyesters by using commercially available AcSK with tris(2-[2-methoxyethoxy])ethylamine and (ii) sufficiently mild deacetylation. The optical purity was determined by the corresponding (2R,5R)-trans-thiazolidin-4-one and (2S,5R)-cis-thiazolidin-4-one derivatives based on accurate high-performance liquid chromatography analysis with high-resolution efficiency. Compared with the reported method utilizing AcSCs (generated from AcSH and CsCO3), the present method has several advantages, that is, the use of odorless AcCOSK reagent, reasonable reaction velocity, isolation procedure, and accurate, reliable optical purity determination. The use of accessible AcSK has advantages because of easy-to-handle odorless and hygroscopic solid that can be used in a bench-top procedure. The Ti(OiPr)4 catalyst promoted smooth trans-cyclo-condensation to afford (2R,5R)-trans-thiazolidin-4-one formation of (R)-2-sulfanylcarboxylic esters with available N-(benzylidene)methylamine under neutral conditions without any racemization, whereas (2S,5R)-cis-thiazollidin-4-ones were obtained via cis-cyclo-condensation and no catalysts. Direct high-performance liquid chromatography analysis of methyl (R)-mandelate was also performed; however, the resolution efficiency was inferior to that of the thaizolidin-4-one derivatizations.
Synthesis of optically active α-(nonafluoro-tert-butoxy)carboxylic acids
Csóka, Tamás,Nemes, Anikó,Szabó, Dénes
, p. 1730 - 1733 (2013/04/10)
Three novel α-(nonafluoro-tert-butoxy)carboxylic esters were synthesized by two methods: the Mitsunobu reaction of optically active (S)-α-hydroxycarboxylic esters and the Williamson synthesis starting from the corresponding O-mesyl derivatives. Both procedures from ethyl (S)-lactate resulted in the formation of a fluorous optically active (R)-lactic acid ester derivative, while the reactions from methyl (S)-mandelate took place with racemization. The proposed mechanism of this racemization is described. The conversion of methyl (S)-phenyllactate under Mitsunobu conditions was also stereospecific, but the reaction of its O-mesyl derivative yielded a mixture of substitution and elimination products. The optical purity of the α-(nonafluoro-tert-butoxy)carboxylic acids prepared by the hydrolysis of the above esters was determined by 1H NMR spectroscopy.
ALKALOID AMINOESTER DERIVATIVES AND MEDICINAL COMPOSITION THEREOF
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Page/Page column 53-54, (2010/07/09)
The present invention relates to alkaloid aminoester derivatives acting as muscarinic receptor antagonists, to methods of preparing such derivatives, to compositions comprising them and therapeutic use thereof.
Stereospecific oxygen rearrangement in the reduction of optically pure methyl mandelate to phenylethanol isomers
Angelis,Smonou
, p. 488 - 490 (2007/10/03)
The reduction of methyl (S)-(+)-mandelate, 1, produces the expected 2-phenylethanol, 3, and the unexpected optically pure 1-phenylethanol, 6, by a stereospecific oxygen atom metathesis; which occurs through a styrene oxide intermediate, whose concentration varies with solvent polarity.
