Reference

Heterogeneous Asymmetric Reactions 20

Heterogeneous Asymmetric Reactions 20. Effect of Ultrasonic Variables on the Enantiodifferentiation in Cinchona-Modified Platinum-Catalyzed Sonochemical Hydrogenations. Toeroek, Bela; Balazsik, Katalin; Toeroek, Marianna; Felfoeldi, Karoly; Bartok, Mihaly (Organic Catalysis Research Group of the Hungarian Academy of Sciences, University of Szeged, Szeged H-6720, Hung.). Catalysis Letters, 81(1-2), 55-62 (English) 2002 Kluwer Academic/Plenum Publishers. CODEN: CALEER. ISSN: 1011-372X. DOCUMENT TYPE: Journal CA Section: 22 (Physical Organic Chemistry) The effect of sonochem. variables on a cinchona alkaloid modified Pt/Al2O3 catalyst system and its application in a-keto ester hydrogenation are described. The sonochem. pretreatment of these com. Pt/Al2O3-cinchonidine catalysts resulted in excellent ee values (up to 92-98 ee) under mild exptl. conditions. To gain more insight into the nature of the ultrasonic effect the reactions were screened under widely varied conditions (ultrasound source, frequency, insonation time). Besides studying the reactions, the catalyst-modifier system was also studied. The changes in metal particle size were detd. by TEM, while the alteration of modifier concn.There are some commonly used reagents with their cas registry numbers 64920-29-2 and 486459-17-0 in this article. in the solvent upon sonication was followed by UV-visible spectroscopy. The transformation of the modifier during the pretreatment was detected by GC-MS and verified by NMR. Summarizing the results, the major effects of the sonochem. activation on the cinchona-modified supported Pt catalyst system can be described. The ultrasonic pretreatment increased the quantity of adsorbed cinchona and blocked its hydrogenation to provide more and highly stable chiral active sites for enantioselection. .

Angiotensin-converting enzyme inhibiting dipeptide derivatives

Angiotensin-converting enzyme inhibiting dipeptide derivatives.Some chemicals with cas registry numbers like 106014-34-0 are also used. Martin, Tellis A.; Dolak, Terence M. (Mead Johnson and Co., USA). U.S. US 4617291 A 14 Oct 1986, 6 pp. (United States of America) CODEN: USXXAM. CLASS: ICM: A61K037-43. ICS: C07K005-06; C07C101-44. NCL: 514019000. APPLICATION: US 82-378295 14 May 1982. DOCUMENT TYPE: Patent CA Section: 1 (Pharmacology) Section cross-reference(s): 34 The title compds. I (A = H, halo, alkyl, alkoxy; B = H, alkyl; AB = o-methylene, o-ethylene; R = H, alkyl, phenylalkyl; X1, X2 = OH, alkoxy) are prepd. as angiotensin-converting enzyme inhibitors (no data). Reductive condensation of tert-Bu N-(S)-alanyl-N-phenylglycinate (prepn. given) with Et 2-oxo-4-phenylbutyrate (prepn. given) over Pd/C, in hexane-EtOAc (2:1) gave (S,S)-N-[1-(ethoxycarbonyl)-3-phenylpropyl]alanyl-N-phenylglycine. .