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Cyano Ketones (cyano + ketone)
Selected AbstractsHighly Enantioselective Michael Addition of ,-Substituted Cyano Ketones to ,,,-Unsaturated ,-Keto Esters using Bifunctional Thiourea-Tertiary Amine Catalysts: An Easy Access to Chiral DihydropyransADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2009Sheng-Li Zhao Abstract An asymmetric Michael addition of ,-substituted cyano ketones to ,,,-unsaturated ,-keto esters to form chiral dihydropyrans catalyzed by a series of ,-amino acid-derived thiourea-tertiary amines is presented. A novel tyrosine-derived thiourea catalyst was identified as the optimal catalyst providing the desired product in 91,95% yields and with 90,96% ee at a low catalyst loading of 2.0,mol%. The utility of the reaction was exemplified by facile conversion of the dihydropyran product into pharmaceutically useful dihydropyridine. [source] Enantio- and Diastereoselective Mannich-Type Reactions of ,-Cyano Ketones with N -Boc Aldimines Catalyzed by Chiral Bifunctional UreaADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2009Ju Hee Lee Abstract The catalytic enantioselective electrophilic Mannich-type reaction promoted by chiral bifunctional organocatalysts is described. The treatment of ,-cyano ketones with N -Boc-aldimines under mild reaction conditions afforded the corresponding ,-amino-,-cyano ketones with excellent diastereoselectivities (up to syn/anti=100/0), and excellent enantioselectivities (up to 99% ee). [source] Lithium Naphthalenide-Induced Reductive Selenenylation of ,-Cyano Ketones: A Regiocontrolled Process for ,-Phenylseleno Ketones and One-Pot Conversion into Enone System.CHEMINFORM, Issue 38 2007Jia-Liang Zhu Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Val-Ala Dipeptide Isosteres by Hydrocyanation of ,,-Amino ,,,-Unsaturated Ketones , Control of Stereoselectivity by the N -Protecting GroupEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2003Fabio Benedetti Abstract Three diastereoisomeric hydroxyethylene isosters of the Val-Ala dipeptide were synthesized from ,,,-unsaturated ketones 1 derived from N -Boc- and N,N -dibenzyl- L -valine. The enones were hydrocyanated with diethylaluminum cyanide to give the corresponding ,-cyano ketones with the stereoselectivity depending on the protecting group. N -Boc protected enone 1a gave a 1:1 mixture of anti and syn adducts 4a, 5a while the corresponding N,N -dibenzyl compound 1c gave a 6:1 mixture of anti, syn adducts 4c, 5c. Borohydride reduction of the resulting cyano ketones is also controlled by the protecting group, resulting in opposite stereoselectivities for N -Boc and N,N -dibenzyl compounds. The cyano alcohols thus obtained were converted, in several steps, into two series of enantiomerically pure hydroxyethylene isosters of the Val-Ala dipeptide. In the first series the hydroxy group and the N -terminal of the isoster are internally protected through the formation of an oxazolidine; in the second series the hydroxy group and the C-terminal are protected as lactone. Two oxazolidines (28, 29), corresponding to syn,syn and syn,anti 4-hydroxy-5-amino acid isosters, and three lactones (23,25), corresponding to syn,syn, syn,anti, and anti,anti isosters were obtained by this approach. (© Wiley-VCH Verlag GmbH & Co KGaA, 69451 Weinheim, Germany, 2003) [source] Highly Enantioselective Michael Addition of ,-Substituted Cyano Ketones to ,,,-Unsaturated ,-Keto Esters using Bifunctional Thiourea-Tertiary Amine Catalysts: An Easy Access to Chiral DihydropyransADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2009Sheng-Li Zhao Abstract An asymmetric Michael addition of ,-substituted cyano ketones to ,,,-unsaturated ,-keto esters to form chiral dihydropyrans catalyzed by a series of ,-amino acid-derived thiourea-tertiary amines is presented. A novel tyrosine-derived thiourea catalyst was identified as the optimal catalyst providing the desired product in 91,95% yields and with 90,96% ee at a low catalyst loading of 2.0,mol%. The utility of the reaction was exemplified by facile conversion of the dihydropyran product into pharmaceutically useful dihydropyridine. [source] Enantio- and Diastereoselective Mannich-Type Reactions of ,-Cyano Ketones with N -Boc Aldimines Catalyzed by Chiral Bifunctional UreaADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2009Ju Hee Lee Abstract The catalytic enantioselective electrophilic Mannich-type reaction promoted by chiral bifunctional organocatalysts is described. The treatment of ,-cyano ketones with N -Boc-aldimines under mild reaction conditions afforded the corresponding ,-amino-,-cyano ketones with excellent diastereoselectivities (up to syn/anti=100/0), and excellent enantioselectivities (up to 99% ee). [source] | ||||||||||