Home About us Contact
|
Home About us Contact | ||
|
|
||
Lactam Formation (lactam + formation)
Selected AbstractsMicrowave-Induced Stereocontrol of , -Lactam Formation with an N -Benzylidene-9,10-dihydrophenanthren-3-amine via Staudinger CycloadditionHELVETICA CHIMICA ACTA, Issue 2 2010Debasish Bandyopadhyay Abstract The synthesis of 3-substituted 4-phenyl-1-(9,10-dihydrophenanthren-3-yl)azetidin-2-ones was achieved following Staudinger cycloaddition under microwave-induced conditions. The stereoselectivity of , -lactam formation depended on the power level of the microwave irradiation used in the experiments. [source] ChemInform Abstract: Enantioselective, NHC-Catalyzed Bicyclo-,-lactam Formation via Direct Annulations of Enals and Unsaturated N-Sulfonyl Ketimines.CHEMINFORM, Issue 22 2008Ming He 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 of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Microwave-Induced Stereocontrol of , -Lactam Formation with an N -Benzylidene-9,10-dihydrophenanthren-3-amine via Staudinger CycloadditionHELVETICA CHIMICA ACTA, Issue 2 2010Debasish Bandyopadhyay Abstract The synthesis of 3-substituted 4-phenyl-1-(9,10-dihydrophenanthren-3-yl)azetidin-2-ones was achieved following Staudinger cycloaddition under microwave-induced conditions. The stereoselectivity of , -lactam formation depended on the power level of the microwave irradiation used in the experiments. [source] Amide and lactam hydrolysis of N -(2-hydroxyacetyl)-2-pyrrolidone: effective catalysis,JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 11 2006Lisaedy García Borboa Abstract When N -(2-hydroxyacetyl)-2-pyrrolidone (open form) is dissolved in water at pH,>,8, irreversible cleavage of the exocyclic and endocyclic amide CN bond occurs. The latter rupture corresponds to the lactam opening yielding N -(4-hydroxyacetyl)butanoic acid (NBA). NBA is produced from the ester hydrolysis of the ester-amide macrocycle that is in equilibrium with the cyclol form of the open form. We have previously reported this latter equilibrium for N -(2-aminoacetyl)-2-lactams. 2-pyrrolidone (lactam) and glycolic acid are produced from direct hydrolysis of the open form by means of the amide exocyclic cleavage. The [NBA]/[lactam] ratio increases at higher pH since the NBA production is second order with respect to [OH,] while the corresponding lactam formation is only first order. The obtained kobs is hence the sum of the rate constants that yield lactam and NBA, respectively. This kobs is uncatalyzed and specific base catalyzed with unusually high rate constants of 2.1,×,10,6,s,1 and 0.025,M,1,s,1, respectively. The stability of the corresponding tetrahedral intermediate formed and the intramolecular alkoxy nucleophilic attack on the lactam carbonyl group combined with an effective protonation of the lactam nitrogen that promotes the CN cleavage, contribute to increase the reaction rates and lactam opening. Rate constants for the two parallel reactions are obtained from kobs and [NBA]/[lactam] versus pH plots. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||