Convenient Synthesis of 4-Methylene-2-oxazolidinones and 4-Methylenetetrahydro-1,3-oxazin-2-ones via Transition-Metal Catalyzed Intramolecular Addition of Nitrogen Atom to Acetylenic Triple Bond
作者:Yoshinao Tamaru、Masanari Kimura、Shuji Tanaka、Sigeru Kure、Zen-ichi Yoshida
DOI:10.1246/bcsj.67.2838
日期:1994.10
2-Propynyl tosylcarbamates 1 undergo cyclization smoothly by the catalysis of CuCl/Et3N or AgNCO/Et3N to furnish 4-methylene-2-oxazolidinones 2 in good yields. The similar cyclization of the N-acyl derivatives of 1 (PhCO, MeCO, EtOCO, etc.) is catalyzed effectively by AgNCO/t-BuOK. These reactions accommodate a variety of substituents at C1 and C3 of 2-propyn-1-ol and provide (Z)-2 as single stereoisomers. The scope of the cyclization of 3-butynyl carbamates is rather limited, and in general only N-tosyl derivatives of terminally unsubstituted 3-butyn-1-ols undergo cyclization to give 4-methylenetetrahydro-1,3-oxazin-2-ones in synthetically useful yields by the catalysis of AgNCO/Et3N or AgNCO/t-BuOK.
Comparison between Conventional and Nonconventional Methods for the Synthesis of Some 2-Oxazolidinone Derivatives and Preliminary Investigation of Their Inhibitory Activity Against Certain Protein Kinases
作者:S. Ziane、M. M. Mazari、A. M. Safer、A. Sad El Hachemi Amar、S. Ruchaud、B. Baratte、S. Bach
DOI:10.1134/s1070428019070248
日期:2019.7
A series of propargyl and allyl carbamates were prepared directly from propargyl and allyl alcohols and phenyl or cyclohexyl isocyanate or indirectly by generating the isocyanates in situ from the corresponding Cbz-protected amines. The obtained carbamates underwent intramolecular nucleophilic cyclization in presence of cesium hydroxide monohydrate as a base catalyst under conventional and ultrasonic
The base catalyzed cyclization of N-aryl and N-alkyl-O-propargyl carbamates is studied in detail. The effect of various bases and solvents on the efficacy of this cyclization reaction is analyzed and a new base–solvent system (LiOH in DMF) for effective cyclization of these carbamates is reported. A number of differentially substituted O-propargyl carbamates were cyclized to the corresponding 2-oxazolidinones
A new lipase, Ndbn, capable of efficiently catalyzing the amidation between esters and aromatic amines which are weak nucleophilic reagents was discovered. Furthermore, Ndbn exhibits the capability to catalyze the aminolysis of carboxylic acids without the need for preparing ester substrate or a strictly anhydrous reaction environment. Additionally, an unusual preference of Ndbn for aromatic amines
作者:S. Yu. Vyazmin、S. E. Berezina、L. A. Remizova、I. N. Domnin、R. Gleiter
DOI:10.1023/a:1020326818084
日期:——
Carbamates of monoacetylene and diacetylene series were synthesized and characterized. A catalytic system CuI-pyrrolidine was applied for the first time to a synthesis of symmetrical diacetylenes by oxidative dimerization of terminal acetylenes. The comparative activity of diynes obtained was studied in the photoinitiated solid-phase topochemical polymerization. Diyne carbamates undergoing thermal polymerization were obtained for the first time.