An efficient and high yielding Cu-catalyzed direct CâH arylation of azaheterocycles including oxadiazoles, thiadiazoles, benzoxazoles and benzothiazoles has been achieved by employing easily accessible diaryliodonium salts.
A practical and transition-metal-freeoxidative cyclization of acylhydrazones into 1,3,4-oxadiazoles has been developed by employing stoichiometric molecular iodine in the presence of potassium carbonate. The conditions of this cyclization reaction also work well with crude acylhydrazone substrates obtained from the condensation of aldehydes and hydrazides. A series of symmetrical and asymmetrical
Synthesis of mesityl-substituted 1,3,4-oxadiazoles from mesitotrichloride and aromatic and heteroaromatic acid hydrazides
作者:L. I. Belen'kii、S. I. Luiksaar、M. M. Krayushkin
DOI:10.1007/bf02319340
日期:1999.4
Spectral luminescent properties of 2-aryl-5-(2,4,6-trimethylphenyl)-1Н-1,3,4-oxadiazoles
作者:Yu. M. Artyushkina、I. E. Mikhailov、G. A. Dushenko、O. I. Mikhailova、Yu. V. Revinskii、O. N. Burov、S. V. Kurbatov
DOI:10.1134/s1070428017050281
日期:2017.5
Reaction of aroylhydrazides with 2,4,6-trimethylbenzoyl chloride in the presence of Et3N afforded N-(mesityl)aroylhydrazides, which through subsequent cyclization at treatment with SOCl2 resulted in 2-aryl-5-(2,4,6-trimethylphenyl)-1De-1,3,4-oxadiazoles. For 2-hydroxyphenyl derivative containing a stable O-H N intramolecular bond a low quantum luminescence yield is observed (phi 0.006-0.038) due to the nonradiative deactivation of the agitated state by ESPIT mechanism.
Steric Effects on the Regioselectivity in Two-Step Diels–Alder Reactions of 1,2,4,5-Tetrazines with 2-Cyclopropylidene-4,5-dihydro-1,3-dimethyl-imidazolidine
作者:Klaus-Peter Hartmann、Manfred Heuschmann
DOI:10.1016/s0040-4020(00)00346-x
日期:2000.6
The regioselectivity of the two-stepDiels–Alderreaction of unsymmetrically substituted tetrazines 4 with 2-cyclopropylidene-imidazolidine 6 is investigated. The first reversible step of the cycloaddition affording zwitterions 7 and 8 is controlled by steric effects, which are explained using a simple model. The overall regioselectivity, however, is determined in the second step of the cycloaddition