Gas-phase kinetics of elimination reactions of pentane-2,4-dione derivatives. Part ii [1]. Thermolysis of derivatives and analogues of 3-phenylhydrazonopentane-2,4-dione
摘要:
Six analogues and derivatives (1-6) of 3-phenylhydrazonopentane-2.4-dione (7) were subjected to gas-phase thermolysis. The Arrhenius log A (s(-1)) and Ea (kJ mol(-1)) of the analogues (1-5) are, respectively: 10.42 and 140.8 for 1-cyano-1-phenyl-hydrazonopropanone (1), 11.19 and 135.4 for 1-cyano-1-(p-nitrophenylhydrazono)-propanone (2), 10.68 and 144.9 for l-cyano-1-(p-methoxyphenylhydrazono)propanone (3), 11.76 and 137.8 for 1-cyano-3-phenyl-1-phenylhydrazonopropanone (4), and 11.29 and 145.9 for 1-cyano-1-phenylhydrazonobutanone (5). The corresponding values for ethyl 3-oxo-2-phenylhydrazonobutanoate (6) are 11.90 s(-1) and 141.3 kJ mol(-1). The rates of reaction at 600 K are compared with those of the title diketone (7) and of pentane-2,4-dione (8) and rationalized in terms of a plausible elimination pathway involving a semiconcerted six-membered transition state. (C) 1998 John Wiley & Sons, Inc.
An Unusual Rearrangement of Pyrazole Nitrene and Coarctate Ring-Opening/Recyclization Cascade: Formal CH–Acetoxylation and Azide/Amine Conversion without External Oxidants and Reductants
作者:Elena Chugunova、Almir S. Gazizov、Daut Islamov、Victoria Matveeva、Alexander Burilov、Nurgali Akylbekov、Alexey Dobrynin、Rakhmetulla Zhapparbergenov、Nurbol Appazov、Beauty K. Chabuka、Kimberley Christopher、Daria I. Tonkoglazova、Igor V. Alabugin
DOI:10.3390/molecules28217335
日期:——
of a nitrene moiety initiates a sequence of steps leading to remote oxidative C–H functionalization (R–CH3 to R–CH2OC(O)R’) and the concomitant reduction of the nitrene into an amino group. No external oxidants or reductants are needed for this formal molecular comproportionation. Detected and isolated intermediates and computational analysis suggest that the process occurs with pyrazole ring opening