Rearrangements of azidoquinones. VIII. Photolytic rearrangement of 2,5-diazido-1,4-benzoquinones to 2-cyano-4-azido-1,3-cyclopentenediones, precursors to cyanoketenes
2-Trimethylsilythiazole (2) and 2,5-bis(tri-methylsilyl) thiazole (6) undergo ipso-substitution of the 2-SiMe3 group with various ketens affording the thiazolyl-trimethylsiloxy-ethylenes (3) and(7), respectively, which are hydrolysed to the 2-acylthiazoles (4), whereas 5-trimethylsilylthiazole (8) undergoes attack at C-2 by dichloroketen giving the Michael-type adduct 2-dichloro-acetyl-5-trimethylsilylthiazole
Addition reactions of tert-butylcyanoketene to silyl enol ethers and conjugated dienes.
作者:Abdulrahman H. AI-Husaini、Ikhtiar Khan、Sk.Asrof Ali
DOI:10.1016/s0040-4020(01)80908-x
日期:——
A study of the addition reactions of tert-butylcyanoketene with several 1-aryl-1-trimethylsiloxy ethenes and acyclic conjugateddienes has been carried out. These reactions are suggested to proceed by stepwise pathways involving zwitterionic intermediates.
Thermal isomerisation of adducts derived from t-butylcyanoketen and allenes
作者:Howard A. Bampfield、Peter R. Brook
DOI:10.1039/c39740000172
日期:——
The intervention of a zwitterionic intermediate is proposed in the thermalisomerisations of the t-butyl-cyanoketen-methylated allene adducts (6) and (8), but not for adducts (1)–(4); evidence is given for the intervention of a similar intermediate in the cycloaddition of t-butylcyanoketen to 1-t-butyl-1-methylallene.
Reaction of 3,3-dimethyl- and 1,3,3-trimethylcyclopropene with t-butylcyanoketen. Formation of bicyclo[2,1,0]pentan-2-ones
作者:Donald H. Aue、Dale F. Shellhamer、Gregory S. Helwig
DOI:10.1039/c39750000603
日期:——
Addition of t-butylcyanoketen to 3,3-dimethylcyclopropene and 1,3,3-trimethylcyclopropene gives mixtures of the bicyclo[2,1,0]pentan-2-ones (3a,b) and rearranged products (4a,b) and (5b); the ketone (3b) rearranges to (6b) but not to (4b).
Electrophilic reagents attack the phosphatriafulvenes 1a and 1b exclusively at the phosphorus atom. Hence 1b is methylated by methyl iodide to furnish the cyclopropenylium iodide 3 which, in turn, is converted to the triazine 6 by reaction with sodium azide. Ketenes 8 react with 1a through subsequent P → O silyl shifts to give the vinylphosphatriafulvenes 10. Isocyanates 13a and 13b behave analogously (→ 15). In the reactions of 1a with isothiocyanates 13c and 13d, in contrast, a P → N silyl shift is observed which leads to the formation of 16. Acetylenedicarboxylates 17 undergo insertion into the P/Si bond of the silylated phosphatriafulvene 1a (→ 19). In the case of the reaction of the mesitylsubstituted phosphatriafulvene 1b with 17, kinetically controlled formation of the dihydrooxophosphinines 20 takes place; at room temperature, the latter products undergo slow rearrangement to give the thermodynamically more stable isomers 21.