78347-42-9Relevant academic research and scientific papers
Regioselective Halo- and Carbodesilylation of (Trimethylsilyl)-1-methylpyrazoles
Effenberger, Franz,Krebs, Andreas
, p. 4687 - 4695 (2007/10/02)
The isomeric 3-, 4-, and 5-(trimethylsilyl)- as well as the 3,4-, 3,5-, and 4,5-bis(trimethylsilyl)-1-methylpyrazoles (2, 7, 3, 5, 9, and 10, respectively) are obtained by methylation of the corresponding (trimethylsilyl)-1H-pyrazoles or by silylation of Grignard or lithio derivatives of appropriate 1-methylpyrazoles with chlorotrimethylsilane. 5 and 10 are halodesilylated regioselectively by Br2 or ICl in the 4-position, yielding 13 and 15.With addditional bromine, these monobromo compounds suffer exclusively bromodesilylation to give 3,4- and 4,5-dibromo-1-methylpyrazole (14 and 16, respectively).These findings are in accord with the electrophilic substitution reactivity indices for 1-methylpyrazole (8) and with ipso-directing influence of the Me3Si group.The reaction of 5 with I2, unexpectedly, attacks preferentially at the 3-position.Regioselective carbodesilylation in the 5-position is observed in the fluoride-catalyzed reactions of 3, 9, and 10 with carbon electrophiles.The high regiospecificity of this reaction is rationalized in terms of carbanion stabilization at the individual pyrazole positions.
ETUDE DANS LA SERIE DES ORGANOSILYLAZOLES. II. REACTION D'ADDITION NUCLEOPHILE SUR LES DERIVES CARBONYLES
Gasparini, J.P.,Gassend, R.,Maire, J.C.,Elguero, J.
, p. 309 - 315 (2007/10/02)
The reactivity of organosilicon amines of imidazole, 1,2,4-triazole and benzotriazole towards aldehydes and ketones has been studied.Aldehydes react easily and give the addition products at room temperature.With ketones, the reactions depend both on the organosilicon amine and the ketone used.With trimethylsilyl-1 imidazole, ketones having an enolic form stabilized by conjugation, form enoxysilanes.
