Silylenoids are species containing an alkali metal (M) and a leaving group (X, usually halogen) bound to the same silicon atom, which makes them display amphiphilic properties. Reaction of a silylenoid with a compound containing a CN double bond has not been studied, whereas considerable experimental studies have been reported by several groups in case of silylenes which shared reaction characteristics with silylenoids. Herein, we report on reactions of a silylenoid with imines, such as N-butylphenylimine, N,1-di(phenyl)methanimine, which can be a new synthetic method for the synthesis of N, Si-containing heterocyclic compounds.
Bromosilylenoid, 2 was prepared from the reaction of tribromo[tris(trimethylsilyl)methyl]silane, 1 with two equivalents of lithium naphthalenide in THF at -78 °C. Then, imines were added to resulting solution at same temperature. Interestingly, there was a great difference on results of reactions depending on imines. In case of reaction of 2 with N-butylphenylimine at -50 °C for 12 h, azaindane, 3 was synthesized through rearrangement in 45% yield. Compound 3 was characterized by multinuclear NMR spectroscopy and X-ray structural analysis. On the other hand, silaaziridine, 4 was synthesized from the reaction of 2 with N,1-di(phenyl)methanimine at -50 °C for 6 h, which was characterized by 29Si NMR spectroscopy. Ring cleavage of 4 was occurred by MeOH to give α-silyl amine 5 in 67% yield. Compound 5 was characterized by GC/MS and multinuclear NMR spectroscopy.
In this presentation, we will discuss the chemistry of bromosilylenoid with imines in detail.