Aminomethyl silane

Keywords lithiumorganyle, (aminomethyl)silane, (lithiomethyl)silane, stereogenic center... 

Summary Our research on a-metalated organosilanes currently focuses on (aminomethyl)silanes containii a defined stereogenic center next to the silicon center. A synthetic route based on the preparation of 2-silyl-substituted pyrrolidines was developed. The racemic product could be synthesized by metalation of JV-Boc-pyrrolidine in the presence of TMEDA and conversion with the corresponding chlorosilane, whereas the enantioenriched form was achieved by metalation in the presence of the chiral amine (-)-sparteine. Subsequent metalation and transformation reactions yielded the formation of the corresponding (aminomethyl)(lithiomethyl)silane. 

According to the the work of P. Beak and coworkers on 2-substituted pyrrolidines [2], the following synthetic route, containing asymmetric deprotonation and transformation of the protecting group, was chosen for the preparation of the (aminomethyl)silanes 3 and 5. The (aminomethyl)(lithiomethyl)silane 4, a molecule of type E (Scheme 1), was achieved by subsequent metalation of 3 (Scheme 2). 

Scheme 2. Preparation of the (aminomethyl)silanes 3 and S and of (aminomethylXlitliioinetbyi)silaAe 4.

As a result of the numerous possibilities for modification at both the nitrogen and the silicon centers, this class of (aminomethyl)silanes has considerable potential for use in synthesis of pharmaceutically interesting compounds [11]. The metalated species can be used as reagents for the transfer of stereogenic centers [la] as well as building blocks for novel ligands of organometallic systems [12]. 

New Organosilicon Reagents Synthesis, Structure, and Reactivity of (Lithiomethyl)(aminomethyl)silanes... 

Summary (Aminomethyl)silanes have been prepared by new synthetic routes starting from lithiosilanes or (lithiomethyl)amines. (Lithiomethyl)(aminomethyl)silanes were formed by metallation with lithioalkyls. A sulfur-substituted (lithiomethyl)(aminomethyl)silane and a THF adduct are characterized by single crystal X-ray diffraction. In reactions of (lithiomethyl)(aminomethyl)silanes with aldehydes or ketones no clear addition/depro-tonation profile was observed. 

Unaware of the above mentioned work we explored, almost at the same time, the similar theme and encountered some very interesting and novel findings about the synthesis and structure of (lithiomethyl)(aminomethyl)silanes. We are presenting new synthetic routes to (aminomethyl)silanes and (lithiomethyl)(aminomethyl)silanes and we want to give experimental information on two questions concerning (lithiomethyl)silanes (i) aggregation of (lithiomethyl)(aminomethyl)silanes in the solid state (ii) stabilizing effects of silicon in (lithiomethyl)silanes. 

We have prepared (aminomethyl)silanes (F) by the known reaction (i) and three new (ii-iv) synthetic routes (Scheme 1) ... 

Aminomethyl)silanes (E) can be metallated by lithiumalkyls and characterized by trapping with disulfides (Scheme 3). The (phenylthiomethyl)(aminomethyl)silanes G can be metallated again in toluene or THF In reactions of (lithiomethyl)(aminomethyl)diphenylsilanes with aldehydes or ketones we observed no clear addition/deprotonation profile. The (lithiomethyl)silanes H add to ketones with de up... 

Further related work on the synthesis, structure, and reactivity of (lithiomethyl)(aminomethyl)silanes is currently under way to understand more about the behavior of these systems in solution and in the solid state. 

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