Synthesis and Properties of Backbone Silylated Imidazol‐2‐thiones

Abstract

Imidazole‐2‐thiones have attracted considerable interest in the past as materials for potential applications in the pharmaceutical and chemical industries. Herein, the synthesis of a series of backbone silylated 1,3‐dialkylimidazol‐2‐thiones is reported. The developed synthesis protocol involves the silylation of N,N‐dimethylimidazol‐2‐thione 1 followed by the addition of organochlorosilanes RnSiCl4–n (R=Me, Ph; n=0–4) and enabled the synthesis of the C‐silylated derivatives with monocyclic, silyl‐bridged or fused tricyclic structures. Reactivity studies performed with N,N‐dimethyl‐4,5‐bistrimethylsilylimidazole‐2‐thione as a model substance showed surprisingly stable silicon‐vinyl bonds and reactivity patterns closely related to those observed for the unsilylated species 1. Combined UV‐spectroscopic and computational studies revealed only minor impact of the silyl substituents on the electronic structure of the imidazol‐2‐thione ring.

Unlocking Some Si‐Centered Reactivity of a 4,4’‐Dichloro‐1,4‐di‐hydro‐1,4‐phosphasiline

“…The reported derivatives VIII , IX [2] showed overall low‐field‐shifted heteronuclear NMR resonances (for VIII ; δ 29 Si{ 1 H} dept20=−17.7 ppm, δ 31 P{ 1 H}=−20.7 ppm; for IX ; δ 29 Si{ 1 H} dept20=−16.9 ppm, δ 31 P{ 1 H}=−36.5 ppm) compared to 4 (Figure 2). Recently discovered tricyclic imidazol‐2‐thione based 1,4‐disilacyclohexa‐2,5‐diene X was observed to have similar 29 Si{ 1 H} dept20 resonance at −24.1 ppm [20] . The reported Si‐dialkoxy compounds XI , by West [9] also showed low field‐shifted 29 Si{ 1 H}‐dept20‐NMR resonance at δ=−20.7 ppm compared to 5 (Table 1).…”