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.

In this study, a variety of α,ω-bisacylpolysilanes were synthesized via two synthetic protocols. The first method for obtaining these compounds is based on the substitution reaction of bromine either on silica gel or by the use of silver salts. Surprisingly, instead of the expected bromine substitution product PhC(O)(SiMe2)2C(O)Ph 4a, we found the formation of the diastereomer PhC(O)(SiMe2)2CBrPhOCBrPh(SiMe2)2C(O)Ph 4b indicating a more complex reaction cascade. On the other hand, the phenylated compound 3b yielded the expected bromine substitution product PhC(O)(SiPh2)2C(O)Ph 4c. For the second protocol, we utilized the Corey–Seebach approach to isolate other representatives of this compound class. We found that the substituents at the α-silicon atoms influence the selectivity of the dethioketalization. While the ethylated and phenylated disilanes 5b,c yield the expected bisacyldisilanes 6a,b, the methylated disilane 4a undergoes a BF3-induced Si–Si bond breakage followed by an intermolecular sila-aldol reaction. This hitherto unknown sila-aldol reaction results in the formation of the enantiomer PhC(O)SiMe2C(OMe)PhSiMe2F 6c in excellent yields. All isolated compounds were analyzed by a combination of NMR spectroscopy, ultraviolet–visible (UV–vis) spectroscopy, single-crystal X-ray crystallography, and mass spectrometry. Furthermore, the photochemical pathways of two representative examples (4b,c) were examined.