Untersuchungen über gespannte cyclische acetylene, VI Nachweis des 1,1-dimethylsila-4-cycloheptins

Photochemical Formation of Dibenzosilacyclohept-4-yne for Cu-Free Click Chemistry with Azides and 1,2,4,5-Tetrazines

“…There are not many literature reports available describing the synthesis of silacycloheptyne derivatives . A thermal generation of 1,1-dimethylsilacyclohept-4-yne and its in situ trapping by cyclopenta-2,4-dienone was reported in the 1970s, and the authors mentioned that the compound is fairly stable in diluted dichloromethane solutions (∼100 h). The atomic radius of silicon is only slightly smaller than that of selenium, and thus, the ring strain in 3 is expected to be similar to that in 10 but certainly higher than that of eight-membered dibenzocyclooctyne.…”

Angle-strained sila-cycloalkynes

“…10 Examples of silacycloheptynes with a single CH 2 for SiMe 2 substitution have been reported by Krebs, although the products were not isolable and characterized as their trapped products. 12,13 The distortion of the acetylene bond angle away from linearity (1801), as found by X-ray crystallography, is known as angle strain. 14 Chart 1 summarizes bond angles in known silacycloalkynes, with smaller ring sizes resulting in greater distortion.…”

“…10 Examples of sila-cycloheptynes with a single CH 2 for SiMe 2 substitution have been reported by Krebs, although the products were not isolable and characterized as their trapped products. 12,13…”

Synthese und Eigenschaften von 1‐Thia‐2‐cyclooctin

“…cm) mit Petrolether (40-70"C)/Diethylether (1 : 1) chromatographiert. Als erste Fraktion eluiert man 5,6,7, [3,2-d]pyrazol(32), ein schwach gelbliches 61; Ausb. 48 mg…”