Vinylketenes
Vinylketenes are a class of chemical compounds where a vinyl group is conjugated to a ketene. Vinylketenes are key intermediates in the Danheiser benzannulation and Wulff-Dötz reaction, two routes to synthesis of phenols.
Preparation
[edit]Vinylketenes are typically prepared in situ. Dehydrohalogenation of butenoyl chloride produces 1,3-butadienal, with substituted acyl chlorides likewise producing substituted vinylketenes; however, this method can be undesirable as the byproduct contains organic ammonium chloride derivatives that catalyse ketene polymerisation.[1]
Vinylketenes may be prepared by electrocyclic ring opening of cyclobutenones. In the Danheiser benzannulation, vinylketene is produced via Wolff rearrangement of a vinyl-conjugated diazoketone.[2][3]
Reactions
[edit]Vinylketenes are highly reactive versus polymerisation, but can be stabilised as organometallic coordination complexes. Typically, the vinylketene is a tetrahaptic ligand similar to a diene. Vinylketenes can also exhibit dihapticity when prepared from η2(C,O) ketene complexes via an intermediate vinylogous acylium complex.[4]
Sources
[edit]- ↑ Bennett, Dawn Marie (1999-05-19). Synthesis and chemistry of (trialkylsilyl)vinylketenes (PDF) (Doctor of Philosophy thesis). Massachusetts Institute of Technology. Retrieved 2026-02-27.
- ↑ Danheiser, Rick L.; Brisbois, Ronald G.; Kowalczyk, James J.; Miller, Raymond F. (1990). "An annulation method for the synthesis of highly substituted polycyclic aromatic and heteroaromatic compounds". Journal of the American Chemical Society. 112 (8): 3093–3100. doi:10.1021/ja00164a033.
- ↑ John M. Read, Yu-Pu Wang, and Rick L. Danheiser (2016). "Photochemical Benzannulation of N-Phosphoryl Ynamides and α-Diazo Ketones in Continuous Flow". Organic Syntheses. 93: 127–145. doi:10.15227/orgsyn.093.0127
{{cite journal}}: CS1 maint: multiple names: authors list (link). - ↑ Kerr, Margaret E.; Bruno, Joseph W. (1997). "Synthesis and Reactivity of Niobium−Vinylketene Complexes Exhibiting Ketene η2-C,O Complexation". Journal of the American Chemical Society. 119 (13): 3183–3184. doi:10.1021/ja963520w.