366011-46-3Relevant academic research and scientific papers
A mild route to α-alkoxyacetylenes mediated by Lewis acids and synthetic routes to 10-, 11-, and 12-membered ring enediyne carbocycles
Comanita, Bogdan M.,Heuft, Matthew A.,Rietveld, Tanya,Fallis, Alex G.
, p. 241 - 253 (2007/10/03)
The condensation of silyl substituted acetylenes with dimethoxy acetals via a modified "Mukaiyama-type reaction" to afford α-alkoxyacetylenes is described. These propargylic ethers 17-21 were synthesized from the reaction of aluminum or zinc acetylides with acetals mediated by Lewis acids. In appropriate cases, when a second acetal was present in the initial acyclic product (24), a subsequent intramolecular acetal-ene (Prins) cyclization ensued to afford the silylalkylidenealkoxycyclopentane (25). Enediyne species were unreactive under these conditions, even in an intramolecular case. Routes to 11-and 12-membered carbocyclic enediyne compounds (43, 44) were developed via an intramolecular pinacol coupling of the dialdehydes 39 with sammarium diodide/HMPA. The requisite double bond was introduced using the thiocarbonate expulsion method with trimethyl phosphite. A route to the highly substituted 10-membered ring enediyne 50 is also described based on the use of an isopropylidene acetal tether control group to facilitate an intramolecular chromium (II)/nickel (II)-mediated coupling of the iodoacetylene aldehyde 49.
