404934-07-2Relevant articles and documents
Synthesis and heck reactions of ethenyl- and (Z)-butadien-1-yl nonaflate obtained by the fragmentation of furan derivatives
Lyapkalo, Ilya M.,Webel, Matthias,Reissig, Hans-Ulrich
, p. 4189 - 4194 (2007/10/03)
The nonaflation of lithium enolates or of silyl enol ethers, formally derived from acetaldehyde or crotonaldehyde, with nonafluorobutanesulfonyl fluoride gave ethenyl nonaflate (1b) and (Z)-buta-1,3-dien-1-yl nonaflate (2) in good yields. The required enolates were obtained by aldehyde-free routes by the lithiation of tetrahydrofuran or 2,5-dihydrofuran followed by the cyclofragmentation of the metallated heterocycles. The application of this approach to the synthesis of allenyl nonaflate 3 failed, presumably due to the intrinsic instability of this allene derivative. The nonaflates 1b and 2 were also prepared by the fluoride-catalysed reaction of the corresponding silyl enol ethers 5 and 7 with nonafluorobutanesulfonyl fluoride; however, the overall yields are slightly lower for these two-step pathways. The cyclofragmentation of lithiated 2,2-dimethyl-4-methylene-[1,3]dioxolane allowed the easy preparation of trimethylsiloxyallene (10) in moderate yield. The nonaflates 1b and 2 reacted smoothly with monosubstituted alkenes in the presence of a catalytic amount of palladium(II) acetate to give the anticipated Heck coupling products in good to moderate yields and with high stereoselectivities.
