Knoevenagel-kondensationen mit titantetrachlorid/base—II
作者:W. Lehnert
DOI:10.1016/0040-4020(72)84029-8
日期:1972.1
the presence of titaniumtetrachloride in tetrahydrofurane and a tert. organic base. ethyl acetoacetate and ethyl nitroacetate undergo condensation with aliphatic, aromatic, and heterocyclic aldehydes to give the corresponding α,β-unsaturated α-acetyl and α-nitro carboxylic acidesters in good yields. The latter compounds are of interest in the preparation of various α-amino acids.
Acid catalyzed ring closure reactions of electrophilic alkenes
作者:Roland Verhé、Norbert de Kimpe、Dirk Courtheyn、Laurent de Buyck、Niceas Schamp
DOI:10.1016/0040-4020(82)80073-2
日期:1982.1
3-acyl-2-alkyl-4,5-dihydrofurans. Similar cyclization of α-acyl-α,β-unsaturated esters initially afforded 3-alkoxycarbonyl-2-alkyl-4,5-dihydrofurans which were transformed into 2-acylbutanolides on further reaction with sulfuric acid.
Nickel-catalyzed [3 + 2] Cycloaddition of α,β-Unsaturated Ketones with Vinyl Oxiranes
作者:Saori Sako、Takuya Kurahashi、Seijiro Matsubara
DOI:10.1246/cl.2011.808
日期:2011.8.5
A nickel-catalyzed cycloaddition of α,β-unsaturated ketones with vinyl oxiranes to afford polysubstituted tetrahydrofurans has been developed. The key intermediate is a five-membered nickelacycle, ...
A large group of derivatives of 3-furoic acid and 3-furyl ketones can be prepared in high yield by a process which consists of reacting an .alpha.,.beta.-unsaturated ketone having either an .alpha.-carboalkoxy or .alpha.-acyl group with N-bromosuccinimide and thermally cyclizing the resulting bromine containing intermediate.