The EtAlCl2-mediated intramolecular addition of silyl enol ethers to both terminal and internal unactivatedalkynes, bearing alkyl and phenyl susbstituents at the alkyne moiety, proceeded exclusively in the endo-fashion to give mono- and bicyclic β,γ-unsaturated ketones in good to excellent yields. The mechanism of this regiospecific Lewis acid-assisted carbocyclization is proposed.
The EtAlCl2-mediated intramolecular addition of silyl enol ethers to both terminal and internal unactivatedalkynes, bearing alkyl and phenyl susbstituents at the alkyne moiety, gave mono- and bicyclic β,γ-unsaturated ketones in good to excellent yields. On the other hand, the silyloxy-substituted cyclic vinylsilanes were obtained in moderate to high yields when the reactions were catalyzed by B(C6F5)3
IBS-Catalyzed Oxidative Rearrangement of Tertiary Allylic Alcohols to Enones with Oxone
作者:Muhammet Uyanik、Ryota Fukatsu、Kazuaki Ishihara
DOI:10.1021/ol9013188
日期:2009.8.6
A 2-iodoxybenzenesulfonic acid (IBS)-catalyzed oxidative rearrangement of tertiary allylic alcohols to enones with powdered Oxone in the presence of potassium carbonate and tetrabutylammonium hydrogen sulfate has been developed.
Base catalysed rearrangements involving ylide intermediates. Part 5. Thermal rearrangements of 3-dimethylaminohex-5-en-l-ynes
作者:Trevor Laird、W. David Ollis、Ian O. Sutherland
DOI:10.1039/p19800001473
日期:——
Thermalrearrangements of 3-dimethylaminohex-5-en-1-ynes (5) yield biphenyls (6). The mechanism of the transformation (5)→(6) involves a sequence of (i) a [3,3] sigmatropic rearrangement, (ii) a [1,3] hydrogen shift, (iii) an electrocyclic reaction, and (iv) elimination of dimethylamine (Scheme 2).
Double Ring-Opening Reactions of <i>Bis</i>-Cyclopropanes Promoted by Iron Salts
作者:Adrian J. Highton、Tahir N. Majid、Nigel S. Simpkins
DOI:10.1055/s-1999-2582
日期:1999.2
Certain bis-cyclopropanes were prepared from the corresponding dienol silane and, on treatment with ferric salts, were found to undergo two sequential C-C bond cleavages to give products corresponding to overall two carbon ring-expansion. In one case the nature of the product obtained was found to depend upon the types of ferric salts employed.