Intramolecular Reactions of Alkynes with Furans and Electron Rich Arenes Catalyzed by PtCl<sub>2</sub>: The Role of Platinum Carbenes as Intermediates
作者:Belén Martín-Matute、Cristina Nevado、Diego J. Cárdenas、Antonio M. Echavarren
DOI:10.1021/ja029125p
日期:2003.5.1
On the basis of DFT calculations, a cyclopropyl platinacarbene complex was found as the key intermediate in the process. The cyclopropane and dihydrofuran rings of this intermediate open to form a carbonyl compound, which reacts with the platinum carbene to form an oxepin, which is in equilibrium with an arene oxide. When the reaction is carried out in the presence of water, dicarbonyl compounds are
Gold(I)-Catalyzed<i>endo</i>-Selective Intramolecular α-Alkenylation of β-Yne-Furans: Synthesis of Seven-Membered-Ring-Fused Furans and DFT Calculations
Alkenylation of furans: An efficient gold‐catalyzed endo‐selective intramolecular α‐alkenylation of β‐alkyne‐substituted furans has been developed to synthesize challenging seven‐membered‐ring‐fused furans in good to excellent yields. Preliminary DFTcalculations have been carried out to understand the experimentally observed regioselectivity. DME=1,2‐dimethoxyethane, Ts=p‐toluenesulfonyl.
Wittig rearrangement of 3-furylmethyl ethers and its application to the synthesis of dendrolasin
作者:Masayoshi Tsubuki、Hiroyuki Okita、Toshio Honda
DOI:10.1039/c39950002135
日期:——
The Wittig rearrangement of 3-furylmethyl ethers 1, proceeds efficiently to give 3-methyl-2-furylmethanols 2 or 3-furylethanols 3 depending on the basicity of the butyllithium used; synthesis of dendrolasin is achieved with the 1,2-rearrangement of 3-furylmethyl geranyl ether 5 as a key step.
Wittigrearrangement of 3-furylmethyl ethers la-i was investigated. Deprotonation of 3-furylmethyl ethers la-i with bases, such as BuLi and LDA, occurred preferentially at the allylic, propargylic, benzylic positions and α-position adjacent to carbonyl group giving the corresponding anions, which underwent 2,3- and 1,2-rearrangements to afford 3-methyl-2-furylmethanols 2a-i and 3-furylethanols 3a-f
[2 + 2 + 2]Cycloadditions of Alkynes to Furans and Thiophenes: A Cobalt-Mediated "Enol Ether Walk"
作者:Roland Boese、Daniel F. Harvey、Michael J. Malaska、K. Peter C. Vollhardt
DOI:10.1021/ja00103a039
日期:1994.11
of two alkyne units to the 2,3-double bond in furans and thiophenes to give the corresponding complexed dihydrobenzoheterocycles, in turn capable of undergoing migration of the enol ether moiety along the periphery of the cyclohexadiene ligand. In some instances the cobalt-mediated alkyne addn. occurs by apparent C-H activation of the heterocyclopentadiene, resulting in the generation of butadienylated