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
A facile and atom-economic method for the synthesis of 3a,6a-dihydro-furo[2,3-b]furan derivatives and polysubstituted furans starting from furylcarbionls has been developed. This protocol involved a domino Claisen rearrangement/dearomatizing electrocyclic ring-closure/aromatizing electrocyclic ring-opening sequence.
Regioselective reductive opening of substituted phthalans: synthetic applications
作者:Daniel García、Francisco Foubelo、Miguel Yus
DOI:10.1016/j.tet.2008.02.072
日期:2008.5
The reductive opening of substituted phthalans 6, 11, 12, 20, 21 and 28 with lithium and a catalytic amount of DTBB leads to the formation of corresponding functionalised organolithium intermediates 8, 15, 16, 23, 25 and 29+30 in a regioselective manner. The further reaction of these dianions with different electrophiles, mainly carbonyl compounds, gives the expected functionalised benzylic alcohols 9, 17, 18, 24, 26 and 31+32. The observed stereochemistry can be easily explained taking into account the values of the electron densities deduced by semiempirical PM3 calculations. (c) 2008 Elsevier Ltd. All rights reserved.
A Novel Entry to Functionalized Benzofurans and Indoles <i>via</i> Palladium(0)-Catalyzed Arylative Dearomatization of Furans
A novel entry to functionalized benzofurans and indoles from furans in moderate to good yields has been developed. This protocol involves palladium(0)-catalyzed dearomatizing intramolecular arylation of the furan ring, formation of a pi-allylic palladium complex, furan ring opening, and a beta-hydride elimination sequence.