Synthesis of Eight- and Nine-Membered Carbocycles through a Ring-Closing Metathesis/Ring Fragmentation Strategy: A Rapid and Versatile Approach to Bicyclo[6.4.0]- and Bicyclo[7.4.0]alkene Ring Systems
作者:J. Ramón Rodríguez、Luis Castedo、José L. Mascareñas
Ring-closing metathesis (RCM) of cis-2,6-dialkenyl-2-hydroxy-1-cyclohexanones affords bicyclo[3.n.1]alkenones that are easily converted into eight- or nine-membered carbocycles by oxidative cleavage of the keto-bridging tether. Since the starting cyclohexanones are readily assembled from commercially available 1,2-cyclohexanedione, the overall process constitutes a rapid and versatile route to medium-sized
Enantioselective crossed intramolecular [2+2] photocycloaddition reactions mediated by a chiral chelating Lewis acid
作者:Thomas Rigotti、Daniel P. Schwinger、Raphaela Graßl、Christian Jandl、Thorsten Bach
DOI:10.1039/d2sc00113f
日期:——
In intramolecular [2+2] photocycloaddition reactions, the two tethered olefins can approach each other in a straight or in a crossed fashion. Despite the fact that the latter reaction mode leads to intriguing, otherwise inaccessible bridged skeletons, there has so far not been any enantioselective variants thereof. This study concerned the crossed [2+2]-photocycloaddition of 2-(alkenyloxy)cyclohex-2-enones
The anionic oxy-claisen rearrangement of enolates of .alpha.-allyloxy ketones. A remarkable rate accelerating effect exhibited by the nature of the counterion
作者:Masato Koreeda、Juan I. Luengo
DOI:10.1021/ja00305a066
日期:1985.9
Transposition oxy-Claisen anionique des enolates de potassium, sodium, lithium et silyl enol ether de l'allyloxy-2 propiophenone
转位 oxy-Claisen anionique des enolates de 钾、钠、锂和甲硅烷基烯醇醚 de l'allyloxy-2 propiophenone
EPR Support for the Ketyl Radical-Anion “Triggered” [3,3]-Sigmatropic Rearrangement
作者:Eric J. Enholm、Merle A. Battiste、Maria Gallagher、Kelley M. Moran、Angelo Alberti、Maurizio Guerra、Dante Macciantelli
DOI:10.1021/jo0257748
日期:2002.9.1
New physical evidence to support a ketylradical-anion mechanism for the [3,3]-sigmatropic rearrangement is presented. With use of EPR spectroscopy, spectra are observed that can be attributed to 8, an acyl radical-anion species resulting from a [3,3]-rearrangement; this also functions as a key intermediate in the process. The spectrum of an additional paramagnetic species resulting from further addition
Directing the Stereoselectivity of the Claisen Rearrangement to Form Cyclic Ketones with Full Substitution at the α-Positions
作者:Fatimat O. Badmus、Raju S. Thombal、Satish Chandra Philkhana、Joshua A. Malone、Christian E. Bailey、Estefania Armendariz-Gonzalez、Edward W. Mureka、Cale M. Locicero、Frank R. Fronczek、Rendy Kartika
DOI:10.1021/acs.orglett.3c02752
日期:2023.10.27
We report an enantioselective synthesis of cyclic ketones with full substitutions at the α-positions in a highly diastereoselective manner. Our method is achieved by subjecting substrate motifs in 2-allyloxyenones to chiral organomagnesium reagents, which trigger the Claisen rearrangement upon direct 1,2-carbonyl addition. The observed diastereoselectivity of the allyl migration is proposed to originate