of α‐methylene‐γ‐lactones through the palladium(II)‐catalyzed lactonization of homoallylic alcohols with alkynamides has been reported. The hydroxyl group in the terminal olefins cooperates with the amide in alkynamides to promote the cyclization by suppressing the β‐H elimination. This process provides a route to construct naturally occurring biologically multifunctional α‐methylene‐γ‐lactones.
Synthesis of Tetrahydrofurans by Cyclization of Homoallylic Alcohols with Iodine/Iodine(III)
作者:Ramon S. Vasconcelos、Luiz F. Silva、Athanassios Giannis
DOI:10.1021/jo102413u
日期:2011.3.4
Tetrahydrofuran derivatives can be obtained by cyclofunctionalization of homoallylicalcohols bearing a terminal double bound by using [hydroxy(tosyloxy)iodo]benzene (HTIB, Koser’s reagent) in the presence of a catalytic amount of I2 (20 mol %) in MeOH under mild conditions. This transformation is an overall5-endo-trig cyclization, which occurs by two different pathways. The first is a 4-exo-trig
Copper‐Catalyzed Regioselective Borocarbonylative Coupling of Unactivated Alkenes with Alkyl Halides: Synthesis of β‐Boryl Ketones
作者:Fu‐Peng Wu、Yang Yuan、Claas Schünemann、Paul C. J. Kamer、Xiao‐Feng Wu
DOI:10.1002/anie.202002714
日期:2020.6.22
borocarbonylative coupling of unactivated alkenes with alkyl halides remains a challenge. In this communication, a Cu‐catalyzed borocarbonylative coupling of unactivated alkenes with alkyl halides for the synthesis of β‐boryl ketones has been developed. A broad range of β‐boryl ketone derivatives was prepared in moderate to excellent yields with complete regioselectivity.
presence of lithiumdialkylamides to functionalized 2,3-dihydropyrans or 2,3-dihydrofurans, respectively, is described. The regiochemical outcome of the reaction can be influenced by the relative configuration of the starting epoxides and the steric demand of the base. The 2,3-dihydropyrans obtained were converted stereoselectively to difunctionalized 3,4-dihydropyrans by the carbon-Ferrier reaction, or to
Diastereoselective Additions of Allylmagnesium Reagents to α-Substituted Ketones When Stereochemical Models Cannot Be Used
作者:Nicole D. Bartolo、Krystyna M. Demkiw、Elizabeth M. Valentín、Chunhua T. Hu、Alya A. Arabi、K. A. Woerpel
DOI:10.1021/acs.joc.1c00553
日期:2021.5.21
allylmagnesium reagents with chiral ketones cannot be easily explained by stereochemical models. Competition experiments indicate that the complexation step is not reversible, so nucleophiles cannot access the widest range of possible encounter complexes and therefore cannot be analyzed easily using available models. Nevertheless, additions of allylmagnesium reagents to a ketone can still be stereoselective