Enantioselective Preparation of 4-Substituted Cyclohexenes by Radical Fragmentation of Sulfoxides
摘要:
[GRAPHICS]Radical fragmentation of o-bromophenyl sulfoxides is reported. Starting from enantiomerically pure material, 4-substituted cyclohexene derivatives have been prepared with enantiomeric excesses between 70% and 86%, The key step of the process is a diastereoselective abstraction of a hydrogen atom by the initial aryl radical. The highest enantiomeric exesses have been obtained in the presence of aluminum Lewis acids.
Triphenylphosphine-Catalyzed Alkylative Iododecarboxylation with Lithium Iodide under Visible Light
作者:Ming-Chen Fu、Jia-Xin Wang、Rui Shang
DOI:10.1021/acs.orglett.0c03173
日期:2020.11.6
light-emitting diodes, PPh3 catalyzes the iododecarboxylation of aliphatic carboxylic acid derived N-(acyloxy)phthalimide with lithiumiodide as an iodine source. The reaction delivers primary, secondary, and bridgehead tertiary alkyl iodides in acetone solvent, and the alkyl iodide products were easily used to generate C–N, C–O, C–F, and C–S bonds to allow various decarboxylative transformations without
A cobalt-catalyzed cross-coupling betweenalkyl iodides and cyclopropyl, cyclobutyl, and alkenyl Grignard reagents is disclosed. The reaction allows the introduction of strained rings on a large panel of primary and secondary alkyl iodides. The catalytic system is simple and nonexpensive, and the reaction is general, chemoselective, and diastereoconvergent. The alkene resulting from the cross-coupling
Mild and Phosphine-Free Iron-Catalyzed Cross-Coupling of Nonactivated Secondary Alkyl Halides with Alkynyl Grignard Reagents
作者:Chi Wai Cheung、Peng Ren、Xile Hu
DOI:10.1021/ol501087m
日期:2014.5.2
cross-coupling of nonactivated secondary alkylbromides and iodides with alkynyl Grignardreagents at room temperature has been developed. A wide range of secondary alkyl halides and terminal alkynes are tolerated to afford the substituted alkynes in good yields. A slight modification of the reaction protocol also allows for cross-coupling with a variety of primary alkyl halides.
A copper-catalyzedC(sp3)-Si cross-coupling of aliphatic C(sp3)-I electrophiles using a Si-B reagent as the silicon pronucleophile is reported. The reaction involves an alkyl radical intermediate that also engages in 5-exo-trig ring closures onto pendant alkenes prior to the terminating C(sp3)-Si bond formation. Several Ueno-Stork-type precursors cyclized with excellent diastereocontrol in good yields