Enantioselective Cyclizations of Silyloxyenynes Catalyzed by Cationic Metal Phosphine Complexes
作者:Jean-François Brazeau、Suyan Zhang、Ignacio Colomer、Britton K. Corkey、F. Dean Toste
DOI:10.1021/ja210388g
日期:2012.2.8
discovery of complementary methods for enantioselective transition metal-catalyzed cyclization with silyloxyenynes has been accomplished using chiral phosphine ligands. Under palladium catalysis, 1,6-silyloxyenynes bearing a terminal alkyne led to the desired five-membered ring with high enantioselectivities (up to 91% ee). As for reactions under cationicgold catalysis, 1,6- and 1,5-silyloxyenynes
Enantioselective Conia-Ene-Type Cyclizations of Alkynyl Ketones through Cooperative Action of B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, <i>N</i>-Alkylamine and a Zn-Based Catalyst
作者:Min Cao、Ahmet Yesilcimen、Masayuki Wasa
DOI:10.1021/jacs.8b13757
日期:2019.3.13
An efficient and highly enantioselective Conia-ene-type process has been developed. Reactions are catalyzed by a combination of B(C6F5)3, an N-alkylamine and a BOX-ZnI2 complex. Specifically, through cooperative action of B(C6F5)3 and amine, ketones with poorly acidic α-C-H bonds can be converted in situ to the corresponding enolates. Subsequent enantioselective cyclization involving a BOX-ZnI2-activated
Copper-Catalyzed Oxaziridine-Mediated Oxidation of C–H Bonds
作者:Hashim F. Motiwala、Belgin Gülgeze、Jeffrey Aubé
DOI:10.1021/jo3012336
日期:2012.8.17
bonds has been observed via copper-catalyzed reactions of oxaziridines. The oxidation proceeded with a variety of substrates, primarily comprising allylic and benzylic examples, as well as one example of an otherwise unactivated tertiary C–H bond. The mechanism of the reaction is proposed to involve single-electrontransfer to the oxaziridines to generate a copper-bound radicalanion, followed by hydrogen
corresponding triflates, are subject to nucleophile-triggered fragmentation as part of a tandem process for generating functionalized alkynes. Advantages to the use of nonaflates in lieu of triflates include cost and stability. Computational analysis supports a postulated fragmentation mechanism involving a closed (cyclic) transition state with concerted extrusion of lithium sulfonate. Vinylogous acyl nonaflates
Grignard-Triggered Fragmentation of Vinylogous Acyl Triflates: Synthesis of (<i>Z</i>)-6-Heneicosen-11-one, the Douglas Fir Tussock Moth Sex Pheromone
作者:Gregory Dudley、David Jones、Shin Kamijo
DOI:10.1055/s-2006-939051
日期:——
Grignard reagents react with vinylogous acyl triflates in toluene via an addition-fragmentation sequence to afford alkynyl ketones. A streamlined synthesis of (Z)-6-heneicosen-11-one, the sex pheromone of the Douglasfirtussockmoth, illustrates the utility of this method.