Stereoisomerically Pure Trisubstituted Vinylaluminum Reagents and their Utility in Copper‐Catalyzed Enantioselective Synthesis of 1,4‐Dienes Containing
<i>Z</i>
or
<i>E</i>
Alkenes
作者:Katsuhiro Akiyama、Fang Gao、Amir H. Hoveyda
DOI:10.1002/anie.200905223
日期:2010.1.8
The desired isomer of a chiral 1,4‐diene containing an E or Z double bond can be accessed readily by a regio‐ and stereoselective hydroalumination of silyl‐substituted alkynes and subsequent enantioselective copper‐catalyzed allylic alkylation. The utility of the procedure was demonstrated through the synthesis of (−)‐nyasol (see scheme). dibal‐H=diisobutylaluminum hydride, NHC=N‐heterocyclic carbene
Catalytic Enantioselective Conjugate Addition of Stereodefined Di‐ and Trisubstituted Alkenylaluminum Compounds to Acyclic Enones
作者:Kevin P. McGrath、Aran K. Hubbell、Yuebiao Zhou、Damián Padín Santos、Sebastian Torker、Filippo Romiti、Amir H. Hoveyda
DOI:10.1002/adsc.201901435
日期:2020.1.23
Catalytic enantioselectiveconjugateaddition (ECA) reactions with readily accessible and stereochemically defined E‐, Z‐, di‐ and trisubstituted alkenyl aluminum compounds are disclosed. Transformations are promoted by various NHC‐copper catalysts (NHC=N‐heterocyclic carbene), which are derived from enantiomerically pure sulfonate imidazolinium salts. The desired products were obtained in up to 89%
Sterically Directed Iridium-Catalyzed Hydrosilylation of Alkenes in the Presence of Alkynes
作者:Jill A. Muchnij、Farai B. Kwaramba、Ronald J. Rahaim
DOI:10.1021/ol5000549
日期:2014.3.7
A selective iridium catalyzed hydrosilylation of alkenes in the presence of more reactive alkynes is described. By utilizing [IrCl(COD)]2 in the presence of excess COD, hydrosilylation of alkenes and alkynes with ethynylsilanes is achieved with good chemo- and regioselectivity. This approach goes against the traditional reactivity trends of platinum and rhodium catalysts and allows access to highly
Unusual Tandem Alkynylation and <i>trans</i>-Hydrosilylation To Form Oxasilacyclopentenes
作者:Sarah V. Maifeld、Daesung Lee
DOI:10.1021/ol051996r
日期:2005.10.1
[GRAPHICS]An unusual tandem reaction sequence to form oxasilacyclopentenes from carbonyls and alkynylsilanes in the presence of a catalytic amount of nucleophilic initiator has been discovered. The reaction proceeds readily at room temperature and is applicable to a wide variety of carbonyl substrates. While the reaction scope tolerates variable substitutions on the alkynylsilane, phenylacetylene-derived silane variants consistently achieved the best yield.
Catalytic Oxidation of Silanes by Carbon Nanotube-Gold Nanohybrids
Turning over silanes: The first nanotube‐based catalytic system for silaneoxidation is reported (see scheme). The reusable gold–nanotube hybrid cleanly oxidizes both alkyl and aryl silanes in high yields, under mild reaction conditions, and compares most favorably to any other catalytic system in terms of overall efficacy and turnover values.