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.