New chiral diselenides were prepared in a few steps from readily available starting materials. The seleniumelectrophiles generated from these diselenides were used for the efficient stereoselective inter- and intramolecular functionalization of alkenes. The substitution pattern influences the stereoselectivities and protection of the hydroxy moiety in the chiral side chain led to increased selectivities
Synthesis of Chiral Acetals by Asymmetric Selenenylations
作者:Lars Uehlin、Thomas Wirth
DOI:10.1080/10426500902930167
日期:2009.6.23
Asymmetric selenenylations of (E)-ethoxystyrene are described leading to chiralacetals. An efficient synthesis of such compounds including the determination of their absolute configuration is described.
The simple substitution of an aryl proton by a methoxy substituent improves the selectivity of the stereoselective selenenylation reaction dramatically, leading to addition products with diastereomeric ratios up to 50:1 in the methoxyselenenylation reaction of styrene.
Stereoselective Isoquinoline Alkaloid Synthesis with New Diselenides
作者:Thomas Wirth、Gianfranco Fragale
DOI:10.1055/s-1998-2011
日期:1998.2
The synthesis of improved optically active selenium compounds for electrophilic additions to C=C double bonds is described. These reagents allow the formation of methoxyselenenylated products with high diastereoselectivities (up to 93% de). Intramolecular aminoselenenylations with chiral selenium electrophiles provide a short route to tetrahydroisoquinoline alkaloids.
Mechanistic Course of the Asymmetric Methoxyselenenylation Reaction
作者:Thomas Wirth、Gianfranco Fragale、Martin Spichty
DOI:10.1021/ja974177d
日期:1998.4.1
competition experiments it was shown that the formation of these intermediates is reversible. The seleniranium ions of type 20 + formed by addition of chiralseleniumelectrophiles to alkenes are the decisive intermediates in the asymmetricmethoxyselenenylation reaction. Their stabilities are strongly dependent on the strength of the selenium-heteroatom interaction. This was shown experimentally, because