The Synthesis and Configurational Stability of Enantioenriched α-Thioallyllithium Compounds and the Stereochemical Course of Their Electrophilic Substitution
chiral lithium compounds. The α-thioallyllithium compounds 9 and 25 were found to be configurationally stable in THF solutions at −78 °C. These represent the first configurationally stable α-thio-substituted allyllithium compounds, and they can be utilized in asymmetric synthesis. Alkylations proceeded with stereoinversion or in an anti-SE′ process, while addition to carbonyl compounds took place in
对映体富集的S-烯丙基N-单烷基单硫代氨基甲酸酯的质子化提供了相应的手性锂化合物。发现α-硫代烯丙基锂化合物9和25在-78℃下在THF溶液中是构型稳定的。这些代表第一构型稳定的α-硫代取代的烯丙基锂化合物,它们可用于不对称合成中。烷基化以立体反转或抗-S E '过程进行,而羰基化合物的添加以顺-S E '过程进行。羟烷基化产物用作Ni 0的起始原料-催化的交叉偶联反应。
Palladium(0) catalyzed enantioselective rearrangement of O-allylic thiocarbamates to S-allylic thiocarbamates: asymmetric synthesis of allylic thiols
作者:Achim Böhme、Hans-Joachim Gais
DOI:10.1016/s0957-4166(99)00263-3
日期:1999.7
The Pd(0) catalyzed rearrangement of the O-allylic thiocarbamates rac-2a, rac-2b and rac-4 in the presence of the chiral bisphosphane 5 proceeded quantitatively and gave the S-allylic thiocarbamates 6a, 6b and 7, respectively, with 91, 92 and 97% ee, respectively, in high yields. Saponification of the S-allylic thiocarbamate 7 furnished the allylic thiol 9 with 97% ee. (C) 1999 Elsevier Science Ltd. All rights reserved.
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作者:O. G. Bondarev、K. N. Gavrilov、V. N. Tsarev、V. A. Davankov、H.-J. Gais
DOI:10.1023/a:1021324126769
日期:——
New quinine-based polyfunctional aryl phosphite was synthesized. The phosphorus center in the new compound is characterized by a large cone angle (theta = 190). The new compound can be used in the Pd-catalyzed enantioselective rearrangement of cyclic O-allylic thiocarbamate into S-allylic thiocarbamate in an optical yield of up to 47% with a quantitative conversion.
Palladium(0)-Catalyzed Enantioselective <i>O</i>,<i>S</i>-Rearrangement of Racemic <i>O</i>-Allylic Thiocarbamates: A New Entry to Enantioenriched Allylic Sulfur Compounds
作者:Hans-Joachim Gais、Achim Böhme
DOI:10.1021/jo010668b
日期:2002.2.1
operation from the corresponding N-methyl S-allylic thiocarbamate through a palladium(0)-catalyzed substitution of iodobenzene in the presence of a base. The palladium(0)-catalyzed enantioselective rearrangement of O-allylic carbamates to S-allylic carbamates has been extended from the solution phase to the solid phase by using a methyl thioisocyanate polystyrene resin. In the case investigated the enantioselectivity
of higher thermodynamic stability can be prepared in high purity under either thermal activation or palladium(0) catalysis. Although the thermodynamically less stable regioisomers of 2 are, in general, hard to be prepared in high purity, some of them (e.g., 2d and 2h′) can be obtained with an exclusive or high selectivity by the catalysis of palladium(II). The stereoisomeric pair of 2j and 2j′ can be