研究了几种导致非对映异构的二仲1,4-二醇及其1,4-二磺酸酯消除环化的方法,这些方法导致形成四氢呋喃,并发现它们均通过S N 2型机理进行立体选择,在一个(1,4-二醇)或两个(1,4-二磺酸酯)手性中心构型反转,因此内消旋(即赤型)1,4-二醇和±(即苏式)1,4-二甲磺酸酯仅提供反式-2,5-二烷基四氢呋喃,而相应的非对映异构底物仅转化为顺式-2,5-二烷基四氢呋喃。
Chiral amine–imine ligands based on trans-2,5-disubstituted pyrrolidines and their application in the palladium-catalyzed allylic alkylation
作者:Hongfeng Chen、James A. Sweet、Kin-Chung Lam、Arnold L. Rheingold、Dominic V. McGrath
DOI:10.1016/j.tetasy.2009.07.010
日期:2009.7
moiety affords dramatic changes on the outcome of the stereochemistry. Evidencefrom various studies suggested that during the palladium-catalyzed allylic alkylation reaction, nucleophilicattack onto the 1,3-diphenylallyl moiety in the transition state occurs mainly trans to the pyridine ring of the less stable conformation of the palladiumcomplexes.
palladium‐catalyzed enantioselectiveCHfunctionalization of indoles was achieved with an axiallychiral2,2′‐bipyridine ligand, thus providing the desired indol‐3‐acetate derivatives with up to 98 % ee. Moreover, the reaction protocol was also effective for asymmetric OH insertion reaction of phenols using α‐aryl‐α‐diazoacetates. This represents the first successful application of bipyridine ligands with axial
轴向手性的2,2'-联吡啶配体实现了钯催化对映体的C C H的对映选择性CH官能化,从而提供了所需的吲哚-3-乙酸酯衍生物,其ee高达98%。此外,该反应方案对于使用α-芳基-α-重氮乙酸酯的酚的不对称OH插入反应也有效。这代表具有轴向手性的联吡啶配体在钯催化的卡宾迁移插入反应中的首次成功应用。
Imidazolium-based chiral ionic liquids: synthesis and application
作者:Yumiko Suzuki、Junichiro Wakatsuki、Mariko Tsubaki、Masayuki Sato
DOI:10.1016/j.tet.2013.09.017
日期:2013.11
centers on N-substituents is reported. [(2S,3S)-2,3-Dihydroxybutane-1,4-bis(3-butylimidazolium)]-[bis(trifluoromethanesulfonyl)amide]2 and [(4S,5S)-2-phenyl-1,3-dioxolane-4,5-bis(1-methylimidazolium)]-[bis(trifluoromethanesulfonyl)amide]2 induced enantioselectivity in the Michael addition of malonicesters to chalcones.
New chiral phospholanes; Synthesis, characterization, and use in asymmetric hydrogenation reactions
作者:Mark J. Burk、John E. Feaster、Richard L. Harlow
DOI:10.1016/s0957-4166(00)86109-1
日期:1991.1
5-disubstituted-1-phenylphospholanes which are then employed in the preparation of a new series of C2-symmetric bis- and C3-symmetric tris(phospholane) ligands. A versatile three-step route to the important chiral 1,4-diol intermediates, used in the phosphinesyntheses, is outlined. Rhodiumcomplexes bearing the newphosphineligands were prepared and shown to act as efficient catalyst precursors for the enantioselective
Asymmetric synthesis of trans-2,5-dimethylpyrrolidine
作者:Mariel E. Zwaagstra、Auke Meetsma、Ben L. Feringa
DOI:10.1016/s0957-4166(00)80066-x
日期:1993.10
A new synthetic route to (2S,5S)-dimethylpyrrolidine 1, which can also be applied to the synthesis of the (2R,5R)-enantiomer, has been developed. The C2-symmetric pyrrolidine can be obtained enantiomericallypure (e.e. ⩾ 97%) in 15% overall yield starting from a mixture of isomers of 2,5-hexanediol, via a short reaction sequence using (S)-α-methylbenzylamine as a chiral auxiliary. The crystal and molecular
已开发出一种新的合成路线,以合成(2S,5S)-二甲基吡咯烷1,该路线也可用于合成(2R,5R)-对映体。以2,5-己二醇的异构体混合物为原料,经短时间的反应,使用(S)-α-甲基苄胺作为对映体,可以以15%的总收率获得对映体纯的C 2对称吡咯烷(ee ee 97%)。手性助剂。还报道了(S)-2'-苯基-N-乙基-(2S,5S)-二甲基吡咯烷苦味酸盐5的晶体和分子结构,其显示了苦味酸盐单元的反平行堆叠。