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。
ASYMMETRIC REDUCTION OF PROCHIRAL CYCLIC KETONES WITH LITHIUM ALUMINUM HYDRIDE PARTIALLY DECOMPOSED BY (1R,2S)-(−)-<i>N</i>-METHYLEPHEDRINE AND 2-ALKYLAMINOPYRIDINE
The title chiral hydride was found to reduce prochiral cyclicketones, affording the corresponding optically active cyclic alcohols in high optical(max. 9 8%ee) yields.
发现标题手性氢化物可还原前手性环酮,以高光学(最大 9 8%ee)产率提供相应的旋光环醇。
Catalytic enantioselective rearrangement of meso-epoxides mediated by chiral lithium amides in the presence of excess cross-linked polymer-bound lithium amides
作者:Atsushi Seki、Masatoshi Asami
DOI:10.1016/s0040-4020(02)00371-x
日期:2002.6
Insoluble polymer-bound achiral lithium dialkylamides were prepared from the corresponding cross-linked polymer-bound amines and butyllithium. The polymer-bound achiral reagent was applied to a catalytic enantioselective rearrangement of meso-epoxides as an in situ regenerating agent of a chiral lithiumamide. The efficiency of the catalytic system was improved, and chiral allylic alcohol derivatives
New pinene-derived pyridines as bidentate chiral ligands
作者:Andrei V. Malkov、Angus J.P. Stewart-Liddon、Filip Teplý、Lukáš Kobr、Kenneth W. Muir、David Haigh、Pavel Kočovský
DOI:10.1016/j.tet.2008.02.045
日期:2008.4
β-pinene 11. A copper complex of the pyridine–oxazoline ligands 8a has been found to catalyze asymmetric allylic oxidation of cyclic olefins 36a–c with good conversion rates and acceptable enantioselectivity (≤67% ee). The imidazolium salt 10 has been identified as a precursor of the corresponding N,N′-unsymmetrical N-heterocyclic carbene ligand, whose complex with palladiumcatalyzed the intramolecular
Allylic Alcohols via Catalytic Asymmetric Epoxide Rearrangement
作者:Mikael J. Södergren、Sophie K. Bertilsson、Pher G. Andersson
DOI:10.1021/ja000545t
日期:2000.7.1
Optically active allylic alcohols can be prepared via rearrangement of epoxides using chiral lithium amides, but other than for a small subset of meso-epoxides, insufficient reactivity and enantioselectivity hamper the existing methods. Furthermore, the chiral reagents are often required in large excess. This study presents a general and highlyenantioselective process that, in addition, is based on
An Intriguing Effect of Polymer-Bound Lithium Amides in Catalytic Enantioselective Rearrangement of<i>meso</i>-Epoxides Mediated by Chiral Lithium Amides
作者:Masatoshi Asami、Atsushi Seki
DOI:10.1246/cl.2002.160
日期:2002.2
dialkylamides were prepared from the corresponding polymer-bound amines and butyllithium. The reagent was successfully employed as an in situ regenerating agent of a chiral lithium amide in a catalytic enantioselective rearrangement of meso-epoxides, and chiral allylic alcohols were obtained in up to 95% ee.
聚合物结合的二烷基酰胺锂由相应的聚合物结合的胺和丁基锂制备。该试剂成功地用作手性氨基锂的原位再生剂,用于催化内消旋环氧化物的对映选择性重排,并获得高达 95% ee 的手性烯丙醇。