GENERATION OF CONFIGURATIONALLY STABLE, ENANTIOENRICHED ALPHA-OXY-ALPHA-METHYLBENZYLLITHIUM - STEREODIVERGENCE OF ITS ELECTROPHILIC SUBSTITUTION
GENERATION OF CONFIGURATIONALLY STABLE, ENANTIOENRICHED ALPHA-OXY-ALPHA-METHYLBENZYLLITHIUM - STEREODIVERGENCE OF ITS ELECTROPHILIC SUBSTITUTION
复制标题
DOI：
10.1016/s0040-4020(01)90461-2
复制
发表时间：
1994-05-16
期刊：
影响因子：
2.1
通讯作者：
HOPPE, D
中科院分区：
文献类型：
--
作者：
CARSTENS, A;HOPPE, D
在非极性溶剂（例如乙醚或己烷）中，在-78 ℃下用仲丁基锂/TMEDA使（R）-或（S）-1-苯乙基N，N-二异丙基氨基甲酸酯去质子化，产生构型稳定的离子对，其被不同的亲电试剂立体特异性取代。在几个实例中，分别实现了完全的立体保持或倒置。具有低能量LUMO的亲电子物质，例如酰氯、杂累积多烯和三烷基氯化锡，更喜欢抗面攻击。如果离去基团具有与锂阳离子相互作用的高倾向，例如在酯中，则发生具有保留的表面取代。
The deprotonation of (R)- or (S)-1-phenylethyl N,N-diisopropylcarbamate with s-butyllithium/TMEDA in unpolar solvents (e.g. ether or hexane) at -78 degrees C produces configurationally stable ion pairs which are substituted stereospecifically by different electrophiles. In several examples, complete stereoretention or inversion, respectively, was achieved. Electrophiles, which have an energetically low LUMO, such as acid chlorides, heterocumulenes and trialkyltin chlorides prefer antarafacial attack. If the leaving group has a high tendency to interact with the lithium cation, such as in esters, suprafacial substitution with retention takes place.