Effect of Increase in Steric Bulk of Aryllithium on Stereoselectivity of Boronate Complexes
作者:Habib Hussain、Syeda Rubina Gilani、Zulfiqar Ali、Imdad Hussain
DOI:10.14233/ajchem.2013.15778
日期:——
(S)-4,4,5,5-Tetramethyl-2-(4-phenylbutan-2-yl)-1,3,2-dioxaborolane was reacted with 1-bromonaphthalene and ate-complex was synthesized and this resulted product acted as nucleophile. Stereoselectivity of ate-complex was determined by reacting with different electrophiles diisopropyl azodicarboxylate (DIAD), dibenzyl azodicarboxylate (DBAD) and tropylium tetrafluoroborate. Yields and enantiomeric ratios (e.r.) were measured at -78 ºC and room temperature. It was observed that the increase in steric bulk of aryl lithium (ArLi) resulted in the lower yields and enantiomeric ratios.
(S)-4,4,5,5-四甲基-2-(4-苯基丁-2-基)-1,3,2-二氧硼杂硼烷与1-溴萘反应合成酯络合物,所得产物起反应作为亲核试剂。通过与不同的亲电子试剂偶氮二甲酸二异丙酯(DIAD)、偶氮二甲酸二苄酯(DBAD)和四氟硼酸托吡鎓反应测定ate复合物的立体选择性。产率和对映体比率 (e.r.) 在 -78 ℃ 和室温下测量。据观察,芳基锂 (ArLi) 空间体积的增加导致产率和对映体比率降低。