Catalytic Asymmetric Arylation of Enals to Enantioenriched Linear Trisubstituted Allylic Secondary Alcohols by using Aryl Lithiums Generated In Situ from Aryl Bromides
作者:Lei Zhang、Lin Sun、Yu-Yan Li、Yue Liu、Yong-Xin Yang、Rui Yuan、Pei Wang、Chao-Shan Da
DOI:10.1002/cctc.201300655
日期:2013.12
Reactive aryl lithiums, produced in situ from readily available and inexpensive aryl bromides and butyl lithium, were used to enantioselectively arylate a number of α‐substituted cinnamaldehydes in the presence of tetramethylethylenediamine (TMEDA), AlCl3, and Ti(OiPr)4. This enabled enantioenriched linear trisubstituted allylic secondary alcohols in the catalysis of (S)‐H8‐BINOL‐(TiOiPr)2 complex.
亲核试剂向烯醛的催化不对称加成是制备对映体富集的烯丙醇的直接方法,这对天然和药物活性化合物的合成很重要。由易得且廉价的芳基溴化物和丁基锂原位生产的反应性芳基锂,在四甲基乙二胺(TMEDA),AlCl 3和Ti(O i Pr)4存在下,用于对映选择性地芳构化许多α-取代的肉桂醛。。这使(S)‐H 8‐ BINOL‐(TiO i Pr)2催化中的对映体富集的线性三取代烯丙基仲醇复杂的。TMEDA协调了在金属转移过程中原位生成的锂盐,并有效抑制了路易斯酸性锂盐催化的有害背景反应。
Aldehydes as Photoremovable Directing Groups: Synthesis of Pyrazoles by a Photocatalyzed [3+2] Cycloaddition/Norrish Type Fragmentation Sequence