Synthesis, separation, and structural analysis of planar chiral carboxy-substituted [2.2]metacyclophanes
作者:Marco Blangetti、Helge Müller-Bunz、Donal F. O'Shea
DOI:10.1016/j.tet.2013.03.076
日期:2013.5
of carboxy-functionalized planar chiral [2.2]metacyclophanes from m-xylenes is described. Both transformative steps utilize LiNK metalation conditions (BuLi, KOt-Bu, TMP(H)) for m-xylene benzylic deprotonation with subsequent in situ oxidative C–C coupling. Inclusion of the carboxy substituents at either C4, or C4 and C14, renders the [2.2]metacyclophanes planar chiral and the structural analysis of
从羧基官能化的平面手性[2.2] metacyclophanes的两步合成米-xylenes进行说明。既变革步骤利用链路金属化条件锂(BuLi,KO吨为-Bu,TMP(H))米-二甲苯苄基去质子化,随后进行原位氧化性C–C偶联。在C4或C4和C14处都包含羧基取代基,使[2.2]甲基环环烯类具有平面手性,并且两种取代模式的结构分析均已通过X射线晶体学和NMR光谱法进行了分析。C4单取代和C4 / 14二取代的羧酸甲酯外消旋物很容易通过分析和制备型手性HPLC分离,在庚烷中于373 K下分别以125.3 kJ / mol和130.9 kJ / mol测得它们的转化势垒。平面手性[2.2]甲基环已烷的简便合成,分离和高转化垒为手性催化剂和配体的研究提供了机会,迄今为止尚未探索。