Fürstner Alois, Leitner Andreas, Méndez María, Krause Helga
Max-Planck-Institut für Kohlenforschung, D-45470 Mülheim/Ruhr, Germany.
J Am Chem Soc. 2002 Nov 20;124(46):13856-63. doi: 10.1021/ja027190t.
Simple iron salts such as FeCl(n), Fe(acac)(n) (n = 2,3) or the salen complex 4 turned out to be highly efficient, cheap, toxicologically benign, and environmentally friendly precatalysts for a host of cross-coupling reactions of alkyl or aryl Grignard reagents, zincates, or organomanganese species with aryl and heteroaryl chlorides, triflates, and even tosylates. An "inorganic Grignard reagent" of the formal composition [Fe(MgX)(2)] prepared in situ likely constitutes the propagating species responsible for the catalytic turnover, which occurs in many cases at an unprecedented rate even at or below room temperature. Because of the exceptionally mild reaction conditions, a series of functional groups such as esters, ethers, nitriles, sulfonates, sulfonamides, thioethers, acetals, alkynes, and -CF(3) groups are compatible. The method also allows for consecutive cross-coupling processes in one pot, as exemplified by the efficient preparation of compound 12, and has been applied to the first synthesis of the cytotoxic marine natural product montipyridine 8. In contrast to the clean reaction of (hetero)aryl chlorides, the corresponding bromides and iodides are prone to a reduction of their C-X bonds in the presence of the iron catalyst.
简单的铁盐,如FeCl(n)、Fe(acac)(n)(n = 2,3)或salen配合物4,被证明是高效、廉价、毒理学性质良好且环境友好的预催化剂,可用于一系列烷基或芳基格氏试剂、锌酸盐或有机锰物种与芳基和杂芳基氯化物、三氟甲磺酸盐甚至对甲苯磺酸盐的交叉偶联反应。原位制备的形式组成为[Fe(MgX)(2)]的“无机格氏试剂”可能构成负责催化周转的传播物种,在许多情况下,即使在室温或室温以下,催化周转也以前所未有的速率发生。由于反应条件异常温和,一系列官能团如酯、醚、腈、磺酸盐、磺酰胺、硫醚、缩醛、炔烃和 -CF(3) 基团都是兼容的。该方法还允许在一个反应釜中进行连续的交叉偶联过程,如化合物12的有效制备所示例,并且已应用于细胞毒性海洋天然产物蒙替吡啶8的首次合成。与(杂)芳基氯化物的清洁反应相反,相应的溴化物和碘化物在铁催化剂存在下容易发生其C-X键的还原。