Efficient and selective: Frustrated Lewis pairs based on BF3⋅OEt2 and LiCl‐complexed tmpMg or tmpZn amides (tmp=2,2,6,6‐tetramethylpiperidyl) allow the efficient and regioselective metalation of various functionalized N heterocycles (see scheme for examples). Moreover, such metalations carried out in the presence or absence of BF3⋅OEt2 enable a complete switch of regioselectivity, thus allowing complementary functionalization.
In situ generated aryl, heteroaryl, alkyl, or benzylic polyfunctional zinc reagents obtained by the addition of zinc and LiCl to the corresponding organic iodides undergo smooth Pd(0)-catalyzed cross-coupling reactions with aryl bromides, chlorides, and triflates in the presence of PEPPSI as a catalyst. This procedure avoids the manipulation of water and air-sensitive organozinc reagents and produces cross-coupling products in high yields.
Quinine, nicotine, and related electron-rich amino-substituted pyridines were readily metalated using LiCl-solubilized TMP (2,2,6,6-tetramethylpiperidyl) bases in the presence of BF(3)·OEt(2). A full pyridine functionalization of all five positions of the pyridine ring can be realized by using an appropriate combination of TMP bases in the presence or absence of BF(3)·OEt(2).
Effizient und selektiv: Die Titelsysteme ermöglichen eine effiziente und regioselektive Metallierung vielfältiger funktionalisierter N‐Heterocyclen (Beispiel siehe Schema; tmp=2,2,6,6‐Tetramethylpiperidyl). Mit solchen Metallierungen lassen sich in An‐ oder Abwesenheit von BF3⋅OEt2 die Regioselektivitäten vollständig umschalten und so komplementäre Funktionalisierungen erzielen.
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