https://www.chem.ccu.edu.tw/~joyce/referance/ericyang/Coord.%20Chem.%20Rev/Coord.%20Chem.%20Rev.%202004,%20248,%202337-2364.pdf

Copper in cross-coupling reactions: The post-Ullmann chemistry

Transition metal-catalyzed cross-coupling reactions of alkyl metals and aryl halides or pseudohalides have emerged as a powerful methodology for the formation of Csp3-Csp2 bonds over the past decades.1 However, significant attention has also been focused on Pdand Ni-catalyzed Csp3-Csp2 bond-forming reactions that involve aryl metals and haloalkyl compounds lacking -hydrogen atoms as cross-coupling partners.2 In contrast, until a few years ago, few examples were reported in the literature concerning transition metalcatalyzed reactions of aryl metals with functionalized alkyl halides including R-halocarbonyl compounds and R-bromosulfones bearing -hydrogen atoms,3 and a single example of Pd-catalyzed cross-coupling reaction of aryl metals and unfunctionalized alkyl halides bearing -hydrogen atoms had been described.4 Only in recent years, successful procedures for the Pd-,5 Ni-,6 Rh-,7 Fe-,8 V-,9 Co-,10 and Cu-catalyzed11 cross-coupling reactions of aryl metals and unfunctionalized alkyl halides bearing -hydrogen atoms have been developed.12 Nevertheless, new, effective, and more environmentallybenignmethodologiesfortheformationof(cyclo)alkyl-aryl bonds, which require a reduced number of synthetic operations, have emerged as valuable alternatives to the conventional cross-coupling reactions. These methodologies (Scheme 1) are based on transition metal-catalyzed simple or 2-fold C-H bond functionalization according to the following approaches: (a) highly regioselective Pd-catalyzed direct arylation reactions of unactivated sp3-hybridized C-H bonds with aryl halides (eq a, Scheme 1);13 (b) Pd-catalyzed direct alkylation reactions of aryl C-H bonds with alkyl metals (eq b, Scheme 1);14 Au-15 or Pdcatalyzed16 direct alkylation reactions of aryl C-H bonds with alkyl halides or pseudohalides (eq c, Scheme 1); (d) Pd-catalyzed arylations of unactivated sp3-hybridized C-H bonds with aryl metals (eq d, Scheme 1);14c (e) Pd-, Ru-, or Cu-catalyzed cross-coupling reactions of sp3-hybridized C-H bonds with arylboronic acids using air as oxidant (eq d, Scheme 1);17 and (f) cross-dehydrogenative coupling of alkyl and aryl C-H bonds (eq e, Scheme 1).18 Finally, great attention, particularly in the past decade, has also been focused on the design, development, and application of transition metal-catalyzed coupling reactions of aryl halides and pseudohalides with a wide variety of substrates containing activated sp3-hybridized C-H bonds (eq f, Scheme 1). A mini-review on this topic was published by Scolastico and Poli in 1999,19 and three excellent reviews that concern the results obtained in this rapidly growing area of extensive research by the groups of Miura, Natsume, Hartwig, and Buchwald up to the end of 2002 were published by Miura,20 Hartwig,21 and Lloyd-Jones22 a few years later. However, the reviews by Miura20 and Hartwig21 were limited in that they fundamentally emphasized the author’s own work and * To whom correspondence should be addressed. E-mail: rossi@dcci.unipi.it. Chem. Rev. 2010, 110, 1082–1146 1082

Transition metal-catalyzed direct arylation of substrates with activated sp3-hybridized C-H bonds and some of their synthetic equivalents with aryl halides and pseudohalides.

Despite the problems inherent to metal-catalyzed cross-coupling reactions with alkyl halides, these reactions have become increasingly important during the last few years. Detailed mechanistic investigations have led to a variety of novel procedures for the selective cross-coupling of non-activated alkyl halides bearing β hydrogen atoms with a variety of organometallic nucleophiles under mild reaction conditions. This Minireview highlights selected examples of metal-catalyzed coupling methods and is intended to encourage chemists to exploit the potential of these approaches in organic synthesis.

Catalysts for Cross‐Coupling Reactions with Non‐activated Alkyl Halides

Easy access: An unprecedented copper-catalyzed cross-coupling reaction of the title compounds with diboron reagents is described (see scheme; Ts = 4-toluenesulfonyl). This reaction can be used to prepare both primary and secondary alkylboronic esters having diverse structures and functional groups. The resulting products would be difficult to access by other means.

Alkylboronic Esters from Copper-Catalyzed Borylation of Primary and Secondary Alkyl Halides and Pseudohalides

In den vergangenen Jahren hat das Interesse an metallkatalysierten Kreuzkupplungen mit Alkylhalogeniden stetig zugenommen, obwohl diese Reaktionen inharent problematisch sind. Detaillierte mechanistische Untersuchungen brachten eine Reihe neuer Protokolle fur die selektive Verknupfung nichtaktivierter Alkylhalogenide mit β-Wasserstoffatomen hervor. Unter milden Reaktionsbedingungen gelingen Kupplungen mit verschiedenen Organometallnucleophilen. In diesem Kurzaufsatz werden ausgewahlte Beispiele vorgestellt, die dazu anregen sollen, das Potenzial dieser wichtigen metallkatalysierten Kupplungsmethoden in der organischen Synthese zu nutzen.

Katalysatoren machen's möglich: Selektive C‐C‐Kupplungen mit nichtaktivierten Alkylhalogeniden

Cu-Catalyzed Alkylation of Grignard Reagents: A New Efficient Procedure

The presence of NMP (4–9 equiv.) clearly improves the yield and the chemoselectivity of the Cu-catalyzed alkylation of organomagnesium reagents. Thus, secondary and tertiary alkylmagnesium chlorides were used successfully for the first time in such a reaction and ester, amide, nitrile or keto groups are tolerated. The procedure is cheap, environmentally friendly and very easy to carry out (1–3% Li 2 CuCl 4 or CuCl, THF, 20°C). It is an interesting alternative to the classical alkylation of organocuprates reagents.

Michelle Jezequel

Papers

Cu-Catalyzed Alkylation of Grignard Reagents: A New Efficient Procedure

Cu-Catalyzed Alkylation of Grignard Reagents: A New Efficient Procedure.