Transition metal-catalyzed C–H bond functionalizations by the use of diverse directing groups

Abstract

In this review, a summary of transition metal-catalyzed C–H activation by utilizing the functionalities as directing groups is presented.

Selectivity Control in the Palladium-catalyzed Cross-coupling of Alkyl Nucleophiles

“…[3] In particular, a range of mono-and bidentate directing groups have been developed to perform site-selective C(sp 3 )-H activation via the formation of small (four to six-membered) palladacycles, followed by ipso functionalization (Scheme 1a). [4] Another strategy that we have been actively pursuing, employs oxidative addition to palladium(0) instead of coordination to palladium(ii) in the step preceding C-H activation, and allows the creation of a wide variety of rings. [5] More recently, we have designed a different strategy based on a migratory, 'chain walking' cross-coupling mechanism (Scheme 1b).…”

Synthesis of Isoquinolinones via Regioselective Palladium-Catalyzed C–H Activation/Annulation

“…These transformations, which involve a metal-promoted activation of "inert" C-H bonds and cycloadditions of unsaturated substrates, allow the formation of cyclic products from readily available precursors in a rapid and atom-economical manner. Palladium [25,26], rhodium [27,28], and ruthenium [29,30] are among the most frequently used transition-metal catalysts for this activation/annulation; the applications of first-row transition metals, such as cobalt [31] and copper [32], have also been reported in these processes.…”

Synthesis of Tetrahydrobiphenylene <i>via</i> Pd(0)-Catalyzed C(<i>sp</i>²)–H Functionalization

“…When other organic (Et 3 N) and inorganic (KOAc, Na 2 CO 3 , and K 2 CO 3 ) bases were employed, the reaction hardly proceeded, or gave the desired product 2a in low yields (entries [11][12][13][14]. The addition of PivOH was not essential, but it gave a more improved yield, than the use of 1-adamantanecarboxylic acid (AdCOOH) or cesium pivalate (CsOPiv) (entries [15][16][17]. Unexpectedly, PivNHOH, which was effective for benzylic C(sp 3 )-H functionalization in the synthesis of oxindoles, completely suppressed the formation of the tetrahydrobiphenylene (entry 18).…”

“…[13][14][15][16][17][18][19][20] Methods for the formation of benzocyclobutenes based on intramolecular C-H functionalization have been developed by the Catellani, Baudoin, Wolfe, and Martin groups. [21][22][23][24][25][26][27] Recently, we have investigated Pd(0)-catalyzed benzylic C(sp 3 )-H functionalization for the synthesis of various heterocycles and tetrahydro-2H-fluorenes.…”