Room-temperature azole C-H arylations were accomplished with inexpensive copper(I) compounds by means of photoinduced catalysis. The expedient copper catalysis set the stage for site-selective C-H arylations of non-aromatic oxazolines under mild reaction conditions, and provides step-economical access to the alkaloid natural products balsoxin and texamine.

Visible-light-induced ruthenium catalysis has enabled remote CÀHa lkylations with excellent levels of position control under exceedingly mild conditions at room temperature.T he metallaphotocatalysis occurred under exogenousphotosensitizer-free conditions and features an ample substrate scope.The robust nature of the photo-induced mild meta-C À H functionalization is reflected by the broad functional group tolerance,and the reaction can be carried out in an operationally simple manner,setting the stage for challenging secondary and tertiary meta-CÀHa lkylations by ruthenaphotoredox catalysis.The development of catalytic methods for the positionselective functionalization of C À Hb onds represents ak ey challenge in molecular synthesis. [1] Thus far, chelation assistance by directing groups has been identified as av ersatile tool for site-selective CÀHmetalations. [2] Thereby,proximityinduced C À Ha ctivations have set the stage for ap lethora of ortho-selective C À Hf unctionalizations.I ns harp contrast, strategies for the assembly of meta-substituted arenes continue to be scarce.T oo vercome the challenge of meta-CÀH functionalization, useful approaches have been devised ( Figure 1). [3] Exploiting the substratesi nherent substitution pattern has proven useful, but this approach still largely suffers from limited substrate scope. [4] Directing-group-based reactions with transient norbornene mediators, [5] hydrogenbond-forming ligands, [6] or template-based directing groups [7] have recently provided significant momentum towards metadecorated arenes.W hile representing key advances,t hese methods require multistep syntheses of ligands or templates, and often give mixtures of regioisomeric products that are difficult to separate.As au niquely versatile alternative, meta-C À Hf unctionalizations through arene s-activation [8] were realized by chelation-assisted ortho-cycloruthenation. [9][10][11][12][13] Despite indisputable progress,t he s-activation approach is limited to elevated reaction temperatures,w hich resulted in signifi-cantly reduced yields and low functional group tolerance. Conversely,r oom-temperature metal-catalyzed meta-CÀH functionalization has thus far unfortunately proven elusive.During the past decade,p hoto-induced C À Hf unctionalization has emerged as ap owerful tool for molecular synthesis, [14] both in terms of classical ortho-functionalizations or with electronically biased heteroarenes. [15] In sharp contrast, within our program on metallaphotoredox-catalyzed CÀH functionalization, [16] we have now devised an unprecedented visible-light-induced meta-C À Ha lkylation at room temperature.N otable features of our findings include 1) expedient ruthenium-catalyzed meta-C À Ha lkylations,2 )visible-lightinduced metallaphotocatalysis for remote CÀHf unctionalization, 3) exogenous-photosensitizer-free photocatalysis,a nd 4) exceedingly mild reaction conditions at room temperature. Figure 1. Strategies for meta-selective CÀHfunctionalization. a) Control by steric interactions. b) Transien...

A versatile protocol for the C–H chalcogenation of indolines and indoles by means of copper catalysis was established. The C–H functionalization occurred selectively at the C7 position of indolines and exclusively at the C(2)–H bonds of indoles. The robust copper catalyst tolerated a wide range of functional groups and set the stage for the synthesis of diversely decorated indoles. Mechanistic studies were indicative of a SET-type mechanism and a facile C–H metalation being operative.

Electrooxidative peri-C–H activation was accomplished by versatile ruthenium(ii) catalysis in terms of C–H/N–H and C–H/O–H functionalization. The sustainable electrocatalysis exploited electricity, thereby avoiding the use of toxic transition metals as sacrificial oxidants.

C-H/N-O functionalizations by cobalt(III) catalysis allowed the expedient synthesis of a broad range of isoquinolines. Thus, internal and challenging terminal alkynes proved to be viable substrates for an isohypsic annulation, which was shown to proceed by a facile C-H cobaltation.