Atmosphere atom economy

From an atom economy perspective, He and Shi achieved efficient solventless hydroarylation of alkynes. Reaction took place efficiently under air atmosphere at ambient temperature and different functional groups could be tolerated. The catalytic system employed was AuCl3/AgTfO (1 3) and both inter-molecular and intra-molec-ular processes were described [128]. 

Shi has reported a method for /V-alkylanilidc arylation by simple arenes [53], The reaction conditions include heating the anilide with excess arene in propionic acid in the presence of catalytic palladium acetate and copper triflate under oxygen atmosphere. Use of monosubstituted arenes leads to the formation of isomer mixtures however, from the point of atom economy C-H/C-H couplings are the most efficient way for formation of C-C bonds if oxygen is used as the terminal oxidant. Shi has also reported that anilides can be coupled with arylboronic acids and trialkoxyaryl-silanes [54, 55], Silver and copper salts are used as terminal oxidants. 

In 2013, Carreira and coworkers presented an attractive strategy for the synthesis of chiral pyrrolidones via ruthenium-catalyzed intramolecular hydrocar-bamoylation of allylic formamides under CO atmosphere (Eq. (7.2)) [7]. A formal ruthenium-catalyzed intramolecular insertion into the formamide C-H bond and concomitant C-C bond formation by olefin hydrocarbamoylation were involved in the reaction, which made the reaction complete atom economy. The cycliza-tion performed with a broad substrate scope. More interestingly, even homoallylic and bis-homoallylic formamide substrates were used, the reactions afforded five-membered nitrogen-containing heterocycles only. 

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