Cross-dehydrogenative coupling for the intermolecular C–O bond formation

Abstract

SummaryThe present review summarizes primary publications on the cross-dehydrogenative C–O coupling, with special emphasis on the studies published after 2000. The starting compound, which donates a carbon atom for the formation of a new C–O bond, is called the CH-reagent or the C-reagent, and the compound, an oxygen atom of which is involved in the new bond, is called the OH-reagent or the O-reagent. Alcohols and carboxylic acids are most commonly used as O-reagents; hydroxylamine derivatives, hydroperoxides, and sulfonic acids are employed less often. The cross-dehydrogenative C–O coupling reactions are carried out using different C-reagents, such as compounds containing directing functional groups (amide, heteroaromatic, oxime, and so on) and compounds with activated C–H bonds (aldehydes, alcohols, ketones, ethers, amines, amides, compounds containing the benzyl, allyl, or propargyl moiety). An analysis of the published data showed that the principles at the basis of a particular cross-dehydrogenative C–O coupling reaction are dictated mainly by the nature of the C-reagent. Hence, in the present review the data are classified according to the structures of C-reagents, and, in the second place, according to the type of oxidative systems. Besides the typical cross-dehydrogenative coupling reactions of CH- and OH-reagents, closely related C–H activation processes involving intermolecular C–O bond formation are discussed: acyloxylation reactions with ArI(O2CR)2 reagents and generation of O-reagents in situ from C-reagents (methylarenes, aldehydes, etc.).

Concise Total Syntheses of (+)-Haplocidine and (+)-Haplocine via Late-Stage Oxidation of (+)-Fendleridine Derivatives

“…We envisioned the N1-amide could provide the necessary guidance 32 to afford a regioselective C–H bond oxidation, offering an exciting strategy for late-stage diversification and amplification of the molecular complexity of the C19-hemiaminal ether aspidosperma alkaloids.…”

Transition-metal-catalyzed synthesis of phenols and aryl thiols

“…Notably, their protocol could be also applied in the chlorination and other C–H functionalization of (2-pyridyl)arenes. Together with this work, some other work on C–H acyloxylation provided an indirect pathway for the synthesis of phenols from arenes [54]. …”

Transition‐Metal‐Catalyzed Utilization of Methanol as a C1 Source in Organic Synthesis

“…[60] Specifically,t he oxidative formation of methyl esters from alcohols constitutes ad irect and green approach for the preparation of aromatic,a liphatic,a nd heterocyclic methyl esters. [64] In addition to all of these reports,G arg and co-workers [65] recently described the application of methanol as an ucleophile in anickel-catalyzed transformation of amides into methyl ester. [64] In addition to all of these reports,G arg and co-workers [65] recently described the application of methanol as an ucleophile in anickel-catalyzed transformation of amides into methyl ester.…”