Deoxygenative Transition-Metal-Promoted Reductive Coupling and Cross-Coupling of Alcohols and Epoxides

Abstract

The prospective utilization of abundant, CO2-neutral, renewable feedstocks is driving the discovery and development of new reactions that refunctionalize oxygen-rich substrates such as alcohols and polyols through C–O bond activation. In this review, we highlight the development of transition-metal-promoted reactions of renewable alcohols and epoxides that result in carbon–carbon bond-formation. These include reductive self-coupling reactions and cross-coupling reactions of alcohols with alkenes and arene derivatives. Early approaches to reductive couplings employed stoichiometric amounts of low-valent transition-metal reagents to form the corresponding hydrocarbon dimers. More recently, the use of redox-active transition-metal catalysts together with a reductant has enhanced the practical applications and scope of the reductive coupling of alcohols. Inclusion of other reaction partners with alcohols such as unsaturated hydrocarbons and main-group organometallics has further expanded the diversity of carbon skeletons accessible and the potential for applications in chemical synthesis. Catalytic reductive coupling and cross-coupling reactions of epoxides are also highlighted. Mechanistic insights into the means of C–O activation and C–C bond formation, where available, are also highlighted.1 Introduction2 Stoichiometric Reductive Coupling of Alcohols3 Catalytic Reductive Coupling of Alcohols3.1 Heterogeneous Catalysis3.2 Homogeneous Catalysis4 Reductive Cross-Coupling of Alcohols4.1 Reductive Alkylation4.2 Reductive Addition to Olefins5 Epoxide Reductive Coupling Reactions6 Conclusions and Future Directions

Alcohols as Substrates in Transition-Metal-Catalyzed Arylation, Alkylation, and Related Reactions

“…The deoxygenative transition-metal-catalyzed cross-coupling of two unprotected alcohols has scarcely been reported. For further discussion on related cross-electrophile coupling, we recommend the account from Gong on the use of alcohol derivatives and the review from Nicholas that describes diverse applications of alcohols and epoxides …”

“…For further discussion on related cross-electrophile coupling, we recommend the account from Gong on the use of alcohol derivatives 193 and the review from Nicholas that describes diverse applications of alcohols and epoxides. 194 2.2.4. π-Activated Alcohols with Arenes, Alkenes, Enols, and Other π-Nucleophiles. π-Activated alcohols can be coupled with a range of unsaturated compounds such as alkenes, alkynes, and arenes via cross-coupling and related transformations to forge new C−C bonds.…”

A practical flow synthesis of hydrazine derivatives from alcohols

“…Generally, these approaches mostly involve a two-electron pathway, and require a transition-metal catalyst or a good leaving group. [20][21][22][23] In 1967, Mitsunobu et al found that alcohols could undergo phosphorylation to give phosphate esters in the presence of Ph 3 P and diethyl azodicarboxylate (DEAD). 24 With its broad scope, stereospecificity and mild reaction conditions, the Mitsunobu reaction has become widely used.…”