Regioselective and Stereospecific Copper-Catalyzed Deoxygenation of Epoxides to Alkenes

Abstract

Two copper salts (Cu(CF3CO2)2 and IMesCuCl) were identified as earth-abundant, inexpensive, but effective metal catalysts together with diazo malonate for chemo-/regioselective and stereospecific deoxygenation of various epoxides with tolerance of common functional groups (alkene, ketone, ester, p-methoxybenzyl, benzyl, tert-butyldimethylsilyl, and triisopropylsilyl). In particular, the unprecedented regioselectivity allowed for the first time monodeoxygenation of diepoxides to alkenyl epoxides. Density functional theory mechanistic studies showed that the deoxygenation occurred by collapsing the free ylide, unfavoring the possible intuitive pathway via cycloreversion of possible oxetane.

Synthesis of (Z)-Cinnamate Esters by Nickel-Catalyzed Stereoinvertive Deoxygenation of trans-3-Arylglycidates

“…The use of a copper catalyst with diazomalonate to deoxygenate methyl trans -3-phenylglycidate also provided an ( E )-methyl cinnamate ester (Scheme 1 B, eq 4). 8 An excellent procedure involving stereoinvertive deoxygenation of aliphatic epoxides was reported by the groups of Coates in 2021 9 and Asako 10 in 2016 (Scheme 1 B, eq 5). The Asako group used MoO 2 Cl 2 as a catalyst with a monodentate phosphine.…”

Nanocrystals perovskites photocatalyzed singlet oxygen generation for light-driven organic reactions

“…In the case of cyclooctene reactions, the epoxide 9a is the major product with both the catalysts (42%) and the reactions are accompanied by other product in a range of yields 7-17%, confirming a poor chemoselectivity, in general. All the detected products are known compounds whose characterization is reported in literature, taken as reference [38][39][40][41][42][43][44][45][46].…”

Deoxygenation of Epoxides with Hexamethyldigermane Catalyzed by Au Nanoparticles on TiO2

“…[4] Later, several protocols were developed where in the presence of a catalytic metal, a substance that acts as reducing agent is removing the oxygen atom with generation of the alkene π system. Characteristic examples are: diazo malonate in the presence of Cu(II) [5] or Rh(II), [6] CO catalyzed by Ir(I) [7] or Mn(CO) 5…”