A CuH-catalyzed enantioselective hydroamidation reaction of vinylarenes has been developed using readily accessible 1,4,2-dioxazol-5-ones as electrophilic amidating reagents. This method provides a straightforward and efficient approach to synthesize chiral amides in good yields with high levels of enantiopurity under mild conditions. Moreover, this transformation tolerates substrates bearing a broad range of functional groups.
AC uH-catalyzed enantioselective hydroamidation reaction of vinylarenes has been developed using readily accessible 1,4,2-dioxazol-5-ones as electrophilic amidating reagents.This method provides astraightforwardand efficient approach to synthesizec hiral amides in good yields with high levels of enantiopurity under mild conditions.M oreover,t his transformation tolerates substrates bearing ab road range of functional groups.
C–H carboxylation is an attractive
way to utilize
CO2 for chemical production provided that it does not consume
resource-intensive reagents. Alkali carbonates dispersed into the
pores of mesoporous supports display strongly basic reactivity under
CO2, allowing them to be used as base promoters for C–H
carboxylation of (hetero)arenes in the absence of other reagents or
catalysts. Mesoporous oxides are convenient support materials, but
only a relatively small fraction of the dispersed carbonate (ca. 10–20%)
is converted to carboxylate products when metal oxide supports are
used. Here, we compare mesoporous oxide and carbon supports and investigate
the dependence of carbonate reactivity on the pore structure. We show
that using mesoporous carbon supports can increase the carbonate conversion
by 2–4× when compared to oxide supports. This improved
carbonate reactivity is maintained across a variety of mesoporous
carbons with different pore structures (ordered vs disordered) and
pore diameters, indicating that the dispersed carbonate is intrinsically
more reactive on the surface of a carbon material compared to an oxide
surface. Reaction of the carboxylate products with dimethyl carbonate
yields isolable methyl esters as the final product and regenerates
the dispersed carbonate. We show that mesoporous carbon supports are
robust to at least five cycles of successive C–H carboxylation
and methylation. Understanding how the support structure affects dispersed
carbonate reactivity is valuable for advancing C–H carboxylation
toward practical application and utilizing these materials in other
CO2 transformations.
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