A conceptually novel approach is described for the synthesis of six-membered cyclic carbonates derived from carbon dioxide. The approach utilizes homoallylic precursors that are converted into five-membered cyclic carbonates having a b-positioned alcohol group in one of the ring substituents. The activation of the pendent alcohol group through an Nheterocyclic base allows equilibration towards a thermodynamically disfavored six-membered carbonate analogue that can be trapped by an acylating agent. Various control experiments and computational analysis of this manifold are in line with a process that is primarily dictated by a kinetically controlled acylation step. This cascade process delivers an ample diversity of six-membered cyclic carbonates in excellent yields and chemoselectivities under mild reaction conditions.
Tetrazolium
salts are biologically active molecules that have found
broad applications in biochemical assays. A regioselective synthesis
of tetrazolium salts is described through a formal (3 + 2) cycloaddition.
The possibility of employing simple amides and azides as starting
material and the mild conditions allow a broad functional group tolerance.
A conceptually novel approach is described for the synthesis of six-membered cyclic carbonates derived from carbon dioxide. The approach utilizes homoallylic precursors that are converted into five-membered cyclic carbonates having a b-positioned alcohol group in one of the ring substituents. The activation of the pendent alcohol group through an Nheterocyclic base allows equilibration towards a thermodynamically disfavored six-membered carbonate analogue that can be trapped by an acylating agent. Various control experiments and computational analysis of this manifold are in line with a process that is primarily dictated by a kinetically controlled acylation step. This cascade process delivers an ample diversity of six-membered cyclic carbonates in excellent yields and chemoselectivities under mild reaction conditions.
<div>A conceptually novel approach is described for the</div><div>synthesis of larger-ring cyclic carbonates derived from carbon dioxide. The approach utilizes homoallylic precursors that are converted into five-membered cyclic carbonates having a beta-positioned alcohol group in one of the ring substituents. The activation of the pendent alcohol group through an N-heterocyclic base allows for equilibration towards a thermodynamically disfavored six-membered carbonate analogue that can be conveniently trapped by an acylation agent. Various control experiments and computational analysis of this manifold are in line with a process that is primarily dictated by a kinetically controlled acylation step. This cascade process delivers an ample diversity of novel six-membered cyclic carbonates in excellent yields and chemoselectivities under remarkably mild reaction conditions. This newly developed protocol helps to expand the repertoire of CO2-based heterocycles that are otherwise difficult to generate by conventional approaches.</div>
<div>A conceptually novel approach is described for the</div><div>synthesis of larger-ring cyclic carbonates derived from carbon dioxide. The approach utilizes homoallylic precursors that are converted into five-membered cyclic carbonates having a beta-positioned alcohol group in one of the ring substituents. The activation of the pendent alcohol group through an N-heterocyclic base allows for equilibration towards a thermodynamically disfavored six-membered carbonate analogue that can be conveniently trapped by an acylation agent. Various control experiments and computational analysis of this manifold are in line with a process that is primarily dictated by a kinetically controlled acylation step. This cascade process delivers an ample diversity of novel six-membered cyclic carbonates in excellent yields and chemoselectivities under remarkably mild reaction conditions. This newly developed protocol helps to expand the repertoire of CO2-based heterocycles that are otherwise difficult to generate by conventional approaches.</div>
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