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.

A silver-catalyzed cascade conversion of modular alkyne-1,n-diols and carbon dioxide has been developed allowing for the selective formation of keto-functionalized cyclic carbonates. The protocol is characterized by its operational simplicity, excellent scope of carbonate-based heterocycles, and mild reaction conditions. In situ IR studies, control experiments, and detailed computational analysis of these manifolds reveal the intermediacy of an α-alkylidene carbonate that is intercepted by an intramolecular alcohol nucleophile. The synthetic potential of this conceptually attractive CO 2 transformation is demonstrated in the preparation of larger ring carbonates and their thermal rearrangement to sterically crowded, five-membered fused carbonate products.

A Ni-mediated decarboxylative silylation of alkynyl cyclic carbonates used as versatile propargylic surrogates is reported affording a wide range of highly substituted 2,3- and 3,4-allenol products in good yields. The formal cross-coupling between a tentative intermediate Ni­(allenyl) and the silyl reagent was further extended to enantiospecific conversions providing access to chiral allene synthons. This protocol marks the first Ni-catalyzed propargylic silylation proceeding through an SN2′ manifold.

Structurally diverse heterobicyclic diethers can be conveniently accessed in good yields through a catalytic domino process that is controlled by a versatile binary catalyst comprising an Al­(III) aminotriphenolate complex and a bromide salt. These bicycles, representing non-natural, 3,5-anhydro furanose mimics, are derived from bis-epoxy substrates through a double cyclization pathway that is initiated by the activation of the free alcohol in the precursor compounds. Various mechanistic control experiments, X-ray analyses, and computational investigations allowed us to rationalize the intricacies of this multistep process and the role of each catalyst component while revealing a clear preference for a sequence that starts with oxetane ring formation followed by an annulation step forming a fused and substituted tetrahydrofuran.