PtCl-Catalyzed Intramolecular Cyclization of α-Benzyl Allenoates to Afford Indenes and Furanones.

Indene and furanone are important ring structures widely present in active pharmaceutical molecules. Here, we have developed a straightforward method for the synthesis of indene and furanone via PtCl-catalyzed intramolecular cyclization of α-benzyl allenoates. By altering the ester substitution pattern in the α-benzyl allenoates, we can regulate the reaction site, enabling two distinct intramolecular cyclization reactions that yield both indene and furanone products, respectively.

Ligand-Controlled Regiodivergent Ring Expansion of Benzosilacyclobutenes with Alkynes Route to Axially Chiral Silacyclohexenyl Arenes.

A ligand-controlled regiodivergent and enantioselective ring expansion of benzosilacyclobutenes with internal naphthyl alkynes has been achieved by adjusting the ligand cavity size. The ligand ()-8-binaphthyl phosphoramidite, featuring small methyl groups on its arms, provides a spacious cavity that favors sterically demanding Si-Csp ring expansion, predominantly yielding axially chiral ()-1-silacyclohexenyl arenes. In contrast, the ligand ()-spiro phosphoramidite, with bulky -Bu groups on its arms, offers a compact cavity that facilitates less sterically demanding Si-Csp ring expansion, leading primarily to axially chiral ()-2-silacyclohexenyl arenes.