Chieh-Kai Chan

Synthesis of Substituted 1,6-Diarylnaphthalenes via a Tandem Claisen Rearrangement and Ene Reaction Protocol

In this work, we developed a concise synthetic route for the synthesis of polysubstituted naphthalenes starting from commercially available isovanillin and its derivatives. Reaction with styryl bromide via O-styrylation, Claisen rearrangement, ene reaction, and O-alkylation occurred in high yields. The key structures were confirmed by single-crystal X-ray diffraction.

Bi(OTf)3-Mediated Intramolecular Olefinic Cyclization: Synthesis of Substituted Aryl-Dihydronaphthalenes and Indenes

In this article, a facile two-step and one-pot synthetic route for the preparation of substituted aryl dihydronaphthalenes starting from 2-allylbenzaldehydes via Grignard 1,2-addition and Bi(OTf)3-catalyzed intramolecular olefinic cyclization has been developed. A five-membered ring indene skeleton is also prepared via olefin isomerization, 1,2-addition followed by cyclization. Some key structures are determined using single-crystal X-ray crystallography. A possible mechanism is presented herein.

One-Pot Synthesis of 2-Cyano-1,4-diketones: Applications to Synthesis of Cyanosubstituted Furans, Pyrroles, and Dihydropyridazines

A convenient synthetic route for the construction of functionalized 2-cyano-1,4-diketones has been established from the nucleophilic substitution of 2-bromoacetophenones with NaCN via the in situ-generated β-ketonitriles. This method was further applied to the synthesis of cyanosubstituted furans, pyrroles, or dihydropyridazines, which were obtained in good to excellent yields using Bi(OTf)3, NH4OAc, or N2H4. The key structures were confirmed by X-ray single crystal diffraction analysis.