Unanticipated participation of HCl in nucleophilic chlorination reaction: expedient route to meta chlorophenols

Pd-Catalyzed tandem C–C/C–O/C–H single bond cleavage of 3-allyloxybenzocyclobutenols

A Pd-catalyzed skeletal rearrangement of 3-allyloxybenzocyclobutenols was achieved, which involved tandem C–C/C–O bond cleavage and C–H allylic substitution.

Oxidative Photocatalytic Homo- and Cross-Coupling of Phenols: Nonenzymatic, Catalytic Method for Coupling Tyrosine

The oxidative photocatalytic method for phenol-phenol homo-coupling and cross-coupling is described and isolated yields of 16-97% are obtained. Measured oxidation potentials and computed nucleophilicity parameters support a mechanism of nucleophilic attack of one partner onto the oxidized neutral radical form of the other partner. Understanding of this model permitted development of cross-coupling reactions between nucleophilic phenols/arenes and easily oxidized phenols with high selectivity and efficiency. A highlight of this method is that one equivalent of each coupling partner is utilized. Building on these findings, a non-enzymatic, catalytic method for coupling tyrosine was also developed.

Facile construction of diverse polyheterocyclic scaffolds via gold-catalysed dearomative spirocyclization/1,6-addition cascade

A post-Ugi gold-catalysed chemo- and diastereo-selective cascade dearomative spirocyclization/1,6-addition sequence is disclosed for the facile synthesis of diverse fused polyheterocyclic scaffolds bearing indole, pyrrole, benzothiophene, furan or electron-rich arene cores.

Organocatalytic Chemoselective Primary Alcohol Oxidation and Subsequent Cleavage of Lignin Model Compounds and Lignin

A one-pot two-step degradation of lignin β-O-4 model compounds initiated by preferred oxidation of the primary over the secondary hydroxyl groups with a TEMPO/DAIB system has been developed [TEMPO=2,2,6,6-tetramethylpiperidine-N-oxyl, DAIB=(diacetoxy)iodobenzene]. The oxidised products are then cleaved by proline-catalysed retro-aldol reactions. This degradation methodology produces simple aromatics in good yields from lignin model compounds at room temperature with an extension to organosolv beech-wood lignin (L1) resulting in known cleavage products.

Total Synthesis of Kehokorins A-E, Cytotoxic p-Terphenyls

This paper describes a general method for the synthesis of kehokorins A-E, novel cytotoxic p-terphenyls. 2,4,6-Trihydroxybenzaldehyde served as a common building block for preparation of the central aromatic ring. Construction of their p-terphenyl skeletons was achieved by a stepwise Suzuki-Miyaura coupling, whereas the phenyldibenzofuran moiety was built up by an intramolecular Ullmann reaction. Introduction of an l-rhamnose residue into partly protected kehokorin B was performed by the trichloroacetimidate method.