Bulky iodotriazolium tetrafluoroborates as highly active halogen-bonding-donor catalysts.

Steric bulk around catalytic centers is one of the most important factors determining catalytic reactivities and selectivities. This paper reports the synthesis of structurally diverse 5-iodo-3-methyl-1,2,3-triazolium salts and the evaluation of their catalytic activities as halogen-bonding donors for the aza-Diels-Alder reaction of 2-siloxy-1,3-butadiene with imines. We found that steric hindrance around an iodide atom in halogen-bonding donors significantly impacted catalytic efficiency.

Palladium-Catalyzed Formylation of Arylzinc Reagents with S-Phenyl Thioformate.

The first example of palladium-catalyzed direct formylation of arylzinc reagents using S-phenyl thioformate is reported. The reaction proceeded under mild conditions, allowing high functional group tolerance. In addition, the developed formylation method was used to prepare deuterated and 13C-labeled aryl aldehydes from isotope-labeled S-phenyl thioformates. Moreover, this procedure was applied to an alkenylzinc halide, affording the corresponding enal.