One-pot synthesis of 3-(pyridin-2-yl)-2,3-dihydroazetes via Rh(II)-catalyzed reaction of diazoesters with trimethylsilyl-protected 2-(pyridin-2-yl)-2H-azirines

A one-pot method for the synthesis of 3-(pyridin-2-yl)-2,3-dihydroazetes was developed on the basis of Rh2(esp)2-catalyzed reaction of diazoesters with 3-aryl-2-(pyridin-2-yl)-2H-azirines. To prevent deactivation of the catalyst with the pyridine-containing azirine reactant, the trimethylsilyl protection of pyridine nitrogen was used. The insertion and removal of the protecting group were carried out as a onepot synthesis. Reactions involving ethyl 2-diazo-3,3,3-trifluoropropanoate proceed stereoselectively with the formation of only the (2RS,3SR)-isomer of the dihydroazete, which is due to the thermodynamic control of the process.