First total syntheses of (±)-3-aza-11-selena and (±)-3-aza-11-tellura steroids

An efficient synthesis of 11-selena and 11-tellura steroids bearing a pyridine as an A ring was achieved via an intramolecular Diels-Alder cycloaddition of o-quinodimethanes, which were generated from a 3-azabicyclo[4.2.0]octa-1,3,5-trien-7-one ketal. The major isomer matches the trans-anti-trans ring configuration of natural products. Finally, the vinyl groups of the synthesized 11-hetero steroids have been oxidized by the Wacker process in good yields. The characteristic 1H and 13C NMR spectroscopic features of the synthesized compounds are reported.