Rapid syntheses of (±)-pterocarpans and isoflavones via the gold-catalyzed annulation of aldehydes and alkynes

(±)-Pterocarpan and analogues (4a-c) have been synthesized efficiently via the annulation of salicylaldehydes (1a, 1b and 1c) and o-methoxymethoxylphenylacetylene (2a), followed by a one-pot reduction and acidic cyclization of the ketones (3a-c). In addition, isoflavone derivatives (5a-c) have been synthesized rapidly, in two steps, via the annulation of salicylaldehyde (1a) and arylacetylenes (2b, 2c and 2d), followed by IBX/DMSO oxidation of the isoflavanones (3d, 3e and 3f).

Graphical abstract(±)-Pterocarpan and analogues have been synthesized efficiently via the annulation of salicylaldehydes and o-methoxymethoxylphenylacetylene followed by a one-pot reduction and acidic cyclization of ketones. In addition, isoflavone derivatives have been synthesized rapidly via the annulation of salicylaldehyde and arylacetylenes followed by IBX/DMSO oxidation of the isoflavanones.Download full-size image