Stereoselective Syntheses of (+)‐Broussonetine D and (+)‐Australine via a Functionalized Pyrrolidine from an Extended Chiral 1,3‐Oxazine

The asymmetric syntheses of (+)‐broussonetine D and (+)‐australine have been achieved via a functionalized pyrrolidine obtained from an extended chiral 1,3‐oxazine. The key steps include pyrrolidine formation by oxazine cleavage and diastereoselective allylation to a pyrrolidine aldehyde. (+)‐Broussonetine D and (+)‐australine were synthesized from anti , syn , syn ‐oxazine, in six steps, with an overall yield of 22.2 %, and in seven steps, with an overall yield of 33.2 %.