Enantiodivergent Synthesis of Both Enantiomers of Marine Alkaloids Haliclorensin and Isohaliclorensin, a Constituent of Halitulin

Starting from (3R)-5-benzotriazolyl-3-phenylperhydropyrido[2,1-b][1,3]oxazole 9, the enantiodivergent syntheses of both enantiomers of the marine alkaloids haliclorensin 1 and isohaliclorensin 3 have been achieved. Our syntheses feature ring-expansion reactions for the formation of the aza-macrocycle ring system of 3 and sequential ring-expansion reactions (aza-Claisen rearrangement and Zip reaction) for the formation of the aza-macrocycle ring system of 1.