Total and formal enantioselective synthesis of lyngbic acid and hermitamides A and B

The synthesis of lyngbic acid and both hermitamides A and B, three compounds previously isolated from Lyngbya majuscula has been achieved by a cross-metathesis between 4-methoxyundec-1-ene with pent-4-enoic acid or its amides. The reaction proceeds smoothly to deliver the target molecules in appreciable yields and with a very high E selectivity as determined by NMR experiments. Allyl transfer using a camphor derived homoallylic alcohol allowed the synthesis of enantiomerically enriched starting materials.