Baclofen is an antispastic drug used as a muscle relaxant in the treatment of the paroxysmal pain of trigeminal neuralgia, spasticity of the spinal cord and cerebral origin. Baclofen resides biological activity exclusively in its (R)-(–)-enantiomer. In this review, various asymmetric synthetic strategies for (R)-(–)-baclofen are described.1 Introduction2 Resolution Synthetic Approaches2.1 Chemical Resolution2.2 Biocatalytic Resolution3 Asymmetric Desymmetrization3.1 Catalytic Enantioselective Desymmetrization3.2 Enzymatic Desymmetrization4 Chiral Auxiliary Induced Asymmetric Synthesis4.1 Asymmetric Michael Addition4.2 Asymmetric Aldol Addition4.3 Asymmetric Nucleophilic Substitution5 Asymmetric Reduction5.1 Catalytic Asymmetric Hydrogenation5.2 Bioreduction6 Catalytic Asymmetric Conjugate Addition7 Conclusion

A general strategy for the stereoselective total syntheses of cladospolides A, B, and C and iso‐cladospolide B has been accomplished. The key steps provide easy access to the target molecules and include an alkyne‐zipper reaction, a Sharpless asymmetric epoxidation/dihydroxylation, and a Yamaguchi macrolactonization. The feasibility of the alkyne‐mediated approach to construct the required carbon framework as well as to create the diol functionality and the olefin geometry is successfully demonstrated.

A stereoselective formal synthesis of a 16-membered antibiotic macrolide (-)-A26771B is described starting from (R)-propylene oxide and (+)-diethyl tartrate. Key steps involved in this alkyne-assisted convergent approach are alkyne zipper reaction, Cadiot-Chodkiewicz coupling, and Yamaguchi macrolactonization.

Helv eticaChimica Acta -V ol. 98 (2015)9 67 2015 Verlag Helvetica Chimica Acta AG,Z ürich Figure. Structuresof5 -hydroxy-4-decanolides, 1a -1d,and (À)-muricatacin (2) Helv eticaChimica Acta -V ol. 98 (2015) 969Scheme2. Synthesis of (4R,5R)-5-Hydroxy-4-decanolide (1a)Scheme 3. Synthesiso f( À)-Muricatacin (2)