Total Synthesis of (−)‐Salinosporamide A

A detailed description of our second‐generation total synthesis of salinosporamide A is presented. Three contiguous stereocenters in the γ‐lactam structure seen in the natural product were established by stereoselective functionalization of a D ‐arabinose scaffold, including an Overman rearrangement to generate a highly congested tetrasubstituted carbon center. One of the definitive reactions in the synthesis was a Lewis acid mediated skeletal rearrangement of a pyranose structure, which enabled the practical conversion of the carbohydrate scaffold to the γ‐lactam structure embedded in salinosporamide A. The use of a benzyl ester as a protective group for a sterically hindered carboxylic acid led to a one‐pot global deprotection at the end of the synthesis.