Total Synthesis of the Antibiotic Kendomycin: A Macrocyclization Using the Tsuji–Trost Etherification

Abstract

A highly stereocontrolled, convergent total synthesis of kendomycin [(À)-TAN2162], an ansa-macrocyclic antibiotic, is reported. The key of the strategy is an unprecedented Tsuji-Trost macrocyclic etherification, followed by a transannular Claisen rearrangement to construct the 18-membered carbocyclic framework. The oxa-six-and five-membered rings were also stereoselectively constructed respectively by a cascade oxidative cyclization at an unfunctionalized benzylic position and using a one-pot epoxidation/5-exo-tet epoxide opening. Scheme 1. Retrosynthetic analysis. TBS = tert-butyldimethylsilyl.Scheme 4. Complete total synthesis of 1. mCPBA = m-chloroperoxybenzoic acid, TBAF = tetra-n-butylammonium fluoride. Angewandte Chemie 4299

Divergent Synthesis of Bioactive Marine Meroterpenoids by Palladium‐Catalyzed Tandem Carbene Migratory Insertion

“…Scheme shows another synthesis of (+)‐8‐ epi ‐puupehedione ( 2 ). Treatment of 22 with IBX (2‐iodoxybenzoic acid) at room temperature for 2 h gave undesired product 24 in 43 % yield, as the sole product . Alternatively, 22 was treated with DDQ in a mixed solvent of CH 2 Cl 2 and H 2 O (10:1, v/v) at room temperature for 2 h; compound 22 underwent a facile ring‐opening reaction to give the desired product 25 in 62 % yield (Scheme ).…”