Total Syntheses of Sarcandrolide J and Shizukaol D: Lindenane Sesquiterpenoid [4+2] Dimers

The syntheses of members of a family of lindenane sesquiterpenoid [4+2] dimers led to the total syntheses of sarcandrolide J and shizukaol D. Inspired by a modified biosynthetic pathway, a cascade featuring furan formation/alkene isomerization/Diels–Alder cycloaddition was devised to construct the congested polycyclic architecture of the target molecules with the correct stereochemistry. This study presents a pioneering synthetic entry to this family of natural products and paves the way for fully exploring their biological functions.     

Total Synthesis of Notoamides F,I, and R and Sclerotiamide

The total synthesis of the natural indole alkaloids (+)‐notoamide F, I, and R and (−)‐sclerotiamide is described. The four heptacyclic compounds were synthesized in 10–12 steps in a convergent and highly stereoselective manner from the readily available Seebach acetal. Key steps of the synthesis include a stereoselective oxidative aza‐Prins cyclization to construct the bicyclo[2.2.2]diazaoctane, and a cobalt‐catalyzed radical cycloisomerization to create the cyclohexenyl ring.     

Unified Total Synthesis of Polyoxins J,L, and Fluorinated Analogues on the Basis of Decarbonylative Radical Coupling Reactions

Polyoxins J ( 1 a ) and L ( 1 b ) are important nucleoside antibiotics. The complex and densely functionalized dipeptide structures of 1 a and 1 b contain thymine and uracil nucleobases, respectively. Herein we report the unified total synthesis of 1 a , 1 b , and their artificial analogues 1 c and 1 d with trifluorothymine and fluorouracil structures. Decarbonylative radical coupling between α‐alkoxyacyl tellurides and a chiral glyoxylic oxime ether led to chemo‐ and stereoselective construction of the ribonucleoside α‐amino acid structures of 1 a – d without damaging the preinstalled nucleobases. The high applicability of the radical‐based methodology was further demonstrated by preparation of the trihydroxynorvaline moiety of 1 a – d . The two amino acid fragments were connected and elaborated into 1 a – d (longest linear sequence: 11 steps). Compounds 1 a and 1 b assembled in this way exhibited potent activity against true fungi, while only 1 d was active against Gram‐positive bacteria.