Total synthesis of everninomicin 13,384-1--Part 3: synthesis of the DE fragment and completion of the total synthesis

The stereoselective construction of the DE fragment (2) of everninomicin 13,384-1 (1) is reported. From the two possible ways of inserting the DE fragment between the A1B(A)C and FGHA2 domains of the natural product, the sequence involving the DEFGHA2 segment was found to be the most viable. This coupling was followed by attachment of a suitably protected and activated A1B(A)C fragment which led, after orthoester construction and final deprotection to the targeted everninomicin 13,384-1 (1), completing the total synthesis of this complex naturally occurring substance.