Synthesis of a macrocyclic analogue of milbemycin β1; X-ray structure of (1RS, 4RS, 6SR, 7SR, 19RS)-(10Z, 12E, 16E)-6,16-dimethyl-9-hydroxy-7-methoxy-10-methoxycarbonyl-2-oxatricyclo[17.3.1.04,9]tricosa-10,12,16-trien-3-one

Abstract

The milbemycin β₁ analogue (38) has been prepared by a convergent route involving the Wittig condensation between phosphonium salt (28) and 5-hydroxy-5H-furan-2-one (11), followed by diene isomerization, transprotection, lactonization, and reduction; the structure of the ester intermediate (37) was established by X-ray crystallography.