Synthesis of (-)-LL-C10037α and related manumycin-type epoxyquinols

Article abstract of DOI:10.1055/s-1995-4141

Starting with N-allyloxycarbonyl-protected 2,5-dimethoxyaniline, hypervalent iodine oxidation protocols and selective enone epoxidation provides the Streptomyces metabolite LL-C10037α in nine steps and 7-10% overall yield. In an asymmetric variant of this strategy, (R,R)-pentane-2,4-diol is used as a chiral acetalization agent. The resulting semiquinone spiroacetal, due to an ortho-acylamino substituent that restricts the 1,3-dioxane ring conformation, undergoes face-selective epoxidation and is further functionalized to give (-)-LL-C10037α in 94% ee. These pathways represent the first syntheses of the highly functionalized mC₇N core of the manumycins and have been further extended toward the preparation of analogs for SAR studies of this class of antitumor antibiotics. Manumycins inhibit the farnesylation of Ras-protein by PFTase (protein farnesyltransferase).