(3S)-3-[2-methyl-3-(3-methylbut-2-en-1-yl)oxiran-2-yl]-4-methylidenecyclohexan-1-one + reduced [NADPH--hemoprotein reductase] + O2 = 5-dehydro-6-demethoxyfumagillol + oxidized [NADPH--hemoprotein reductase] + H2O + H(+) — reaction