2-(1'(S), 2'(S)-Dihydroxyhex-3'-ene-yl)-3-methyl-8(S)-methoxy- S-benzoyl-9(R)-hydroxy-(5S)-1-oxa-7-aza-spiro 4.4 non-2-ene-4,6-dione 58523-30-1 Pseurotin Pseurotin A