N-[omega-(9R)-hydroperoxy-(10E,12Z)-octadecadienoyloxy]acyl-beta-D-glucosyl-(1<->1)-octadecasphing-4E-enine = a N-[omega-(9R,10R)-epoxy-(13R)-hydroxy-(11E)-octadecenoyloxy]acyl-beta-D-glucosyl-(1<->1)-sphing-4E-enine — reaction