(2S)-2-methyl-2-([1,3]dioxolan-2-yl)-6-nitro-2H-1-benzopyran

(2S,3S,4S)-2-methyl-2-([1,3]-5,5-dimethyldioxan-2-yl)-6-nitro-3,4-epoxy-3,4-dihydro-2H-1-benzopyran

(2S,3S,4R)-N''-cyano-N-(6-nitro-3,4-dihydro-3-hydroxy-2-methyl-2-([1,3]dioxolan-2-yl)-2H-benzopyran-4-yl)-N'-benzylguanidine

(2S,3S,4R)-N''-cyano-N-(6-nitro-3,4-dihydro-3-hydroxy-2-methyl-2-dimethoxymethyl-2H-benzopyran-4-yl)-N'-(4-methoxybenzyl)guanidine