... 8-[ 1-oxo-3(R)-isopropoxy-butyl ]-5 ,7-dimethoxy- 2,2-dimethyl- 2H-1-benzopyran (MA20D); ã 8-( 1-oxobut-2-en-1-yl )-5 ,7-dimethoxy-3-nitro-2,2-dimethyl-2H-1-benzopyran (MA20B); ã 1-( 5,7-dimethoxy-2,2-dimethyl-2H-chromen-8-yl)-butan-1-one ... 8-[ 1-oxo-3(R)-isopropoxy-butyl ]-5 ,7-dimethoxy- 2,2-dimethyl- 2H-1-benzopyran (MA20D); ã 8-( 1-oxobut-2-en-1-yl )-5 ,7-dimethoxy- 3- nitro -2 ,2-dimethyl-2H-1-benzopyran (MA20B); ã 1-( 5,7-dimethoxy-2,2-dimethyl-2H-chromen-8-yl)-butan-1-one ... ã 8-[ 1-oxo-3(R)-ethoxy-butyl ]-5 ,7-dimethoxy-2, 2- dimethyl -2 H-1-benzopyran (MA20A); ã 8-[ 1-oxo-3(R)-propoxy-butyl ]-5 ,7-dimethoxy-2, 2- dimethyl -2 H-1-benzopyran (MA20C); ã 8-[ 1-oxo-3(R)-isopropoxy-butyl ]-5 ,7-dimethoxy-...