Zaslat záznam emailem: Crystal structures of butyl 2-amino-5-hy­droxy-4-(4-nitro­phen­yl)benzo­furan-3-carboxyl­ate and 2-meth­oxy­ethyl 2-amino-5-hy­droxy-4-(4-nitro­phen­yl)benzo­furan-3-carboxyl­ate