formula iv is firstly ester hydrolyzed and then cyclized in the presence of urea or in the presence of trifluoroacetamide 1 hydroxybenzotriazole hobt and n ethyl n u2032 3 dimethylamino propyl carbodiimide hydrochloride edci to yield the compound of formula i alternatively the compound of formula iv is firstly ammonolyzed and then reacts in the presence of condensing agent such as thionyl chloride dicyclohexylcarbodiimide dcc phosphorus oxychloride carbonyldiimidazole etc to yield the compound of formula i alternatively the compound of formula iv is firstly acylated converting hydroxyl to amino and then cyclized in alkaline condition such as in the presence of inorganic base for example potassium carbonate sodium carbonate etc or organic base for example potassium tert butoxide or sodium methoxide etc to yield the compound of formula i wherein each substituted group in the compounds of formula from i to iv mentioned above is defined as one of r r3 r4 and r5 is amino or protected amino carbamates such as carbobenzyloxy t butyloxycarbonyl fluorenylmethoxycarbonyl etc acyl amides such as acetyl phenylacetyl phthalyl etc azanes such as allyl etc sulfonyl and sulfinyl such as phenylsulfonyl p toluenesulfonyl phenylsulfiny o nitrophenylsulfinyl etc referred to greene t w and wuts p g m protective groups in organic synthesis p494 east china university of science and technology.