NOVELTY - Synthesis of 1,3-di-(4-carbmethoxyphenyl)-(1H,3H)-pyrimidine-2,4-dione involves Chapman rearrangement of 2,4-di-(4-carbmethoxyphenoxy)-pyrimidine under microwave irradiation (900 watts) in 15 minutes.    USE - The methods are useful for synthesizing 1,3-di-(4-carbmethoxyphenyl)-(1H,3H)-pyrimidine-2,4-dione; 1,3-di-(2-carbethoxyphenyl)-(1H,3H)-pyrimidine-2,4-dione; 1,3-diphenyl-(1H,3H)-pyrimidine-2,4-dione; 1,3-di-(1-naphthyl)-(1H,3H)-pyrimidine-2,4-dione; 1,3-di-(4-carbethoxy-2,6-dimethoxy phenyl)-(1H,3H)-pyrimidine-2,4-dione; 1,3-di-(2-ethoxyphenyl)-(1H,3H)-pyrimidine-2,4-dione; 1,3-di-(4-ethoxyphenyl)-(1H,3H)-pyrimidine-2,4-dione; 1,3-di-(4-chloro-3,5-dimethylphenyl)-(1H,3H)-pyrimidine-2,4-dione; and 1,3-di-(2-methylphenyl)-(1H,3H)-pyrimidine-2,4-dione (all claimed). The pyrimidinedione derivatives are used for treating or preventing metabolic disorders, neurological disorders, hematological diseases, cancer, inflammation, respiratory diseases, gastroenterological diseases, diabetic complications, an obesity-related disorders and non-alcoholic fatty liver diseases.    ADVANTAGE - Preferably, 2,4-diaryloxy pyrimidines of formulae (3a-3i) underwent facile Chapman rearrangement to afford 1,3-diarylpyrimidine-2,4-diones of formulae (4a-4i) under microwave irradiation which provides a simpler and environmental-friendly procedure under green chemistry conditions having promising future in industries (claimed). The methods can synthesize 1,3-diarylpyrimidine-2,4-diones having few steps of reactions, less reaction time, minimum use of solvents, clean work up, and better reaction yield.    DETAILED DESCRIPTION - Synthesis of 1,3-di-(4-carbmethoxyphenyl)-(1H,3H)-pyrimidine-2,4-dione of formula (4a) involves Chapman rearrangement of 2,4-di-(4-carbmethoxyphenoxy)-pyrimidine of formula (3a) under microwave irradiation (900 watts) in 15 minutes. INDEPENDENT CLAIMS are included for:    (1) a method for synthesis of 1,3-di-(2-carbethoxyphenyl)-(1H,3H)-pyrimidine-2,4-dione of formula (4b) which involves Chapman rearrangement of 2,4-di-(2-carbethoxyphenoxy)-pyrimidine of formula (3b) under microwave irradiation (900 watts) in 13 minutes;    (2) a method for synthesis of 1,3-diphenyl-(1H,3H)-pyrimidine-2,4-dione of formula (4c) which involves Chapman rearrangement of 2,4-diphenoxypyrimidine of formula (3c) under microwave irradiation (900 watts) in 12 minutes;    (3) a method for synthesis of 1,3-di-(1-naphthyl)-(1H,3H)-pyrimidine-2,4-dione of formula (4d) which involves Chapman rearrangement of 2,4-di-(1-naphthoxy)-pyrimidine of formula (3d) under microwave irradiation (900 watts) in 13 minutes;    (4) a method for synthesis of 1,3-di-(4-carbethoxy-2,6-dimethoxy phenyl)-(1H,3H)-pyrimidine-2,4-dione of formula (4e) which involves Chapman rearrangement of 2, 4-di-(4-carbethoxy-2, 6-dimethoxyphenoxy)-pyrimidine of formula (3e) under microwave irradiation (900 watts) in 18 minutes;    (5) a method for synthesis of 1,3-di-(2-ethoxyphenyl)-(1H,3H)-pyrimidine-2,4-dione of formula (4f) which involves Chapman rearrangement of 2,4-di-(2-ethoxyphenoxy)-pyrimidine of formula (3f) under microwave irradiation (900 watts) in 15 minutes;    (6) a method for synthesis of 1,3-di-(4-ethoxyphenyl)-(1H,3H)-pyrimidine-2,4-dione of formula (4g) which involves Chapman rearrangement of 2,4-di-(4-ethoxyphenoxy)-pyrimidine of formula (3g) under microwave irradiation (900 watts) m 13 minutes;    (7) a method for synthesis of 1,3-di-(4-chloro-3,5-dimethylphenyl)-(1H,3H)-pyrimidine-2,4-dione of formula (4h) which involves Chapman rearrangement of 2,4-di-(4-chloro-3,5-dimethylphenoxy)-pyrimidine of formula (3h) under microwave irradiation (900 watts) in 15 minutes; and    (8) a method for synthesis of 1,3-di-(2-methylphenyl)-(1H,3H)-pyrimidine-2,4-dione of formula (4i) which involves Chapman rearrangement of 2,4-di-(2-methylphenoxy)-pyrimidine of formula (3i) under microwave irradiation (900 watts) in 15 minutes.