AIM:To simplify the procedure for synthesis of 2′ acetyl 12 hydroxy 2,3,10,11 dianhydro 6 O methyl erythromycin A(7). METHOD:Selective removal of the cladinose residue of clarithromycin was accomplished by the treatm...AIM:To simplify the procedure for synthesis of 2′ acetyl 12 hydroxy 2,3,10,11 dianhydro 6 O methyl erythromycin A(7). METHOD:Selective removal of the cladinose residue of clarithromycin was accomplished by the treatment with aqueous HCl at room temperature. Acetylation with acetic anhydride/triethylamine in methylene chloride provided the 2′ protected macrolide(9) with high yield. Then 2′ acetyl 12 hydroxy 2,3,10,11 dianhydro 6 O methyl erythromycin A(7) was synthesized from 9 which was treated with excess p toluenesulfonic acid and triethyl orthoformate at 50 ℃ in acetone.RESULT:The overall yield was 27%. The structure of the product was confirmed by IR,MS,NMR and elemental analysis. CONCLUSION: Our synthetic procedure of 7 was shorter and more convenient than that reported by Abbott Laboratories.展开更多
In this paper, it was found that isopropylidene (1-hydroxy-3-oxo-butylidene) malonate 4 was a heat unstable compound and the one step convenient methods for preparation of 4-hydroxy-6-methyl-2-pyrone 1 and 3-carboxy-4...In this paper, it was found that isopropylidene (1-hydroxy-3-oxo-butylidene) malonate 4 was a heat unstable compound and the one step convenient methods for preparation of 4-hydroxy-6-methyl-2-pyrone 1 and 3-carboxy-4-hydroxy-6-methyl-2-pyrone 2 in good yields were reported. Isopropylidene malonate 3、diketen and triethylamine reacted in chloroform to give 2, and in the mixture of dichloromethane and chlorobenzene to offer 1.展开更多
文摘AIM:To simplify the procedure for synthesis of 2′ acetyl 12 hydroxy 2,3,10,11 dianhydro 6 O methyl erythromycin A(7). METHOD:Selective removal of the cladinose residue of clarithromycin was accomplished by the treatment with aqueous HCl at room temperature. Acetylation with acetic anhydride/triethylamine in methylene chloride provided the 2′ protected macrolide(9) with high yield. Then 2′ acetyl 12 hydroxy 2,3,10,11 dianhydro 6 O methyl erythromycin A(7) was synthesized from 9 which was treated with excess p toluenesulfonic acid and triethyl orthoformate at 50 ℃ in acetone.RESULT:The overall yield was 27%. The structure of the product was confirmed by IR,MS,NMR and elemental analysis. CONCLUSION: Our synthetic procedure of 7 was shorter and more convenient than that reported by Abbott Laboratories.
文摘In this paper, it was found that isopropylidene (1-hydroxy-3-oxo-butylidene) malonate 4 was a heat unstable compound and the one step convenient methods for preparation of 4-hydroxy-6-methyl-2-pyrone 1 and 3-carboxy-4-hydroxy-6-methyl-2-pyrone 2 in good yields were reported. Isopropylidene malonate 3、diketen and triethylamine reacted in chloroform to give 2, and in the mixture of dichloromethane and chlorobenzene to offer 1.
