Abstract: Disclosed are a novel, high-yield method for preparing entecavir and intermediates used therein.

Abstract: The present invention relates to a novel, high-yield and low-cost method for preparing entecavir, [1-S-(1?,3?,4?)]-2-amino-1,9-dihydro-9-[4-hydroxy-3-(hydroxymethyl)-2-methylenecyclopentyl]-6H-purin-6-one, an antiviral agent, and novel intermediates used therein.

Abstract: Disclosed are a novel, high-yield method for preparing entecavir and intermediates used therein.

Abstract: The present invention relates to a method for preparing capecitabine and a method for preparing a ?-anomer-rich trialkyl carbonate compound used therein, and a highly pure capecitabine can be efficiently prepared with a high yield by the method of the present invention using the ?-anomer-rich trialkyl carbonate compound as an intermediate.

Abstract: The present invention relates to a novel, high-yield and low-cost method for preparing entecavir, [1-S-(1?,3?,4?)]-2-amino-1,9-dihydro-9-[4-hydroxy-3-(hydroxymethyl)-2-methylenecyclopentyl]-6H-purin-6-one, an antiviral agent, and novel intermediates used therein.

Abstract: 1-?-halo-2,2-difluoro-2-deoxy-D-ribofuranose derivative of formula (I) having the 3-hydroxy group protected with a biphenylcarbonyl group is a solid which can be easily purified by a simple procedure such as recrystallization, and therefore, it can be advantageously used as an intermediate in the preparation of gemcitabine in a large scale. Further, the 1-?-halo-2,2-difluoro-2-deoxy-D-ribofuranose derivative of formula (I) can be prepared with high stereoselectivity using the compound of formula (V) as an intermediate.

Abstract: The present invention relates to a method for preparing capecitabine and a method for preparing a ?-anomer-rich trialkyl carbonate compound used therein, and a highly pure capecitabine can be efficiently prepared with a high yield by the method of the present invention using the ?-anomer-rich trialkyl carbonate compound as an intermediate.

Abstract: Provided is an improved method for stereoselectively preparing 2?-deoxy-2?,2?-difluorocytidine of formula (I), which includes reacting a 1-halo ribofuranose compound with a nucleobase of formula (IV) in a solvent to obtain a nucleo side of formula (II) with removal of a silyl halide ((alkyl)3SiX (X=halide)); and deprotecting the nucleoside of formula (II) to obtain 2?-deoxy-2?,2?-difluorocytidine of formula (I). 2?-Deoxy-2?,2?-difluorocytidine of formula (I) is effective for treating various cancers such as non-small cell lung (NSCLC), pancreatic, bladder, breast or ovarian cancers.

Abstract: 3R-carboxylate enantiomer derivative of formula (III) can be prepared easily and selectively by the method of the present invention, and a highly pure D-erythro-2,2-difluoro-2-deoxy-1-oxoribose derivative can be prepared efficiently from the compound of formula (III) as an intermediate.

Abstract: 3R-carboxylate enantiomer derivative of formula (III) can be prepared easily and selectively by the method of the present invention, and a highly pure D-erythro-2,2-difluoro-2-deoxy-1-oxoribose derivative can be prepared efficiently from the compound of formula (III) as an intermediate.

Abstract: This invention relates to an improved method for stereoselectively preparing 2¢¥-deoxy-2¢¥,2¢¥-difluorocytidine of formula (I), which comprises the steps of reacting a 1-halo ribofuranose compound of formula (III) with a nucleobase of formula (IV) in a solvent to obtain a nucleoside of formula (II) with removing the silyl halide of formula (V) produced during the reaction; and deprotecting the nucleoside of formula (II) to obtain 2¢¥-deoxy-2¢¥,2¢¥-difluorocytidine of formula (I).

Abstract: High purity cefdinir is prepared in a high yield by a process comprising the steps of: treating a crystalline salt of a cefdinir intermediate with a formic acid-sulfuric acid mixture or a formic acid-methanesulfonic acid mixture to obtain a crystalline salt of cefdinir and reacting the crystalline salt with a base in a solvent.

Abstract: A 3-(Z)-propenyl cephem compound is selectively prepared by reacting a phosphoranylidene cephem compound with acetaldehyde in the presence of a base in a solvent mixture comprising diethyl ether, formula (I), wherein R is a carboxyl protecting group; R1 is hydrogen or R2CH2CO—; and R2 is ethyl, 2-thiophenyl, phenyl, p-hydroxyphenyl or phenoxy

Abstract: This invention relates to a method for selectively preparing the 3-oxo-4-aza-5¥á-androstane compound which is used as an intermediate of finasteride by heating 3-oxo-4-aza-5-androstene in a mixture of formic acid and an alkanediol in the presence of zinc.

Abstract: This invention relates to a method for selectively preparing the 3-oxo-4-aza-5¥á-androstane compound which is used as an intermediate of finasteride by heating 3-oxo-4-aza-5-androstene in a mixture of formic acid and an alkanediol in the presence of zinc.

Abstract: The present invention relates to a pharmaceutical composition for treating or preventing obesity, comprising novel crystalline sibutramine methanesulfonate hemihydrate of formula (I).

Abstract: High purity cefdinir is prepared in a high yield by a process comprising the steps of: treating a cefdinir intermediate with a formic acid-sulfuric acid mixture or a formic acid-methanesulfonic acid mixture to obtain a crystalline salt of cefdinir and reacting the crystalline salt with a base in a solvent.

Abstract: A 3-(Z)-propenyl cephem compound is selectively prepared by reacting a phosphoranylidene cephem compound with acetaldehyde in the presence of a base in a solvent mixture comprising diethyl ether, formula (I), wherein R is a carboxyl protecting group; R1 is hydrogen or R2CH2CO—; and R2 is ethyl, 2-thiophenyl, phenyl, p-hydroxyphenyl or phenoxy.

Abstract: The present invention relates to a pharmaceutical composition for treating or preventing obesity, comprising novel crystalline sibutramine methanesulfonate hemihydrate of formula (I). The crystalline sibutramine methanesulfonate hemihydrate according to the present invention has a much higher solubility in water, and enhanced stability under a high humidity/temperature condition, as compared with sibutramine hydrochloride monohydrate.

Abstract: Highly pure cefpodoxime proxetil can be prepared by a simple process comprising the step of reacting a cefpodoxime salt with 1-iodoethylisopropylcarbonate in an organic solvent in the presence of a crown ether.