1-环丙基-6,7-二氟-1,4-二氢-8-羟基-4-氧代喹啉-3-羧酸乙酯的合成

1-环丙基-6,7-二氟-1,4-二氢-8-甲氧基-4-氧代喹啉-3-羧酸乙酯(2)经40%氢溴酸水解得到1-环丙基-6,7-二氟-1,4-二氢-8-羟基-4-氧代喹啉-3-羧酸(4),再在三甲基氯硅烷存在下经乙醇酯化得1-环丙基-6,7-二氟-1,4-二氢-8-羟基-4-氧代喹啉-3-羧酸乙酯(1),总收率为52.1%。也可用2在无水三氯化铝作用下水解直接得到1,收率66.9%。     

6,7-二氟-4-羟基-2-甲氧甲硫基-3-喹啉羧酸乙酯的合成

3,4-二氟苯胺在三乙胺存在下与二硫化碳生成芳基取代的二硫代氨基甲酸后与氯甲酸乙酯反应得到3,4-二氟苯基异硫氰酸酯,先后与由丙二酸二乙酯在无机碱中成的盐和氯甲基甲醚反应后加热环合,得到氟喹诺酮类抗菌剂普卢利沙星的中间体6,7-二氟-4-羟基-2-甲氧甲硫基-3-喹啉羧酸乙酯,总收率85.7%.     

普卢利沙星关键中间体的合成

3，4-二氟苯胺经一系列反应制得[（3，4-二氟苯胺基）（乙硫基）亚甲基]丙二酸二乙酯，再经闭环、羟基保护、氯代，最后脱保护、闭环得到普卢利沙星关键中间体6，7-二氟-1-甲基-4-氧代-1H，4H-[1，3]硫氮杂环丁烷并[3，2-α]喹啉-3-羧酸乙酯，总收率23％。     

1-乙基-1,4-二氢-7-硝基-4-氧-6-(1-哌嗪基)喹啉-3-羧酸的合成

氟哌酸(Norfloxacin,8)为吡酮酸类抗菌药物的优秀代表之一,由7-氯-1-乙基-6-氟-1,4-二氢-4-氧喹啉-3-羧酸同无水哌嗪缩合而得,由于氯、氟对亲核取代相竞争,在一般条件下有25％左右的氟被哌嗪取代了的副产物生成(J Med Chem 1980,23:1358)。基于芳香硝基对亲核试剂的敏感性高于氯(化学通报 1983,(5):38),我们设想把7-位氯改为硝基,即用1-乙基-1,4-二氢-7-硝基-4-氧-6-氟喹啉-3-羧酸乙酯(1)与无水哌嗪反应、有可能减少     

6,7-二氟-1-甲基-4-氧代-4H-[1,3]硫氮杂环丁烷并[3,2-α]喹啉-3-羧酸乙酯的合成工艺研究

目的：研究6，7-二氟-1-甲基-4-氧代-4H-[1，3]硫氮杂环丁烷并[3，2-α喹啉-3-羧酸乙酯的合成工艺改进方法。方法：以6，7-二氟-4-羟基-2-硫乙基-喹啉-3-羧酸乙酯为原料经乙酰化、氯代、环合步骤制备目标产物。结果：该方法工艺简单，后处理方便，且反应条件温和。结论：该合成路线易于工业化生产。     

3-氯-4-氟苯胺次甲丙二酸二乙酯的环化反应及氟哌酸异构体的合成

氟哌酸(Norfloxacin,13)是近年研制的吡酮酸类抗菌药物的优秀代表之一,7-氯-6- ??氟-4-羟基喹啉-3-羧酸乙酯(5a)是其重要中间体,系自3-氯-4-氟苯胺次甲丙二酸二乙酯(4a)在二苯醚中高温环化而得,工业生产有较大困难。曾有报道,苯胺次甲丙二酸二乙酯类使用Lewis酸作为环化剂,可在常温或稍高温度下进行环化。据此,我们首先使用多聚磷     

6-氟喹诺酮类衍生物的合成及抗菌活性

报道一系列7,8-双取代的1-环丙基和1-乙基-6-氟-1,4-二氢-4-氧-3-喹啉羧酸衍生物的合成和体外抗菌活性。其中,1-环丙基-6-氟-7-(4-乙酰氧基哌啶)-8-氯-1,4-氢-4-氧-3-喹啉羧酸(11c)和1-环丙基-6-氟-7-(4-羟基哌啶)-8-氯-1,4-二氢-4-氧-3-喹啉羧酸(11b)同环丙沙星相比有更强的体外活性,尤其对金黄色葡萄球菌、耐甲氧青霉素金葡菌(MRSA)和绿脓杆菌。     

碱和水份对7-氯-6-氟-4-羟基喹啉-3-羧酸乙酯的N-或O-乙基化产物比例的影响

7-氯-6-氟-4-羟基喹啉-3-羧酸乙酯(3)的乙基化使用无水 K_2CO_3或无水 Na_2CO_3作脱酸剂,用HPLC 法测定 N-及 O-乙基化物(2与1)的相对含量。考察了溶剂中水份对2和1生成比例的影响。     

莫西沙星8-二氟甲氧基类似物的合成与体内外抗菌作用

1-环丙基-6，7-二氟-8-甲氧基-1，4-二氢．4-氧代喹啉．3-羧酸乙酯依次经醚键断裂、酯化、二氟甲基醚化得1．环丙基-6，7-二氟-8-二氟甲氧基-1，4-二氢-4-氧代喹啉．3-羧酸乙酯，然后经过螫合、与[1S，6S]-2．叔丁氧羰基．2，8．二氮杂双环[4，3，0]壬烷缩合、最后脱除叔丁氧羰基保护得到1-环丙基．8．二氟甲氧基-7-[（1S，6S）．2，8．二氮杂双环[4，3，0]壬烷．8．基]-6-氟．1，4-二氢-4-氧代喹啉-3-羧酸。目标化合物的结构经核磁共振氢谱和质谱（ESI）所确证，并测定了其体内外抗菌作用，结果表明该化合物优于对照药环丙沙星，与莫西沙星相当或略优，尤其对肺炎链球菌29074的体内活性突出，值得深入评价。     

5-氨基-8-甲氧基-喹诺酮类的合成及其体外抗菌作用

以1-环丙基-6，7-二氟-8-甲氧基-1，4-二氢-4-氧代喹啉-3-羧酸乙酯为起始原料依次经过硝化、还原和水解三步反应制得5-氨基-1-环丙基-6，7-二氟-8-甲氧基-1，4-二氢-4-氧代喹啉-3-羧酸，然后分别与2（R）-（-）／2（S）-（＋）或2（R，S）-甲基哌嗪缩合，得到3种目标化合物（5a、5b和5c）。测定它们对20株临床分离和标准革兰阴性菌和标准革兰阳性菌的最低抑菌浓度。结果表明，5a和5b的体外抗菌活性与外消旋体5c基本相当。     

Antibacterial and antifungal agents. VI. Pirfloxacin and related compounds: synthetic and microbiological studies

A new route to pirfloxacin, a fluorinated pyrrylquinolone with high broad-spectrum antibacterial activities, is described starting from 7-amino-1-ethyl-6-fluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid and 2,5-dimethoxytetrahydrofuran. When the reaction with the latter compound was carried out using the ethyl ester of the above acid the related pyrryl ester formed, which on alkaline hydrolysis gave pirfloxacin. The synthesis and antibacterial activities of the 1-allyl analogue of pirfloxacin and of 7-[2-(1-pyrrolidinomethyl)-1-pyrryl]-1-ethyl-1, 4-dihydro-4-oxoquinoline-3-carboxylic acid and its 6-fluoroderivative are also reported.     

Synthesis and antibacterial activity of thiosemicarbazones of 3-acylquinolones]

Oxidation of 3-acetyl derivatives of 3-acetyl-1-ethyl-1,4-dihydro-6,7-methylenedioxyquinoline-4-one (VIc) and 3-acetyl-7-chloro-1-ethyl-6-fluoro-1,4-dihydroquinoline-4-one (VId) with selenium dioxide provided the corresponding acids, [1-ethyl-1,4-dihydro-6,7-methylenedioxy-4-oxoquinoline-3-yl]glyoxylic acid (VIe) and [7-chloro-1-ethyl-6-fluoro-1,4-dihydro-4-oxoquinoline-3-yl]glyoxylic acid (VIf), respectively. Reactions of compounds VIc--VIf with thiosemicarbazide yielded the respective thiosemicarbazones of 3-acetyl-1-ethyl-1,4-dihydro-6,7-methylenedioxyquinoline-4-one (VIIa), 3-acetyl-7-chloro-1-ethyl-6-fluoro-1,4-dihydroquinoline-4-one (VIIb), [1-ethyl-1,4-dihydro-6,7-methylenedioxy-4-oxoquinoline-3-yl]glyoxylic acids (VIId). The compounds showed no significant in vitro antibacterial activity.     

Synthesis and structure-activity relationships of new 7-[3-(fluoromethyl)piperazinyl]- and -(fluorohomopiperazinyl)quinolone antibacterials

Some novel 6-fluoro-7-substituted-1,4-dihydro-4-oxoquinoline-3-carboxylic acids have been prepared. At the N-1 position "standard" substitution was employed with the ethyl, cyclopropyl, and p-fluorophenyl groups being used. At C-7 the introduction of some novel piperazines was made. Most notably, 2-(fluoromethyl)piperazine (10) and hexahydro-6-fluoro-1H-1,4-diazepine (16, fluorohomopiperazine) at the quinolone C-7 position produced products with similar in vitro antibacterial activity as the ciprofloxacin reference. The in vivo efficacy of 1-cyclopropyl-6-fluoro-7-[3-(fluoromethyl)piperazinyl]-1,4-dihydro-4- oxoquinoline-3-carboxylic acid (20) was excellent with better oral absorption than ciprofloxacin (2).     

Pyridonecarboxylic acids as antibacterial agents. 4. Synthesis and antibacterial activity of 7-(3-amino-1-pyrrolidinyl)-1-ethyl-6-fluoro-1,4 -dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid and its analogues

The title compounds (28-56) with an amino- and/or hydroxy-substituted cyclic amino group at C-7 were prepared with 1-substituted 7-chloro-, 7-(ethylsulfonyl)-, and 7-(tosyloxy)-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3- carboxylic acids and their ethyl esters (3-7) with cyclic amines such as 3-aminopyrrolidine. The N-1 substituent includes ethyl, vinyl, and 2-fluoroethyl groups. As a result of in vitro and in vivo antibacterial screenings, three compounds, 1-ethyl- and 1-vinyl-7-(3-amino-1-pyrrolidinyl)-6-fluoro- 1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acids (33a and 33b) and 1-vinyl-7-[3-(methylamino)-1-pyrrolidinyl] analogue 34b, were found to be more active than enoxacin (2) and to be worthy of further biological study. Structure-activity relationships are discussed.     

Isolation and identification of metabolites of ofloxacin in rats, dogs and monkeys

Metabolites of (+/-)-9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-7H -pyrido [1,2,3-de][1,4]benzoxazine-6-carboxylic acid (ofloxacin) in excreta of rats, dogs and monkeys after oral administration of 14C-ofloxacin (20 mg/kg) were isolated and identified. Three metabolites of ofloxacin were detected in the excreta of all three species, and identified by t.l.c., u.v., n.m.r. and mass spectrometry as follows: M-1, ester glucuronide of ofloxacin; M-2, unchanged ofloxacin; M-3, (+/-)-9-fluoro-2,3-dihydro-3-methyl-10-(1-piperazinyl)-7-oxo-7H-pyrido [1,2,3-de][1,4]benzoxazine-6-carboxylic acid (desmethyl ofloxacin); M-4, (+/-)-9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-7H -pyrido [1,2,3-de][1,4]-benzoxazine-6-carboxylic acid piperazine-4-oxide (ofloxacin N-oxide). It is concluded that ofloxacin is metabolized by O-acyl glucuronidation, N-demethylation and N-oxidation.     

吡酮酸类抗菌药物的研究——Ⅵ.7-氯-6-氟-1-乙基-1,4-二氢-4-氧吡啶(2,3-c)并哒嗪-3-羧酸及其衍生物的合成与抗菌活性

由2,6-二氯-5-氟-3-氰基吡啶出发,经氰基水解、酰氯化、与重氮乙酸乙酯缩合、重氮基还原、环化五步反应合成了一个新的杂环体系,即取代的吡啶(2,3-c)并哒嗪Ⅵ。由Ⅵ为原料经不同途径制得21个新衍生物,其中10个游离酸进行了体外抗菌活性筛选。对金葡-15、大肠-1515、绿脓-29的MIC(μg/ml),除化合物Xa和Xb对大肠-1515为50外,其余均大于100。     

2-Oxo-1,8-naphthyridine-3-carboxylic acid derivatives with potent gastric antisecretory properties

The syntheses of 2-oxo-1,8-naphthyridine-3-carboxylic acid derivatives having potent gastric antisecretory properties in the pyloric-ligated (Shay) rat model are described. Two of the more potent compounds tested that were selected for more detailed dose-response evaluation were 4-amino-1-ethyl-1,2-dihydro-2-oxonaphthyridine-3-carboxylic acid ethyl ester (35) and 1-ethyl-1,2-dihydro-7-methyl-4-(4-methyl-1-piperazinyl)-2- oxo-1,8-naphthyridine-3-carboxylic acid ethyl ester (77). These compounds lowered total acid output in the rat in a dose-related fashion. Both compounds were more potent than cimetidine when tested in the rat. Both 35 and 77 showed inhibitory activity in food-stimulated acid secretion in the Pavlov-pouch, conscious dog. The mechanism of action for this series is not known. Details of structure-activity relationships are described.     

Isolation and identification of metabolites of ofloxacin in rats,dogs and monkeys

1. Metabolites of (±)-9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acid (ofloxacin) in excreta of rats, dogs and monkeys after oral administration of ¹⁴C-ofloxacin (20?mg/kg) were isolated and identified.

2. Three metabolites of ofloxacin were detected in the excreta of all three species, and identified by t.l.c., u.v., n.m.r. and mass spectrometry as follows: M-1, ester glucuronide of ofloxacin; M-2, unchanged ofloxacin; M-3, (±)-9-fluoro-2,3-dihydro-3-methyl-10-(1-piperazinyl)-7-oxo-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acid (desmethyl ofloxacin); M-4, (±)-9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-7H-pyrido[1,2,3-de][1,4]-benzoxazine-6-carboxylic acid piperazine-4-oxide (ofloxacin N-oxide).

3. It is concluded that ofloxacin is metabolized by O-acyl glucuronidation, N-demethylation and N-oxidation.     

Pyridonecarboxylic acids as antibacterial agents. 2. Synthesis and structure-activity relationships of 1,6,7-trisubstituted 1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acids, including enoxacin, a new antibacterial agent

The title compounds having nitro, amino, cyano, chloro, or fluoro as the C-6 substituent were prepared. Introduction of the chloro and cyano groups at C-6 was accomplished by the Sandmeyer reaction of 6-amino-1,8-naphthyridine derivatives 9 via their 6-diazonium salts. The reaction was extended to the synthesis of the 6-fluoro analogues, involving the Balz-Schiemann reaction of the diazonium tetrafluoroborate. Furthermore, a series of the 1-ethyl, 1-vinyl, 1-(2-fluoroethyl), and 1-(difluoromethyl) analogues of 7-substituted 6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acids was prepared. 1-Pyrrolidinyl and, particularly, N-substituted or unsubstituted 1-piperazinyl groups were introduced as the C-7 variants. As a result of this study, 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-1, 8-naphthyridine-3-carboxylic acid (named enoxacin, originally AT-2266) was found to show the most broad and potent in vitro antibacterial activity, an excellent in vivo efficacy on systemic infections, and a weak acute toxicity. Structure-activity relationships of compounds with variations of substituents at C-1, C-6, and C-7 are also discussed.