会员体验
专利管家(专利管理)
工作空间(专利管理)
风险监控(情报监控)
数据分析(专利分析)
侵权分析(诉讼无效)
联系我们
交流群
官方交流:
QQ群: 891211   
微信请扫码    >>>
现在联系顾问~
热词
    • 8. 发明授权
    • Asymmetric process for preparing florfenicol, thiamphenicol
chloramphenicol and oxazoline intermediates
    • 制备氟苯尼考,甲砜霉素氯霉素和恶唑啉中间体的不对称方法
    • US5352832A
    • 1994-10-04
    • US993932
    • 1992-12-18
    • Guang-Zhong WuWanda I. Tormos
    • Guang-Zhong WuWanda I. Tormos
    • C07D303/08A61K31/165C07B53/00C07C231/02C07C233/18C07C233/25C07C315/04C07C317/32C07D263/14C07D301/19C07D303/34C07C233/05C07C233/12C07D263/08
    • C07C315/04C07B2200/07Y02P20/582
    • The present invention comprises a process for the asymmetric synthesis of florfenicol, thiamphenicol or chloramphenicol, from a derivative of trans-cinnamic acid, comprising the steps:(a) converting the acid to an acid chloride using a chlorinating agent, and reducing the acid chloride to a trans allylic alcohol with a reducing agent;(b) asymmetrically epoxidizing the allylic alcohol of step (a), by reacting with t-butylhydroperoxide in the presence of a chiral epoxidation catalyst prepared from titanium (IV) isopropoxide and L-diisopropyltartaric acid, to form a chiral epoxide;(c) regioselectively opening the epoxide of step (b) by sequentially treating with sodium hydride, zinc chloride and dichloroacetonitrile to form an oxazoline;(d) stereoselective inversion/isomerization of the oxazoline of step (c) by sequentially treating with: (i) a lower alkylsulfonyl chloride and a tertiary amine base; (ii) sulfuric acid and water; (iii) an alkali metal hydroxide; to form an oxazoline;(e) optionally treating the oxazoline of step (d) with a fluorinating agent, for preparing florfenicol, then hydrolyzing with acid.In an alternative embodiment, the present invention comprises a process for isomerizing of the S,S-isomer of florfenicol to the R,S-isomer (I) by sequentially treating with: (i) a lower alkylsulfonyl chloride and a tertiary amine base; (ii) sulfuric acid and water; (iii) an alkali metal hydroxide.The present invention further comprises a process for regioselectively opening an epoxide to form a threo-oxazoline.
    • 本发明包括由反式肉桂酸衍生物不对称合成氟苯尼考,甲砜霉素或氯霉素的方法,包括以下步骤:(a)使用氯化剂将酸转化为酰氯,并将酰氯还原 与还原剂的反式烯丙醇; (b)通过与叔丁基过氧化氢在由异丙醇钛(Ⅳ)和L-二异丙基酒石酸制备的手性环氧化催化剂存在下反应形成手性环氧化物,使步骤(a)的烯丙醇不对称环氧化; (c)通过依次用氢化钠,氯化锌和二氯乙腈处理以形成恶唑啉,选择性地打开步骤(b)的环氧化物; (d)通过以下步骤依次处理步骤(c)的恶唑啉的立体选择性反转/异构化:(i)低级烷基磺酰氯和叔胺碱; (ii)硫酸和水; (iii)碱金属氢氧化物; 形成恶唑啉; (e)任选用氟化剂处理步骤(d)的恶唑啉,制备氟苯尼考,然后用酸水解。 在一个替代实施方案中,本发明包括通过以下步骤:(i)低级烷基磺酰氯和叔胺碱使氟苯尼考的​​S,S-异构体异构化成R,S-异构体(I)的方法。 (ii)硫酸和水; (iii)碱金属氢氧化物。 本发明还包括区域选择性地打开环氧化物以形成苏氨恶唑啉的方法。