Heterocyclic systems containing bridgehead nitrogen atoms. Part LXVIII. Reaction of 5-fluorobenzimidazolyl-2-thione with chloroacetic acid: studies of orientation of cyclization in the syntheses of 6-fluoro- and 7-fluorothiazolo[3,2-a]benzimidazol-3(2-H)-ones
作者:H.K. Pujari、B.R. Sharma、Rajender Dahiya、Sudhir Kumar、Yasouki Murakami、Masanobu Tani
DOI:10.1016/s0022-1139(00)81001-5
日期:1990.2
4-Fluoroaniline on successive acetylation, nitration and hydrolysis affords 4-fluoro-2-nitroaniline which on reduction with Raney nickel and hydrazine hydrate followed by treatment of the resulting diamine with carbon disulphide in situ gives 5-fluorobenzimidazolyl-2-thione. The thione on condensation with chloroacetic acid yields [(5-fluoro-2-benzimidazolyl)-thioe]acetic acid which on cyclization
连续乙酰化,硝化和水解后的4-氟苯胺得到4-氟-2-硝基苯胺,将其用阮内镍和水合肼还原,然后用二硫化碳原位处理所得的二胺,得到5-氟苯并咪唑基-2-硫酮。硫酮在与氯乙酸缩合后生成[(5-氟-2-苯并咪唑基)-硫代]乙酸,其在乙酸酐和吡啶的混合物中环化后提供两种异构体,即。6-氟-和7-氟噻唑[3,2-a]苯并咪唑-3(2H)-ones。硫酮与1,2-二溴乙烷的缩合得到对称双-(5-氟苯并咪唑-2-基-巯基)乙烷。通过1 H NMR光谱数据,使用两种不同方法对6-氟-和7-氟噻唑并[3,2-a]苯并咪唑-3(2H)-进行了结构分配。