Abstract
Known methods of thiazole formation have been applied to the novel syntheses of indeno-(1':2'-4:5)-thiazole, and its 2-methyl-, 2-phenyl-, 2-amino-, and 2-hydroxy-derivatives, from 2-bromoindan-l-one. The synthesis of 2-mercaptoindenothiazole has been investigated. Attempts have been made to obtain 3'-substituted derivatives of the more stable indenothiazoles, and 3'-oxo-, 3' -hydroxy-, and 3'-benzylidene-2-phenylindeno-(1':2'-4:5)-thiazole and 3'-benzylideneindeno-(1:2'-4:5)-thiazole have been prepared. The direct route to the 3'-oxo-indenothiazoles from 2-bromoindan-1:3-dione has on investigation proved unsuccessful. The syntheses from 2-bromoindan-l-one of indeno-(1':2'-4:5)-oxazole and its 2-methyl derivative, and of 2-methylindeno-(1':2'-4:5)-imidazole, have failed, the reactions resulting in conversion into 2:2-dibromoindan-l-one. 3'-Oxoindeno-(1':2'-3:2)-thiophen has been prepared by modification of a reported procedure; on reduction the ketone has yielded 3'-hydroxyindeno-(1':2'-3:2)-thiophen. The 3'-oxo-, 3' -hydroxy-, and 3'-benzylidene -indeno-heterocycles mentioned have been subjected to the azido-reaction in order, primarily, to synthesise quinolino- and isoquinolino-heterocycles; (iso )quinolono-(4' :3' -3 :2 )-thiophen, 2-phenyl(iso )quinolono-(4':3 '-4:5)-thiazole, and 2-phenyl- (iso)quinolino-(4' :3' -4 :5 )-thiazole have been so prepared. (isp)Quinolonothiophen and 2-phenyl(iso)quinolono-thiazole have been degraded by Raney nickel desulphurisation to 4-ethyl(iso)carbostyril and 4-benzylamino(iso)carbostyril respectively; a record is included of attempts to establish the structures of these latter compounds. The mechanism of the azido-reacticn is discussed. Ring-expansion by rearrangement of fluorenone hydrazone has been attempted.