The alkylation of 2-amino-5-chloro-2'-fluorobenzophenone (II) with 2,2,2-trifluoroethyl trichloromethylsulfonate (A) gives 2-(2,2,2-trifluoroethylamino)-5-chloro-2'-fluorobenzophenone (III), which is bromoacetylated with bromoacetyl chloride (B) in refluxing benzene yielding the bromoacetanilide (IV).This compound is cyclized with NH3 in chloroform affording 7-chloro-1-(2,2,2-trifluoroethyl)-1,3-dihydro-5-(2-fluorophenyl)-2H-1,4-benzodiazepin-2-one (I), which by reaction with P2S5 in refluxing dioxane gives the target compound.
The alkylation of p-chloroaniline (V) as before yields N-(2,2,2-trifluoroethyl)aniline (VI), which is then condensed with aziridine (C) affording the substituted aniline (VII). The benzoylation of (VII) with 2-fluorobenzoyl chloride (D) yields the amide (VIII), which is cyclized with P2O5 in refluxing POCl3 giving 7-chloro-(2,2,2-trifluoroethyl)-1,3-dihydro-2H-5-(2-fluorophenyl)-1,4-benzodiazepine (IX). This compound is oxidized with RuO4 in CCl4 to give 7-chloro-1-(2,2,2-trifluoroethyl)-1,3-dihydro-5-(2-fluorophenyl)-2H-1,4-benzodiazepin-2-one (I), which by reaction with P2S5 in refluxing dioxane gives the target compound.
1) The alkylation of 2-amino-5-chlorobenzophenone (I) with 2,2,2-trifluoroethyl trichloromethansulfonate (II) in refluxing xylene gives the N-trifluoroethyl derivative (III), which is then cyclized with glycine ethyl ester (A) in refluxing pyridine. 2) Compound (III) can also be bromoacetylated with bromoacetyl bromide (B) in refluxing benzene yielding the N-bromoacetyl compound (IV), which is then cyclized with ammonia in CHCl3. 3) By alkylation of 7-chloro-5-phenyl-1,3-dihydro-2H-1,4-benzodiazepin-2-one (IX) with NaOMe and 2,2,2-trifluoroethyl iodide in MeOH.
The reaction of 4-chloro-N-(2,2,2-trifluoroethyl)aniline (V) with ethyleneimine (C) by means of AlCl3 in benzene affords the N-(2-aminoethyl) compound (VI), which is benzoylated with benzoyl chloride (D) as usual yielding the benzamide (VII). Compound (VII) is cyclized with P2O5 in POCl3 giving 7-chloro-1,2-dihydro-5-phenyl-1-(2,2,2-trifluoroethyl)-3H-1,4-benzodiazepine (VIII), which is finally oxidized with RuO4.
N-trifluoroethyl derivative (III) can also be obtained by alkylation of (X) with (II) in refluxing xylene giving 4-chloro-N-(2,2,2-trifluoroethyl)aniline (XV), followed by a Friedel-Crafts reaction with benzoyl chloride by means of AlCl3.
N-bromoacetyl compound (IV) can also be obtained by bromoacetylation of (XV) with bromoacetyl bromide (B) in refluxing benzene affording 4-chloro-N-bromoacetyl-N-(2,2,2-trifluoroethyl)aniline (XVI), followed by a Friedel-Crafts reaction with benzoyl chloride by means of AlCl3.
The starting benzophenone (I) can also be obtained in several different ways: a) By a Friedel-Crafts reaction of p-chloroaniline (X) and benzoyl chloride (D). b) By reaction of 5-chloroanthranilic acid (XI) with acetic anhydride to the bicyclic compound (XII), which is then submitted to a Grignard reaction with phenylmagnesium bromide (E). c) By oxidation of 2,3-diphenyl-5-chloroindole (XIII) with CrO3 to the N-benzoylbenzophenone (XIV), followed by debenzoylation with NaOH.