Process for the preparation of 6-aryl-4H-s-triazolo(4,3-a)(1,4)benzodiazepines
United States Patent 1 Sellstedt et al.  
 [451 Apr. 29, 1975 PROCESS FOR THE PREPARATION OF 6-ARYL-4H-S-TRIAZOLO( 4,3- A 1,4)BENZODIAZEPINES [75] Inventors: John H. Sellstedt, King of Prussia;  
 Daniel M. Teller, Devon, both of Pa.  
 [73] Assignee: American Home Products Corporation, New York, NY.  
  221 Filed: Nov. 3, 1972 211 App]. N0.Z 303,668  
 [52] US. Cl... 260/308 R; 260/296 T; 260/2564 R;  
  260/999 [51] Int. Cl C07d 99/02 [581 Field of Search 260/308 R [56] References Cited UNITED STATES PATENTS 3,767.660 l0/l973 Hester 260/308 Primary ExaminerHenry R. Jiles&#39; Assistant Examiner-Robert T. Bond Attorney, Agent, or FirmR0yal E. Bright 1 Claim, N0 Drawings PROCESS FOR THE PREPARATION OF 6-ARYL-4H-S-TRIAZOLO(4,3- A)(1,4)BENZODIAZEPINES BACKGROUND OF THE INVENTION 6-Phenyl-4H-s-triazolo[4,3-a][ l ,4 lbenzodiazepines have previously been reported by Hester, et al, in The Journal of Medicinal Chemistry, Vol. 14, p. 1078, (1971), as being prepared from l,3-dihydro--phenyl- 2H-1,4-benzodiazepine-2-thiones and carboxylic acid hydrazides.  
  The present invention provides an alternative synthesis for 6-aryl-4H-s-triazolo[4,3- a][ l,4]benzodiazepines.  
 SUMMARY OF THE INVENTION The invention sought to be patented in its principal process aspect resides in the concept of a process for the preparation of 6-aryl-4H-s-triazolo[4,3- a][l,4]benzodiazepine of the formula:  
 wherein R is hydrogen, lower alkyl, lower alkoxy, phenyl, lower alkoxyphenyl, phenyl(lower)alkyl, heteroaryl, halo, trifluoromethyl, nitro, di(lower)alkylamino, carbalkoxy, lower alkyl thio, lower alkyl sulfonyl, lower alkyl sulphinyl, or cyano; R is hydrogen, lower alkyl, lower alkoxy, phenyl, lower alkoxyphenyl, phenyl(lower)alkyl, heteroaryl, halo, trifluoromethyl, nitro, di(- lower)alkylamino, carbalkoxy, lower alkyl thio, lower alkyl sulfonyl, lower alkyl sulphinyl, or cyano; R is hydrogen, lower alkyl, lower alkoxy, phenyl, lower alkoxyphenyl, phenyl(lower)alkyl, heteroaryl, halo, trifluoromethyl, nitro, di(lower)alkylamino, carbalkoxy, lower alkyl thio, lower alkyl sulfonyl, lower alkyl sulphinyl, or cyano, with the proviso that R and R are not adjacent trifluoromethyl; R is hydrogen, lower alkyl, lower alkoxy, low&#39;er acyloxy, or halo; R is hydrogen, lower alkyl, lower alkoxy, lower alkoxyphenyl, heteroaryl, phenyl(lower)alkyl, di(lower)alkylamino, carbalkoxy, or trifluoromethyl; which comprises warming in the presence of a hydrogen halide absorber, a 2- halo-5-aryl-3l-l-l ,4-benzodiazepine of the formula:  
 wherein R, R, R and R are as defined hereinabove, and X is halo with a tetrazole of the formula:  
  N-Nll 11 wherein R is as defined hereinabove.  
  The tangible embodiments produced by the principal process aspect of the invention possess the inherent general physical properties of being crystalline solids, being substantially insoluble in water, and generally soluble in such common organic solvents as chloroform, dichloromethane, acetone, ethyl acetate and the like.  
  Examination of the product produced by the aforesaid process reveals, upon infrared and nuclear magnetic resonance spectrographic analysis, spectral data supporting the molecular structure hereinbefore set forth.  
  The tangible embodiments produced by the principle process aspect of the invention possess the inherent applied use characteristics of exerting CNS depressant activity while having low toxicity in experimental animals as evidenced by pharmacological evaluation according to standard test procedures.  
  The invention sought &#34;to be patented in a subgeneric process aspect is described as residing in the concept of a process for the preparation of 6-aryl-4H-striazolo[4,3-a][ l,4]benzodiazepines of the formula:  
 wherein R is hydrogen,- halo, trifluoromethyl, nitro, or thiomethyl; R is hydrogen, or halo; R is hydrogen or halo; R is hydrogen, lower alkyl, lower alkoxy, lower acyloxy, or halo; and R is hydrogen, lower alkyl, or lower alkoxyphenyl; which comprises warming, in the presence of a hydrogen halide acceptor, a 2-halo-5- aryl-3H-l,4-benzodiazepine of the formula:  
 wherein R, R, R and R are as described immediately hereinabove, and X is halo; with a tetrazole of the formula:  
 wherein R is as defined immediately hereinabove.  
 DESCRIPTION OF THE PREFERRED EMBODIMENT be necessary to initiate and maintain reaction. The exact temperature is not particularly critical and a range of about 80 to about 180 is suitable. Normally for convenience the reaction is conducted at the reflux temperature of the solvent employed. The time required for the reaction is not critical but normally nitrogen evolution during the course of the reaction will be observed, and continued heating for a few minutes after this evolution ceases will be sufficient.  
  While the process has been specifically illustrated with reference to figure A which describes the preparation of 8-chloro-7-(o-chlorophenyl)-4-methoxy-lmethyl-4H-s-triazol0[4,3-a][ l,4]benzodiazepine, it will be obvious to the skilled organic chemist to substitute any of the various substituted starting materials, and obtain the various 6-aryl-4H-s-triazolo[4,3- a][l,4]benzodiazepines contemplated to be prepared by the invention.  
  Starting materials for the practice of the invention, namely the aforementioned 2-halo-5-aryl-3H-l ,4-  
 Figure A Cl N /N-NH Il-/C-OMe Me-(/\ Cl C I N N:N  
 \ ll C H C OMe Cl CIN III In addition to pyridine, the reaction solvent and hy- 60 benzodiazepines may be prepared by treatment of the corresponding 5-aryl-3I-I- l ,4-benzodiazepine-2-ones with a halogenating agent as described in the copending Sellstedt application Ser. No. 293,701 filed September 29, 1972. The preparation of 5-aryl-3H-l,4- benzodiazepin-Z-ones is described in the article The Chemistry of Benzodiazepines by Giles A. Archer and Leo I-l. Sternbach in Chemical Reviews, Volume 68, page 747 (1968), and the references cited therein. The  
 other necessary starting materials for the practice of the invention namely the S-substituted tetrazoles are compounds either commercially available or obtainable by synthetic methods we11-known in the chemical literature.  
  6-aryl-4H-s-triazolo[4,3-a][1,4]benzodiazepines, the tangible embodiments produced by the present invention are useful as CNS depressant agents as reported by Hester, et al., in The Journal of Medicinal Chemistry, Volume 14, page 1073, (1971).  
  As used herein the term lower alkyl means a saturated hydrocarbon radical including the straight and branched chain radicals of from one to six carbon atoms, among which are for the purposes of illustration, but without limiting the generality of the foregoing, methyl, ethyl and i-butyl. The term heteroaryl&#34; means an aromatic heterocyclyl radical containing from three to five carbon atoms, and one or more atoms selected from the group nitrogen, oxygen, and sulfur, among which are for the purposes of illustration, but without limiting the generality of the foregoing, 2- pyridyl, and Z-pyrimidinyl. The term halo means fluoro, chloro, or bromo.  
  The following examples further illustrate the best mode contemplated by the inventors for carrying out the invention.  
 EXAMPLE I 8-Chloro-6-(o-Chlorophenyl)-4-Methoxy-1-(p- Methoxyphenyl)-4H-s-Triazolo[4,3- a][ 1,4]Benzodiazepine 5-(p-Methoxyphenyl)tetrazole (2.90 g., 0.0165 mole) is dissolved in 33 ml. of pyridine, and 2,7- dichloro-5-(o-chlorophenyl)-3-methoxy-3H-1,4- benzodiazepine (3.54 g., 0.01 mole) is added all at once. The solution is stirred and the mixture brought to reflux. At reflux nitrogen is rapidly evolved, and heating is continued for two minutes after evolution stops.  
 The solution is cooled and poured into 300 ml. of water. The mixture is filtered and the residue washed with water, giving a brown solid. The solid is recrystallized from ethyl acetate with charcoal, giving 1.30 g. of buff colored crystals, m.p. 238240.  
 Analysis for: C H Cl N O Calculated: C, 61.94; H, 3.89; N, 12.04; Cl, 15.24  
 Found: C, 61.80; H, 3.94; N, 12.15; Cl, 15.11.  
 EXAMPLE ll 8-Chloro-6-(o-Chlorophenyl)-4-Methoxy-l-Methyl- 4H-s-Triazolo[4,3-a][1,4]Benzodiazepine S-Methyltetrazole (3.54 g., 0.0422 mole) is dissolved in ml. of pyridine, and 2,7-dichloro-5-(ochlorophenyl)-3-methoxy-3H-1,4-benzodiazepine (9.70 g., 0.0274 mole) is added all at once. The solution is stirred and the mixture is brought to reflux. At  
 reflux nitrogen is rapidly evolved, and heating is continued for 3 minutes after nitrogen evolution stops. The solution is cooled and most of the pyridine is removed at 60 in vacuo. The residue is poured into 500 m1. water, and the mixture is filtered giving 8.65 g. of a tan solid. The solid is recrystallized from acetonitrile with charcoal, giving 3.10 g. ofa pink solid, mp. 250252.  
 Analysis for: C H Cl N O Calculated: C, 57.93; H, 3.78; N, 15.01; Cl, 19.00 Found: C, 57.90; H, 3.77; N, 15.26; Cl, 19.15.