scheme 1 below illustrates a specific example of the present invention whereby the aryl fused azapolycyclic compound of formula i is prepared in high purity and yield . prior attempts , as disclosed in u . s . pat . no . 6 , 410 , 550 , to convert the compounds of formula vii into the compound of formula v utilized either 40 % aqueous glyoxal or the addition adduct of sodium bisulfite and ethane dione . both of these reactions required certain purification steps . the present inventors have discovered , quite surprisingly , that the overall purity of the final product obtained from the sequence of steps illustrated in scheme 1 can be significantly increased by incorporating the new reaction conditions and procedures described herein below . additional examples of selected reaction conditions employed in the present invention which provide increased overall purity of the final product obtained according to scheme 1 include : 1 . dilution of 40 % aqueous glyoxal to a concentration of from about 5 % to about 20 % in scheme 1 . 2 . maintaining a ph above 7 in the cyclization step through the addition of a buffering agent . 3 . a reaction temperature in scheme 1 selected from the range of from about − 10 ° c . to about 20 ° c . 4 . effective removal of hydrogenation catalyst by filtration prior to cyclization in step in scheme 1 . as illustrated in scheme 2 below , compounds of formula vii are precursors to the aryl fused azapolycyclic compound of formula i and its pharmaceutically acceptable acid salts . preferably the acid salt is the l - tartaric acid salt . the compound of formula i is useful in the treatment of central nervous system disorders as described herein . removal of the nitrogen protecting group q is carried out by methods well known in the art , such as , heating with base in a solvent mixture of water and a water immiscible organic solvent including , for example , toluene or methylene chloride . most preferably , the base is sodium hydroxide and the organic solvent is toluene . optionally , colored impurities are removed by treating a methanolic solution of vii with activated carbon . in the practice of the present invention according to scheme 1 , a compound of formula viii is formed . without being bound to a particular theory , it is believed that the formation of viii is minimized by avoiding side reactions in step 2 of scheme 1 . thus , isopropyl alcohol is preferred over methanol . furthermore , certain forms of carbon should be avoided . examples of undesirable forms of carbon include but are not limited to carbon supports used in hydrogenation catalysts and activated carbon normally used as a purification and decolorizing agent . compounds of formula i and its pharmaceutically acceptable salts bind to neuronal nicotinic acetylcholine specific receptor sites and are useful in modulating cholinergic function . such compounds are useful in the treatment of inflammatory bowel disease ( including but not limited to ulcerative colitis , pyoderma gangrenosum and crohn &# 39 ; s disease ), irritable bowel syndrome , spastic dystonia , chronic pain , acute pain , celiac sprue , pouchitis , vasoconstriction , anxiety , panic disorder , depression , bipolar disorder , autism , sleep disorders , jet lag , amyotrophic lateral sclerosis ( als ), cognitive dysfunction , hypertension , bulimia , anorexia , obesity , cardiac arrythmias , gastric acid hypersecretion , ulcers , pheochromocytoma , progressive supranuclear palsy , chemical dependencies and addictions ( e . g ., dependencies on , or addictions to nicotine ( and / or tobacco products ), alcohol , benzodiazepines , barbiturates , opioids or cocaine ), headache , migraine , stroke , traumatic brain injury ( tbi ), obsessive - compulsive disorder ( ocd ), psychosis , huntington &# 39 ; s chorea , tardive dyskinesia , hyperkinesia , dyslexia , schizophrenia , multi - infarct dementia , age - related cognitive decline , epilepsy , including petit mal absence epilepsy , senile dementia of the alzheimer &# 39 ; s type ( ad ), parkinson &# 39 ; s disease ( pd ), attention deficit hyperactivity disorder ( adhd ) and tourette &# 39 ; s syndrome . the following examples are provided for the purpose of further illustration and are not intended to limit the scope of the claimed invention . cyclization of 2 , 3 , 4 , 5 - tetrahydro - 3 -( trifluoroacetyl )- 1 , 5 - methano - 1h - 3 - benzazepine - 7 , 8 - diamine ( compound vi ) with glyoxal to form 7 , 8 , 9 , 10 - tetrahydro - 8 -( trifluoroacetyl )- 6 , 10 - methano - 6h - pyrazino [ 2 , 3 - h ][ 3 ] benzazepine ( compound v ) a 600 cc parr hastelloy reactor was charged under nitrogen with 10 g ( 28 . 9 mmol ) of compound vii , 3 % 1 wt . 300 mg of 5 % pd / c 50 % water wet and 200 ml ( 20 vols ) of a ipo / water ( 80 / 20 ) mixture . the reaction was placed under 45 - 50 psi of hydrogen at 28 - 30 ° c . for 4 hours . analysis by hplc confirmed the reaction to compound vi was complete . the reaction was filtered over celite , a 0 . 45 micron millipore filter and washed with 10 ml of ipo . the light yellow solution of compound vi was cooled to 0 - 5 ° c . and 4 . 49 g ( 30 . 9 mmol ) 1 . 07 eq . of fresh 40 % aqueous glyoxal ( aldrich ) diluted with 20 ml of water ( 8 % solution ) was added drop wise over a 1 hour period while maintaining 0 - 5 ° c . the light orange reaction ( ph = 6 . 9 ) was stirred for an additional 2 hours at 0 - 5 ° c . and 20 ° c . for 18 hrs . ( lighter in color ). analysis by hplc confirmed the reaction to compound v was complete . the reaction was vacuum concentrated to a volume of 85 ml ( 8 . 5 vols ) in a 40 - 45 ° c . water bath . the concentrate was cooled to 20 - 23 ° c . and 140 ml of water was added drop wise over 1 - 1 . 5 hours . the off - white suspension was granulated for 2 hours at 20 - 23 ° c ., filtered over a cotton cloth and washed with 10 ml of water . vacuum dried at 45 ° c . for 16 - 20 hours . this yielded 7 . 52 g ( 84 . 5 %) of an off - white to white solid compound of formula v having a purity of 99 . 9 % and a potency of 100 . 3 % as compared to a standard . the procedure in example 1 was repeated with the addition of ( 0 . 1 eq ) 0 . 07 ml of phosphoric acid dissolved in the aqueous glyoxal . the reaction mixture had an initial ph of 0 . 5 . upon completion of the cyclization , the reaction mixture was analyzed by hplc showing a 16 . 1 % formation of compound viii . the procedure in example 1 was repeated with the addition of ( 0 . 1 eg ) 3 . 1 ml of 1n sodium hydroxide dissolved in the aqueous glyoxal . the reaction mixture had a ph of 9 . 8 . upon completion of the cyclization , the reaction mixture was analyzed by hplc showing a non - detectable level of compound viii , but with two unknown impurities . the hydrolytic conversion of compound vii to the tartrate salt of compound i compound of formula v was slurried in a 2m naoh solution ( 3 . 1 equiv .). toluene ( 7 volumes ) was added and the biphasic slurry warmed to 37 - 40 ° c . the resulting yellow / brown biphasic mixture was maintained with stirring at 37 - 40 ° c . for 2 - 3 hours . once reaction was complete , an additional 10 volumes toluene was added , and the mixture stirred for 30 min . the biphasic system was taken off stir and the layers allowed to separate . the aqueous layer was collected , extracted with toluene ( 5 volumes ), and the toluene layers combined . the pot was vacuum distilled to 5 volumes . methanol ( 15 volumes ) was added , and the pot azeotropically distilled under vacuum to 5 volumes . methanol ( 10 volumes ) was added and again the pot azeotropically distilled under vacuum to 5 volumes . the resulting methanolic solution of compound i was diluted with additional methanol ( 18 volumes ), treated with darco kb - b ( 10 % w / w ) for 1 hour ( to remove color ), filtered , and transferred to an addition vessel . in a separate vessel , l -(+)- tartaric acid ( 1 . 1 equiv .) was dissolved in methanol ( 13 volumes ). the compound of formula i / meoh solution was then added dropwise to the l -(+)- tartaric acid / meoh solution . the resulting slurry was allowed to granulate for a minimum of 1 hour , filtered , rinsed with methanol , and allowed to dry under vacuum at 45 ° c . compound of formula v was slurried in a 1m naoh solution ( 3 . 1 equiv .). methylene chloride ( 2 . 5 volumes is added and the biphasic mixture stirred for 3 - 4 hours at room temperature . once reaction was complete an additional 7 . 5 volumes methylene chloride was added and the mixture stirred for 30 min . the biphasic system was taken off stir and the layers allowed to separate . the aqueous layer was collected , extracted with methylene chloride ( 5 volumes ), and the methylene chloride layers combined . the pot was atmospherically distilled to 5 volumes . methanol ( 10 volumes ) was added , and the pot distilled under partial vacuum to 5 volumes . methanol ( 5 volumes ) was added , and the pot distilled under full vacuum to 5 volumes . the resulting compound of formula i / meoh solution was diluted with additional methanol ( 18 volumes ), treated with darco kb - b ( 10 % w / w ) for 1 hour ( to remove color ), filtered , and transferred to an addition vessel . in a separate vessel , l -(+)- tartaric acid ( 1 . 1 equiv .) was dissolved in methanol ( 13 volumes ). the compound i / meoh solution was then added dropwise to the l -(+)- tartaric acid / meoh solution . the resulting slurry was allowed to granulate for a minimum of 1 hour , filtered , rinsed with methanol , and allowed to dry under vacuum at 45 ° c . starting from the same lot of compound of formula v , the tartrate salt of compound i was synthesized via both the toluene and methylene chloride processes . see the table below for results summary : as the table indicates , both the ch 2 cl 2 and toluene processes , where darco kb - b ™ was used , gave compound of formula i tartrate salt of comparable quality . this table further demonstrates how effective the darco kb - b ™ was at removing color from the toluene process ( uv - abs of 2 . 1 when darco kb - b ™ was used vs . 8 . 1 when darco kb - b ™ was not used , nearly a 4 × difference ). compound of formula i tartrate salt was dissolved in water ( 5 volumes ), followed by addition of toluene ( 10 volumes ). a 50 % naoh ( aq ) solution ( 2 . 2 equiv .) was added until the ph = 12 - 13 ( this was approximately 0 . 5 volumes of the naoh ( aq ) solution ). a particular lot was chosen as the starting material for the rework due to its color being more yellow than typical . after stirring for 1 . 5 hours at 37 - 40 ° c ., the layers were allowed to separate . the toluene layer was collected and set aside . the aqueous layer was extracted with toluene ( 5 volumes ), the toluene layers combined and vacuum distilled to 5 volumes . methanol ( 15 volumes ) was added and the pot azeotropically distilled under vacuum to 5 volumes . methanol ( 10 volumes ) was added , and again , the pot azeotropically distilled to 5 volumes . the resulting compound of formula i / meoh solution was diluted with methanol ( 18 volumes ). darco kb - b ™ ( 10 % w / w ) was added , stirred for one hour and filtered through a pad of celite . the methanolic solution of compound i was then transferred to an addition funnel . in a separate vessel , l -(+)- tartaric acid ( 1 . 1 equiv ) was dissolved in methanol ( 13 . 5 volumes ). the compound of formula i / meoh solution was then added dropwise to the l -(+)- tartaric acid / meoh solution . the resulting slurry was allowed to granulate for a minimum of 1 hour , filtered and dried . this gave an 80 % recovery of compound of formula i tartrate salt as a white solid . the formation of compound of formula viii is an indication of the side reactions which are occurring , and is not the only impurity peak observed in the assay of these materials . several of the additional impurities have not been identified ; however , the identification was not necessary as the impurities are controlled when the formation of compound of formula viii is controlled . thus , compound of formula viii is valuable as a marker showing that the process has been run in a manner to minimize the amount of impurities which may form . table 1 summarizes comparative data of two pilot plant production lots using conditions of the present invention with data obtained from two pilot plant runs using “ old process ” conditions of the prior art . thus , lower levels of compound of formula viii and other unidentified compounds , are present in compound of formula v when the process is properly controlled according to the teachings of the present invention . as shown in table 1 , the “ old ”, process resulted in 4800 to 1700 ppm of the compound of formula viii , while the present process resulted in dramatically reduced levels of 500 ppm or less . cyclization of 2 , 3 , 4 , 5 - tetrahydro - 3 -( trifluoroacetyl )- 1 , 5 - methano - 1h - 3 - benzazepine - 7 , 8 - diamine ( compound vi ) with glyoxal to form 7 , 8 , 9 , 10 - tetrahydro - 8 -( trifluoroacetyl )- 6 , 10 - methano - 6h - pyrazino [ 2 , 3 - h ][ 3 ] benzazepine ( compound v ) a 600 cc parr hastelloy b reactor was charged under nitrogen with 10 g ( 28 . 9 mmol ) of compound vii , 3 %/ wt . 300 mg of 5 % pd / c 50 % water wet and 200 ml ( 20 vols ) of a ipo / deionized water ( 80 / 20 ) mixture . the reaction was placed under 20 psi of hydrogen at 20 - 22 ° c . for 30 minutes , 20 psi for 30 min for 23 - 25 ° c . and 44 psi for 4 hours at 23 - 26 ° c . the reaction was filtered 26 - 28 ° c . over celite , a 0 . 45 micron millipore filter and washed with 40 ml of ipo ( total volume = 250 ml , ph = 9 . 6 ). to this light yellow solution of compound vi was added 0 . 51 g ( 0 . 1 eq ) of dibasic potassium phosphate , cooled to 3 - 6 ° c . and stirred at an rpm = 450 . when a temperature of 7 ° c . was obtained a thick suspension appeared . to this suspension at 3 - 6 ° c . ( ph = 9 . 6 ) was added a solution of 4 . 49 g ( 30 . 9 mmol ) 1 . 07 eq . of 40 % aqueous glyoxal diluted with 16 ml of deionized water ( 8 . 9 % solution , ph = 2 . 95 ) drop - wise over a 1 hour period ( total volume = 268 ml ). the light orange reaction was stirred for an additional 2 hours at 3 - 6 ° c . ( ph = 9 . 5 ) and then allowed to warm to 20 - 22 ° c . for 18 hrs . ( light yellow in color , ph = 9 . 3 ). analysis by hplc confirmed the reaction to compound v was complete and a level of 0 . 06 % compound viii was observed . the reaction was vacuum concentrated to a volume of 75 ml ( 7 . 5 vols ) in a 40 - 45 ° c . water - bath . the concentrate was cooled to 20 - 23 ° c . and 140 ml of deionized water was added dropwise over 1 hour ( k . f .= 82 %). the off - white suspension was granulated for 4 hours at 20 - 23 ° c ., filtered over a paper filter and washed with 20 ml of deionized water . vacuum dried at 45 ° c . for 16 - 20 hours . this yielded 7 . 85 g ( 88 . 2 %) of an off - white solid . cyclization of 2 , 3 , 4 , 5 - tetrahydro - 3 -( trifluoroacetyl )- 1 , 5 - methano - 1h - 3 - benzazepine - 7 , 8 - diamine ( compound vi ) with glyoxal to form 7 , 8 , 9 , 10 - tetrahydro - 8 -( trifluoroacetyl )- 6 , 10 - methano - 6h - pyrazino [ 2 , 3 - h ][ 3 ] benzazepine ( compound v ) the parr hastelloy b reactor from example 7 was charged with reagents following the example of example 7 above , but with the addition of 121 . 8 mg ( 0 . 05 eq ) of sodium bicarbonate to the filtered compound vi solution ( ph = 9 . 6 ). the procedure was repeated with 4 . 49 g ( 30 . 9 mmol ) 1 . 07 eq . of 40 % aqueous glyoxal diluted with 16 ml of deionized water ( 8 . 9 % solution , ph = 2 . 85 ) again added dropwise over a 60 minute period ( total volume = 268 ml ). the light orange reaction was stirred for an additional 2 hours at 3 - 6 ° c . ( ph = 9 . 4 ) and then allowed to warm to 20 - 22 ° c . for 18 hrs . ( light yellow in color , ph = 9 . 4 ). analysis by hplc confirmed the reaction to compound v was complete and a level of 0 . 06 % compound viii was observed . the reaction was vacuum concentrated to a volume of 75 ml ( 7 . 5 vols ) in a 40 - 45 ° c . water - bath . the concentrate was cooled to 20 - 23 ° c . and 140 ml of deionized water was added dropwise over 1 hour ( k . f .= 81 %, ph = 9 . 3 ). the off - white suspension was granulated for 4 hours at 20 - 23 ° c ., filtered over a paper filter and washed with 20 ml of deionized water . vacuum dried at 45 ° c . for 16 - 20 hours . this yielded 7 . 85 g ( 82 . 0 %) of an off - white solid .