in case of all the compounds described in wo2009037719 , r1 was never been ( ch 3 ) 2 nc ( o )—. during further work , we interestingly found that when r1 is ( ch 3 ) 2 nc ( o )— the compound has not only improved selectivity during in vitro assay but improved plasma dpp - iv inhibition in beagle dogs also . hence , the novel organic compounds of present invention represented by the general formula ( a ) is useful for reducing blood glucose , lowering lipid levels , cholesterol and reducing body weight and also have some excellent effects in the treatment and / or prophylaxis of diseases caused by insulin resistance such as type ii diabetes , hyperlipidemia , obesity , impaired glucose tolerance , diabetic complications with better efficacy , potency , without or reduced toxicity . the present invention is related to the compounds of the general formula a in exo configuration , the present invention relates more specifically to compound of formula ‘ 1 ’ and ‘ 2 ’; the compounds of the invention were prepared as outlined below according to the methods described herein . however , the invention is not limited to these methods , the compounds may also be prepared as described for structurally related compounds in the literature . intermediate i was prepared by the procedure provided in wo 2009 / 037719 a1 . compound of formula i was converted to compound of formula ii by a carbonyl insertion reaction between intermediate i and n , n dimethyl amine using triphosgene and diisopropyl ethyl amine ( u . s . pat . no . 5 , 362 , 744 ). other phosgene substitutes such as di - tert - butyl dicarbonate , 1 , 1 - carbonyl his imidazole can also be used . the compound of formula ii can also be prepared by treating compound of formula i with dimethyl carbamoyl chloride in halogenated hydrocarbon such as dichloromethane and in presence of base such as triethyl amine or diisopropyl ethyl amine at temperature such as 0 ° c .- room temperature for a suitable time . the ester group of formula ii can be hydrolyzed using any standard procedures known to a skilled artisan or by other procedures known in the literature such as in presence of a base such as k 2 co 3 , na 2 co 3 , lioh in a solvent such as methanol and h 2 o at temperature such as 0 ° c .- 30 ° c . for a suitable time 15 - 20 hours to obtain the compound of formula iii . compound of formula iii was converted to compound of formula v by condensation with compound of formula iv under standard peptide coupling conditions , for example , using edci , dicyclohexylcarbodiimide in presence of base such as triethyl amine , diisopropylethylamine and the like . the reaction may also be carried out in the presence of hobt . the reaction temperature may be in the range between 0 - 35 ° c ., the duration of reaction may range from 15 - 30 hours . if r is — conh 2 , then — conh 2 group is converted to — cn by treatment of dehydrating agent such as pocl 3 ; if r is — cooh , then such group is converted to — cn by converting it to — conh 2 and then treating the said amide with dehydrating agent such as pocl 3 . the compound of formula v was further deprotected using common methods known in the art such as using trifluoroacetic acid , in a solvent such as dichloromethane at a temperature 0 - 30 ° c . for 30 minutes to one hour to give the compounds of general formula a . the following examples are provided to further illustrate the present invention and therefore should not be construed to limit the scope of the invention . all 1 h nmr spectra were determined in the solvents indicated and chemical shifts are reported in δ units downfield from the internal standard tetramethylsilane ( tms ) and interproton coupling constants are reported in hertz ( hz ). to a stirred and cooled ( 0 ° c .) solution of triphosgene ( 2 . 0 g , 6 . 7 mmol ) in dichloromethane ( 100 ml ) was added a solution of methyl -( 2s )- 2 -( tert - butoxycarbonyl )- amino - 2 -[ 8 - aza - bicyclo [ 3 . 2 . 1 ]- oct - 3 - yl ]- exo - acetate ( 4 . 0 g , 13 . 4 mmol , prepared by following the procedure as described in wo 2009 / 037719 )) and diisopropylethylamine ( 5 . 05 ml , 3 . 78 g ., 29 . 3 mmol ) in dichloromethane ( 50 ml ) in a drop - wise manner in 30 minutes . after the addition was completed , the reaction mixture was brought to room temperature and stirred for 30 minutes . this mixture was again cooled to 0 ° c . and to this was added a solution of 2m solution of dimethyl amine in thf ( 16 . 6 ml , 1 . 51 g ., 33 . 5 mmol ) and diisopropyl ethyl amine ( 5 . 05 ml , 3 . 78 g ., 29 . 3 m mol ) in dichloromethane ( 50 ml ) in a drop - wise manner ( followed a procedure reported in u . s . pat . no . 5 , 362 , 744 ). the reaction mixture was stirred at room temperature and progress of reaction was monitored by tlc . after completion of reaction , the reaction mixture was concentrated under reduced pressure and diluted with ethyl acetate ( 250 ml ). the organic layer was washed with 5 % aqueous solution of khso 4 ( 30 ml ). the aqueous layer was neutralized to ph 7 . 0 and extracted with ethyl acetate ( 3 × 50 ml ). the combined organic layer was dried over anhydrous na 2 so 4 . the solvent was concentrated under reduced pressure to get a crude product , which was purified by column chromatography over silica gel ( 100 - 200 mesh ) using 2 % methanol in dichloromethane as an eluent to yield the title compound ( 3 . 8 g , 77 %). 1 h nmr ( cdcl 3 + d 2 o , 400 mhz ): δ 1 . 35 - 1 . 63 ( m , 15h ), 1 . 83 - 1 . 92 ( m , 2h ), 2 . 12 - 2 . 25 ( m , 1h ), 2 . 85 ( s , 6h ), 3 . 72 ( s , 3h ), 4 . 02 - 4 . 10 ( m , 2h ), 4 . 19 ( dd , j = 6 . 0 , 8 . 8 hz , 1h ), 5 . 04 ( d , j = 9 . 2 hz , 1h ), to a stirred and cooled ( 0 ° c .) solution of methyl -( 2s )- 2 -( tert - butoxycarbonyl )- amino - 2 -[ 8 -( dimethyl carbamoyl )- 8 - aza - bicyclo [ 3 . 2 . 1 ]- oct - 3 - yl ]- exo - acetate ( 4 . 2 g , 11 . 4 mmol ) in methanol ( 100 ml ) was added a solution of na 2 co 3 ( 6 . 03 g , 56 . 9 mmol ) in water ( 100 ml ) in a dropwise manner . after the addition was completed , the reaction mixture was stirred at room temperature for 24 hours . the progress of reaction was monitored by tlc . after completion of reaction , the reaction mixture was concentrated under reduced pressure to dryness . to this was added water ( 50 ml ), cooled to 0 ° c . and ph of the reaction mixture was adjusted to 6 . 5 with aqueous 10 % hcl . the solvent was then removed under reduced pressure to yield a solid , which was stirred with 15 % methanol in dichloromethane ( 3 × 200 ml ) at room temperature for 30 minutes . the reaction mixture was filtered through a buchner funnel and the filtrate was dried over anhydrous na 2 so 4 . the solvent was evaporated to yield the title compound ( 3 . 5 g ., 87 %), which was subjected to next step without purification . 1 h nmr ( d 2 o , 200 mhz ): δ 1 . 3 - 1 . 95 ( m , 17h ), 2 . 12 - 2 . 40 ( m , 1h ), 2 . 86 ( s , 6h ), 3 . 65 - 3 . 85 ( m , 1h ), 4 . 02 - 4 . 25 ( m , 2h ), to a stirred solution of ( 2s )- 2 -( tert - butoxycarbonyl )- amino - 2 -[ 8 -( dimethyl carbamoyl )- 8 - aza - bicyclo [ 3 . 2 . 1 ]- oct - 3 - yl ]- exo - ethanoic acid ( 1 . 0 g , 2 . 82 mmol ) in dmf ( 10 ml ) was added 1 - hydroxybenzotriazole monohydrate ( 1 . 3 g , 8 . 46 mmol ) and tfa salt of ( 1s , 3s , 5s ) 2 - azabicyclo [ 3 . 1 . 0 ]- hexane - 3 - carboxamide ( which can be prepared by using method as provided in wo 2004 / 052850 , 0 . 676 g , 2 . 82 mmol ) at room temperature . this reaction mixture was cooled to 0 ° c . and added triethyl amine ( 0 . 85 g , 1 . 2 ml , 8 . 46 mmol ) and 1 -( 3 - dimethyl amino propyl )- 3 - ethyl carbodiimide hydrochloride ( 1 . 08 g , 5 . 64 mmol ). the reaction mixture was then brought to room temperature in 15 minutes and stirred at room temperature for 18 hours . the solvent was removed under reduced pressure , diluted with ethyl acetate ( 60 ml ), washed with a saturated sodium bicarbonate solution ( 20 ml ), water ( 15 ml ) and brine ( 10 ml ). the organic layer was dried over anhydrous na 2 so 4 and the solvent was evaporated to get a crude product , which was purified by column chromatography over silica gel ( 100 - 200 mesh ) using methanol : nh 3 in chloroform : dichloromethane in the ratio of 3 : 10 : 87 as an eluent to yield the title compound ( 0 . 5 g , 59 %). 1 h nmr ( cdcl 3 + d 2 o , 400 mhz ): δ 0 . 80 - 0 . 87 ( m , 1h ), 0 . 95 - 1 . 02 ( m , 1h ), 1 . 42 ( s , 9h ), 1 . 48 - 1 . 65 ( m , 6h ), 1 . 70 - 1 . 78 ( m , 1h ), 1 . 85 - 1 . 92 ( m , 2h ), 2 . 24 - 2 . 40 ( m , 2h ), 2 . 45 ( dd , j = 2 . 4 , 13 . 2 hz , 1h ), 2 . 85 ( s , 6h ), 3 . 6 - 3 . 66 ( m , 1h ), 4 . 04 - 4 . 14 ( m , 2h ), 4 . 54 ( dd , j = 6 . 8 , 8 . 8 hz , 1h ), 4 . 82 ( dd , j = 2 . 4 , 10 . 8 hz , 1h ), 5 . 27 ( d , j = 9 . 6 hz , 1h ), to a stirred solution of ( 1s , 3s , 5s )- 2 -{( 2s )- 2 -( tert - butoxycarbonyl )- amino - 2 -[ 8 -( dimethyl carbamoyl )- 8 - aza - bicyclo [ 3 . 2 . 1 ]- oct - 3 - yl ]- exo - ethanoyl }- 2 - azabicyclo [ 3 . 1 . 0 ]- hexane - 3 - carboxamide ( 0 . 485 g , 1 . 05 mmol ) and imidazole ( 0 . 15 g , 2 . 2 mmol ) in dry pyridine ( 10 ml ) was added phosphorousoxychloride ( 0 . 658 g , 0 . 39 ml , 4 . 3 mmol ) drop wise at − 30 ° c . under n 2 atmosphere . the reaction mixture was stirred at − 30 ° c . for 90 minutes and quenched with water ( 1 ml ) at − 30 ° c . it was allowed to come to room temperature and the solvent was removed under reduced pressure at the same temperature . the crude product so obtained was dried under high vacuum and added dichloromethane ( 50 ml ), washed with water ( 10 ml ), dried over anhyd . na 2 so 4 . the solvent was evaporated to obtain a crude product , which was purified by column chromatography over silica gel ( 100 - 200 mesh ) using 2 % methanol in dichloromethane as an eluent to yield the title compound ( 0 . 35 g , 75 %). 1 h nmr ( cdcl 3 , 400 mhz ): δ 1 . 0 - 1 . 11 ( m , 2h ), 1 . 42 ( s , 9h ), 1 . 50 - 1 . 70 ( m , 6h ), 1 . 84 - 1 . 97 ( m , 3h ), 2 . 26 - 2 . 42 ( m , 2h ), 2 . 54 - 2 . 63 ( m , 1h ), 2 . 87 ( s , 6h ), 3 . 77 - 3 . 85 ( m , 1h ), 4 . 05 - 4 . 16 ( m , 2h ), 4 . 48 ( t , j = 8 . 4 hz , 1h ), 5 . 0 ( dd , j = 2 . 0 , 10 . 4 hz , 1h ), 5 . 17 ( d , j = 9 . 2 hz , 1h ) to a stirred cooled ( 0 ° c .) solution of ( 1s , 3s , 5s )- 2 -{( 2s )- 2 -( tert - butoxycarbonyl ) amino - 2 -[ 8 -( dimethyl carbamoyl )- 8 - aza - bicyclo [ 3 . 2 . 1 ]- oct - 3 - yl ]- exo - ethanoyl }- 2 - azabicyclo [ 3 . 1 . 0 ]- hexane - 3 - carbonitrile ( 0 . 335 g , 0 . 75 mmol ) in dichloromethane ( 3 . 5 ml ) was added a solution of trifluoro acetic acid ( 3 . 5 ml , 5 . 36 g , 47 mmol ) in dichloromethane ( 3 . 5 ml ) drop wise at 0 ° c . the reaction mixture was stirred at 0 ° c . for 5 minutes , brought to room temperature and stirred at room temperature for 45 min . the solvent was evaporated under reduced pressure at 30 ° c . and added dichloromethane ( 20 ml ). the solvent was again evaporated and dried under high vacuum . in order to solidify the product , petroleum ether ( 20 ml ) was added and evaporated . this process was repeated twice . to remove traces of trifluoroacetic acid , the reaction mixture was stirred at room temperature with diethyl ether ( 2 × 15 ml ) and filtered to yield the title compound ( 0 . 295 g , 85 %). 1 h nmr ( d 2 o , 400 mhz ): δ 0 . 91 - 0 . 97 ( m , 1h ), 1 . 14 - 1 . 22 ( m , 1h ), 1 . 53 - 1 . 80 ( m , 6h ), 1 . 83 - 1 . 95 ( m , 2h ), 2 . 0 - 2 . 07 ( m , 1h ), 2 . 41 ( dd , j = 2 . 0 , 13 . 6 hz , 1h ), 2 . 63 - 2 . 77 ( m , 2h ), 2 . 86 ( s , 6h ), 3 . 73 - 3 . 79 ( m , 1h ), 4 . 14 - 4 . 22 ( m , 2h ), 4 . 48 ( d , j = 6 hz , 1h ), 5 . 16 ( dd , j = 2 . 0 , 10 . 8 hz , 1h ), to a stirred solution of ( 2s )- 2 -( tert - butoxycarbonyl )- amino - 2 -[ 8 -( dimethyl carbamoyl )- 8 - aza - bicyclo [ 3 . 2 . 1 ]- oct - 3 - yl ]- exo - ethanoic acid ( step - 1 of example 1 , 1 . 2 g , 3 . 38 mmol ) in dry dmf ( 15 ml ) was added 1 - hydroxybenzotriazole monohydrate ( 1 . 55 g , 10 . 14 mmol ) and 5 - ethynyl - pyrrolidin - 2 - carboxamide trifluoro acetic acid salt ( which can be prepared by the procedure provided in wo 2008 / 011499 and wo 2009 / 037719 a1 , 0 . 85 g , 3 . 38 mmol ) at room temperature . the reaction mixture was cooled to 0 ° c . and added 1 -( 3 - dimethyl amino propyl )- 3 - ethyl carbodimide hydrochloride ( 1 . 3 g , 6 . 76 mmol ) followed by triethyl amine ( 1 . 41 ml , 1 . 02 g , 10 . 14 mmol ). the reaction mixture was stirred at 0 ° c . for 5 minutes and then at room temperature for 18 hours . the solvent was evaporated under reduced pressure at 35 ° c . to this residue , was added water ( 15 ml ) and extracted with ethyl acetate ( 3 × 50 ml ). the combined organic layer was washed with a saturated sodium bicarbonate solution ( 15 ml ) and dried over anhydrous na 2 so 4 . the solvent was evaporated under reduced pressure to get a crude product , which was purified by column chromatography over silica gel ( 100 - 200 mesh ) using 2 % methanol in dichloromethane as an eluent to yield the title compound ( 0 . 46 g , 29 %). 1 h nmr ( cdcl 3 , 400 mhz ): δ 1 . 32 - 1 . 66 ( m , 14h ), 1 . 70 - 1 . 80 ( m , 1h ), 1 . 82 - 1 . 94 ( m , 2h ), 2 . 10 - 2 . 25 ( m , 3h ), 2 . 28 - 2 . 52 ( m , 2h ), ( d , j = 2 . 0 hz , 1h ), 2 . 85 ( s , 6h ), 4 . 03 - 4 . 12 ( m , 2h ), 4 . 42 ( dd , j = 7 . 6 , 9 . 2 hz , 1h ), 4 . 54 ( t , j = 7 . 6 , hz , 1h ), 5 . 05 - 5 . 14 ( m , 2h ), 5 . 47 - 5 . 54 ( m , 1h ), 6 . 35 - 6 . 45 ( m , 1h ). to a stirred solution of ( 2s , 5r )- 1 -{( 2s )- 2 -( tert - butoxycarbonyl )- amino - 2 -[ 8 -( dimethyl carbamoyl )- 8 - aza - bicyclo [ 3 . 2 . 1 ] oct - 3 - yl ]- exo - ethanoyl }- 5 - ethynyl - pyrrolidin - 2 - carboxamide ( 0 . 41 g , 0 . 863 mmol ) and imidazole ( 0 . 117 g , 1 . 72 mmol ) in dry pyridine ( 7 . 0 ml ) was added phosphorousoxychloride ( 0 . 32 ml , 0 . 53 g , 3 . 45 mmol ) dropwise at − 35 ° c . under nitrogen atmosphere . the reaction mixture was then stirred at − 20 ° c . to − 10 ° c . for 3 . 0 hours . the completion of reaction was monitored by tlc . after completion , the reaction mixture was quenched with water ( 2 ml ) at − 30 ° c . and then it was allowed to come to room temperature . the solvent was removed under reduced pressure . the crude product was taken in water ( 20 ml ) and extracted with dichloromethane ( 3 × 50 ml ). the combined organic layers were dried over anhydrous na 2 so 4 , filtered and concentrated at reduced pressure to yield a crude product ; which was purified by column chromatography over silica gel ( 100 - 200 mesh ) using 2 % methanol in dichloromethane as an eluant to obtain the title compound ( 0 . 31 g , 79 %). mp : 88 - 90 ° c . 1 h nmr ( cdcl 3 + d 2 o , 400 mhz ): δ 1 . 40 ( s , 9h ), 1 . 49 - 1 . 70 ( m , 5h ), 1 . 71 - 1 . 80 ( m , 1h ), 1 . 82 - 1 . 94 ( m , 2h ), 2 . 15 - 2 . 56 ( m , 6h ), 2 . 86 ( s , 6h ), 4 . 03 - 4 . 14 ( m , 2h ), 4 . 29 ( t , j = 8 . 0 hz , 1h ), 4 . 67 ( t , j = 8 . 4 hz , 1h ), 5 . 04 ( d , j = 8 . 8 hz , 1h ), 5 . 15 - 5 . 21 ( m , 1h ). to a stirred solution of ( 2s , 5r )- 1 -{( 2s )- 2 -( tert - butoxycarbonyl )- amino - 2 -[ 8 -( dimethyl carbamoyl )- 8 - aza - bicyclo [ 3 . 2 . 1 ]- oct - 3 - yl ]- exo - ethanoyl }- 5 - ethynyl - pyrrolidin - 2 - carbonitrile ( 0 . 30 g , 0 . 656 mmol ) in dry dichloromethane ( 3 ml ) was added a solution trifluoroacetic acid ( 3 . 0 ml , 4 . 44 g , 38 . 94 mmol ) in dry dichloromethane ( 3 ml ) at 0 ° c . after the addition was completed , reaction mixture was stirred at room temperature for 30 minutes . the solvent was evaporated under reduced pressure at 30 ° c . and added dichloromethane ( 20 ml ). the solvent was again evaporated and dried under high vacuum . in order to solidify the product , petroleum ether ( 10 ml ) was added and evaporated . the solid product was then washed with diethyl ether ( 2 × 10 ml ) and dried under high vacuum for four hours to yield the title compound ( 0 . 265 g , 86 %). 1 h nmr ( d 2 o , 400 mhz ): δ 1 . 48 - 1 . 56 ( m , 1h ), 1 . 6 - 1 . 74 ( m , 4h ), 1 . 77 - 1 . 93 ( m , 3h ), 2 . 13 - 2 . 23 ( m , 1h ), 2 . 25 - 2 . 33 ( m , 1h ), 2 . 52 - 2 . 62 ( m , 2h ), 2 . 75 - 2 . 88 ( m , 7h ), 3 . 13 ( d , j = 2 . 4 hz , 1h ), 4 . 13 - 4 . 22 ( m , 2h ), 4 . 38 ( d , j = 6 . 0 hz , 1h ), 4 . 77 - 4 . 85 ( m , 1h ), 5 . 01 ( d , j = 7 . 2 hz , 1h ), the proteolytic activity of human recombinant dpp - iv was determined by following the hydrolysis of gly - pro - 7 - amino - 4 - methylcoumarin ( gly - pro - amc ) and the fluorometric quantitation of the liberated amc . assays were routinely carried out in 96 - well flat - bottom black microwell plates . the reaction mixture ( 100 μl ) contained 10 ng of human recombinant dpp - iv enzyme ( produced in - house or procured from r & amp ; d systems , usa ) in the assay buffer ( 25 mm tris - hcl , ph 7 . 4 , 140 mm nacl , 10 mm kcl and 0 . 1 mg / ml bsa ) and 50 μm gly - pro - amc . after incubation of assay plates at 30 ° c . for 30 min , the hydrolysis of gly - pro - amc was monitored in a fluorescence microplate reader ( molecular devices spectramax m5 ), with excitation and emission wavelengths set at 360 nm and 460 nm , respectively . the inhibition of dpp - iv activity by test compounds was routinely performed by preincubating the enzyme with test compound ( 10 and 100 nm for primary screening and 8 concentrations from 0 . 1 to 1000 nm for the dose - response study ) or vehicle ( 0 . 01 % dmso ) for 15 min at 30 ° c ., in a total volume of 90 μl . test compounds were dissolved in dmso at a concentration of 10 mm and serially diluted further in assay buffer . the enzyme reaction was initiated by the addition of gly - pro - amc , followed by incubation of assay plates for 30 min at 30 ° c . and the liberated amc was measured as described above . a known inhibitor of dpp - iv ( positive control ) was always included in the assay . test compounds at various concentrations were always evaluated in duplicate , along with substrate blanks , vehicle controls and positive controls . the results are expressed as percent inhibition of the enzyme activity relative to vehicle controls . dose - response studies were conducted for those compounds exerting ≧ 50 % inhibition of activity at 10 nm in primary screening . ic 50 , defined as the inhibitor concentration which caused a 50 % decrease of the activity under assay conditions , was computed using graphpad prism software , version 5 . 0 . the dpp - iv inhibition data ( expressed either as ic 50 in nanomolar or percent inhibition at a particular compound concentration ) is presented in table 1 . overnight - fasted male animals were administered either vehicle or single oral dose of compound . blood samples were collected prior to dosing and for 12 hours post dose into tubes containing edta . edta - plasma was separated and dpp - iv activity was measured using a fluorometric assay . assays were carried out in 96 - well flat - bottom black microwell plates . a typical reaction contained 25 μl plasma , 50 μl of 50 μm substrate ( gly - pro - amc ) and 25 μl assay buffer ( 25 mm tris - hcl , ph 7 . 4 , 140 mm nacl , 10 mm kcl and 1 % bsa ) in a total reaction volume of 100 μl . plasma samples were incubated with the substrate for 30 min at 30 ° c ., following which the fluorescence was measured in a microplate fluorescence reader ( polarstar galaxy ), with excitation and emission wavelengths set at 360 nm and 460 nm , respectively . percent inhibition in plasma dpp - iv activity due to compounds was calculated by comparing with plasma from vehicle - treated animals . table ii shows the ability of compound 2 to produce inhibition of plasma dpp - iv in male beagle dogs
the present invention is related to novel 2 - amino - 2 -- 8 - aza - bicyclooct - 3 - yl ]- exo - ethanoyl derivatives of the general formula , their tautomeric forms , their stereoisomers , their pharmaceutically acceptable salts , pharmaceutical compositions containing them , methods of making of the above compounds , and their use as dipeptidyl peptidase - iv inhibitors , which are useful in the treatment or prevention of diseases particularly type ii diabetes , other complications related to diabetes and other pathogenic conditions in which dpp iv enzyme is involved .