it is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention claimed . as used herein , the use of the singular includes the plural unless specifically stated otherwise . it will be readily apparent to those skilled in the art that some of the compounds of the invention may contain one or more asymmetric centers , such that the compounds may exist in enantiomeric as well as in diastereomeric forms . unless it is specifically noted otherwise , the scope of the present invention includes all enantiomers , diastereomers and racemic mixtures . some of the compounds of the invention may form salts with pharmaceutically acceptable acids or bases , and such pharmaceutically acceptable salts of the compounds described herein are also within the scope of the invention . the present invention includes all pharmaceutically acceptable isotopically enriched compounds . any compound of the invention may contain one or more isotopic atoms enriched or different than the natural ratio such as deuterium 2 h ( or d ) in place of hydrogen 1 h ( or h ) or use of 13 c enriched material in place of 12 c and the like . similar substitutions can be employed for n , o and s . the use of isotopes may assist in analytical as well as therapeutic aspects of the invention . for example , use of deuterium may increase the in vivo half - life by altering the metabolism ( rate ) of the compounds of the invention . these compounds can be prepared in accord with the preparations described by use of isotopically enriched reagents . the following examples are for illustrative purposes only and are not intended , nor should they be construed as limiting the invention in any manner . those skilled in the art will appreciate that variations and modifications of the following examples can be made without exceeding the spirit or scope of the invention . as will be evident to those skilled in the art , individual isomeric forms can be obtained by separation of mixtures thereof in conventional manner . for example , in the case of diasteroisomeric isomers , chromatographic separation may be employed . compound names were generated with acd version 12 . 5 ; some intermediates &# 39 ; and reagents &# 39 ; names used in the examples were generated with softwares such as chem bio draw ultra version 12 . 0 , acd version 12 . 5 or auto nom 2000 from mdl isis draw 2 . 5 sp1 . in general , characterization of the compounds was performed using nmr spectra , which were recorded on 300 or 600 mhz varian and acquired at room temperature . chemical shifts are given in ppm referenced either to internal tms or to the solvent signal . the optical rotation was recorded on perkin elmer polarimeter 341 , 589 nm at 20 ° c ., na / hal lamp . all the reagents , solvents , catalysts for which the synthesis is not described are purchased from chemical vendors such as sigma aldrich , fluka , bio - blocks , combi - blocks , tci , vwr , lancaster , oakwood , trans world chemical , alfa , fisher , maybridge , frontier , matrix , ukrorgsynth , toronto , ryan scientific , silicycle , anaspec , syn chem , chem - impex , mic - scientific , ltd ; however some known intermediates , were prepared according to published procedures . usually the compounds of the invention were purified by column chromatography ( auto - column ) on teledyne - isco combiflash with a silica column , unless noted otherwise . enantiomers of racemic compounds were separated by chiral stationary phase high pressure liquid chromatography . the following synthetic procedures illustrate how compounds according to the invention can be made . those skilled in the art will be routinely able to modify and / or adapt the following schemes to synthesize any compound of the invention covered by formula i . to a solution of , di - 1h - imidazol - 1 - yl - methanone cas 530 - 62 - 1 ( 486 mg , 3 mmol ) in dioxane ( 10 ml ) was added a solution of 1 , 1 - dimethylethyl ester hydrazinecarboxylic acid , cas 870 - 46 - 2 ( 330 mg , 2 . 5 mmol ) in dioxane ( 10 ml ) and stirred for 90 min at ambient temperature . then , 2 - amino - 2 , 3 - dihydro - 1h - indene - 2 - carboxylic acid methyl ester , cas 199330 - 64 - 8 ( 570 mg , 2 . 5 mmol ) was added as solid to the reaction , immediately followed by et 3 n ( 505 mg , 5 mmol ). the reaction was then heated to 65 ° c . for 4 h . the reaction mixture was concentrated to ˜ 15 ml , and allowed to settle at ambient temperature . intermediate 1 separated as a white solid and was collected by filtration . 1 hnmr ( cdcl 3 ): δ 1 . 50 ( s , 9h ), 3 . 16 ( br d , j = 15 hz , 2h ), 3 . 69 ( d , j = 15 hz , 2h ), 7 . 23 ( br s , 4h ). to a cold (− 78 ° c .) intermediate 1 ( 300 mg , 0 . 94 mmol ) was added cf 3 co 2 h ( 3 ml ). then the cooling bath was removed and the stirred reaction mixture was allowed to warm at ambient temperature . after 30 min . all the cf 3 co 2 h was removed and the crude mixture was quenched by aq . nahco 3 until alkaline . the mixture was extracted with ch 2 cl 2 ( 2 × 30 ml ). the organic layers were combined and dried with mgso 4 , and filtered and the solvent was removed under reduced pressure . intermediate 2 was isolated . 1 hnmr ( cd 3 od ): δ 3 . 10 ( d , j = 16 . 2 hz , 2h ), 3 . 51 ( d , j = 16 . 2 hz , 2h ), 7 . 19 - 7 . 25 ( m , 4h ). to a cold solution ( 0 ° c .) of 1 - hydroxy - 4 - methylpentan - 3 - one cas 132350 - 33 - 5 ( 580 mg , 5 mmol ) in ch 2 cl 2 ( 8 ml ) was added camphor sulfonic acid ( 58 mg ) followed by a solution of 4 - methoxybenzyl - 2 , 2 , 2 - trichloroacetimidate cas 89238 - 99 - 3 ( 1 . 42 g , 5 mmol ) in ch 2 cl 2 ( 8 ml ) was added and stirred at rt for 16 h . the reaction was quenched by adding aq . nahco 3 ( 10 ml ), extracted with ch 2 cl 2 ( 30 ml ). the organic layer was dried ( mgso 4 ) and solvent removed under reduced pressure . the crude product was purified by silicagel chromatography using etoac in hexane as eluent . intermediate 3 was isolated as a colorless oil . 1 hnmr ( cdcl 3 ): δ 1 . 10 ( d , j = 6 . 9 hz , 6h ), 2 . 50 - 2 . 67 ( m , 1h ), 2 . 74 ( t , j = 6 . 6 hz , 2h ), 3 . 71 ( t , j = 6 . 6 hz , 2h ), 3 . 80 ( s , 3h ), 4 . 44 ( s , 2h ), 6 . 84 - 6 . 89 ( m , 2h ), 7 . 21 - 7 . 27 ( m , 2h to a cold (− 78 ° c .) solution of n - methoxy - 2 -(( 4 - methoxybenzyl ) oxy )- n - methylacetamide cas 191731 - 32 - 5 ( 856 mg , 3 . 6 mmol ) in thf ( 10 ml ) was added i - prmgcl - thf solution . then the reaction was warmed to rt , and stirred for 2 h , the reaction mixture was poured into cold 2n hcl and extracted with etoac , the organic layer was dried ( mgso 4 ) and solvent removed under reduced pressure . the crude mixture was purified by silicagel chromatography using etoac in hexane . intermediate 4 was isolated as a colorless oil . 1 hnmr ( cdcl 3 ): δ 1 . 08 ( d , j = 6 . 7 hz , 6h ), 2 . 70 - 2 . 91 ( m , 1h ), 3 . 80 ( s , 3h ), 4 . 10 ( s , 2h ), 4 . 52 ( s , 2h ), 6 . 88 ( d , j = 8 . 8 hz , 2h ), 7 . 28 ( d , j = 8 . 8 hz , 2h ). a mixture of intermediate 3 1 . 82 g , 10 mmol ), ( nh 4 ) 2 co 3 ( 4 . 24 g , 40 mmol ), kcn ( 2 . 5 g , 37 . 5 mmol ) and etoh ( 20 ml ) was heated to 60 ° c . for 15 h . the crude mixture was filtered through a short celite column . then the solvent was removed under reduced pressure and intermediate 5 was isolated as a solid . 1 hnmr ( cdcl 3 ): δ 0 . 94 ( d , j = 4 . 2 hz , 3h ), 0 . 96 ( d , j = 4 . 2 hz , 3h ), 1 . 90 - 2 . 21 ( m , 3h ), 3 . 41 - 3 . 60 ( m , 2h ), 3 . 78 ( s , 3h ), 4 . 34 ( d , j = 8 . 4 hz , 1h ), 4 . 38 ( d , j = 8 . 4 hz , 1h ), 6 . 80 - 6 . 90 ( m , 2h ), 7 . 20 - 7 . 27 ( m , 2h ). intermediates 6 through 10 were prepared in a similar manner to the procedure described in example 5 for intermediate 5 . the starting materials used and the results are tabulated below in table 1 . a mixture of 5 - ethyl - 5 -( 1 - methylethyl )- 2 , 4 - imidazolidinedione cas 98492 - 91 - 2 ( 2 . 47 g , 14 . 53 mmol ) and hydrazine hydrate ( 10 ml ) was heated at 150 ° c . in a sealed tube for 5 days . the crude mixture was purified by silica gel flash chromatography using meoh : ch 2 cl 2 , ( 1 : 19 ). intermediate 12 was isolated as a white solid . 1 hnmr ( cd 3 od ): δ 0 . 78 - 0 . 92 ( m , 6h ), 0 . 95 ( d , j = 6 . 00 hz , 3h ), 1 . 78 ( q , j = 7 . 33 hz , 2h ), 1 . 96 - 2 . 06 ( m , 1h ). intermediates 13 through 19 were prepared in a similar manner to the procedure described in example 6 for intermediate 12 . the starting material used and the results are tabulated below in table 2 . a mixture of 4 -( 4 - chlorophenyl ) butan - 2 - one cas 3506 - 75 - 0 ( 1 . 82 g , 10 mmol ), ( nh 4 ) 2 co 3 ( 4 . 24 g , 40 mmol ), kcn ( 2 . 5 g , 37 . 5 mmol ) and etoh ( 20 ml ) was heated to 60 ° c . for 15 h . the crude mixture was filtered through a short celite column . then the solvent was removed under reduced pressure . intermediate 5 -( 4 - chlorophenethyl )- 5 - methylimidazolidine - 2 , 4 - dione was isolated as a brown solid . a mixture of 5 -( 4 - chlorophenethyl )- 5 - methylimidazolidine - 2 , 4 - dione ( 400 mg , 1 . 9 mmol ) and hydrazine hydrate ( 4 ml ) was heated to 100 ° c . for 5 h in a sealed tube . this mixture was purified by silicagel chromatography using meoh in ch 2 cl 2 as eluent , and intermediate 20 was isolated as a white solid . 1 hnmr ( cd 3 od ): δ 1 . 40 ( s , 3h ), 1 . 82 - 1 . 95 ( m , 1h ), 2 . 01 - 2 . 10 ( m , 1h ), 2 . 40 - 2 . 46 ( m , 1h ), 2 . 58 - 2 . 66 ( m , 1h ), 7 . 14 ( d , j = 8 . 4 hz , 2h ), 7 . 25 ( d , j = 8 . 4 hz , 2h ). intermediates 21 through 31 were prepared in a similar manner to the procedure described in example 7 for intermediate 20 . the starting materials used and the results are tabulated below in table 3 . a mixture of intermediate 5 ( 320 mg , 1 . 05 mmol ), k 2 co 3 , dmf ( 3 ml ), thf ( 3 ml ) was heated to 70 ° c . and o -( 2 , 4 - dinitrophenyl ) hydroxylamine cas 17508 - 17 - 7 ( 224 mg , 1 . 55 mmol ) was added in one portion . at 15 minute intervals o -( 2 , 4 - dinitrophenyl ) hydroxylamine cas 17508 - 17 - 7 ( 112 mg each time ) and k 2 co 3 ( 120 mg ) were added four times . the mixture was cooled to rt , extracted with etoac ( 70 ml ), washed with aq . k 2 co 3 , dried ( mgso 4 ) and solvent removed . the crude intermediate was purified by silicagel chromatography using etoac in hexane as eluent and intermediate 32 was isolated . 1 hnmr ( cd 3 od ): δ 0 . 86 ( d , j = 4 . 2 hz , 3h ), 0 . 95 ( d , j = 4 . 2 hz , 3h ), 1 . 94 - 2 . 00 ( m , 2h ), 2 . 18 - 2 . 22 ( m , 1h ), 3 . 45 - 3 . 50 ( m , 2h ), 3 . 77 ( s , 3h ), 4 . 26 ( d , j = 10 . 8 hz , 1h ), 4 . 34 ( d , j = 10 . 8 hz , 1h ), 6 . 82 - 6 . 90 ( m , 2h ), 7 . 20 - 7 . 24 ( m , 2h ). intermediates 33 through 39 were prepared in a similar manner to the procedure described in example 8 for intermediate 32 . the starting materials used and the results are tabulated below in table 4 . intermediate 33 ( 460 mg , 1 . 5 mmol ), phosphine , 1 , 1 ′-( 1 , 3 - propanediyl ) bis [ 1 , 1 - d ] cyclohexyl -, tetrafluoroborate ( 1 -) cas 1002345 - 50 - 7 ( 40 mg , 0 . 08 mmol ), pd ( oac ) 2 ( 9 mg ), k 2 co 3 ( 600 mg , 4 . 5 mmol ), molecular sieves ( 4a , 600 mg ) dmso ( 6 ml ) were bubbled with carbon monoxide then meoh ( 250 mg ) was added to the reaction and the reaction was covered with a rubber septum and a carbon monoxide filled balloon was inserted into the septum . the reaction was heated to 75 ° c . for 16 h and was worked up by removing the solvent under reduced pressure , the crude was purified by silicagel chromatography using 5 % 7n nh 3 - meoh and 95 % ch 2 cl 2 . intermediate 41 was isolated as a white solid . 1 hnmr ( cd 3 od ): δ 1 . 41 ( s , 3h ), 1 . 90 - 1 . 97 ( m , 1h ), 2 . 07 - 2 . 14 ( m , 1h ), 2 . 52 - 2 . 54 ( m , 1h ), 2 . 66 - 2 . 71 ( m , 1h ), 3 . 88 ( s , 3h ), 7 . 27 ( d , j = 8 . 4 hz , 2h ), 7 . 91 ( dd , j = 8 . 4 , 1 . 8 hz , 2h ). intermediates 42 and 43 were prepared in a similar manner to the procedure described in example 9 for intermediate 41 . the starting materials used and the results are tabulated below in table 5 . a mixture of 3 - amino - 5 , 5 - diethylimidazolidine - 2 , 4 - dione cas 1007 - 61 - 0 ( 70 mg , 0 . 4 mmol ), 4 - bromophenylisocyanate cas 2493 - 02 - 9 ( 80 mg , 0 . 4 mmol ) in toluene ( 5 ml ) was heated at 100 ° c . for 8 h . upon cooling the reaction to ambient temperature , compound 1 separated as a white solid , which was collected by filtration and dried under high vacuum . 1 hnmr ( cd 3 od ): δ 0 . 95 ( br s , 6h ), 1 . 65 - 1 . 75 ( m , 2h ), 1 . 81 - 1 . 91 ( m , 2h ), 7 . 36 ( d , j = 6 . 00 hz , 2h ), 7 . 40 ( d , j = 6 . 00 hz , 2h ). compounds 2 through 68 were prepared in a similar manner to the procedure described in example 10 for compound 1 . the starting materials used and the results are tabulated below in table 6 . racemic compound 9 was separated into the individual enantiomers compound 70 and compound 71 , by chiral stationary phase high pressure liquid chromatography : preparative column ( ic , 2 × 15 cm ) and mobile phase ( super critical fluid ) 20 % methanol ( 0 . 1 % dea )/ co 2 , 100 bar ; 70 ml / min , uv 220 nm . racemic compound 18 was separated into the individual enantiomers , compound 72 and compound 73 , by chiral stationary phase high pressure liquid chromatography : preparative column ( ia , 2 × 15 cm ) and mobile phase ( super critical fluid ) 50 % methanol ( 0 . 1 % dea )/ co 2 , 100 bar ; 70 ml / min , uv 254 nm . to a cold ( 0 ° c .) solution of compound 56 ( 100 mg , 0 . 2 mmol ) in ch 2 cl 2 ( 5 ml ) was added ddq , cas 84 - 58 - 2 ( 100 mg , 0 . 4 mmol ) and stirred for 90 min . to the reaction saturated sodium thiosulfate ( 2 ml ) was added and stirred for 30 min . the solvent removed under reduced pressure and purified by silicagel chromatography using meoh in ch 2 cl 2 . the product was obtained as a white solid . 1 hnmr ( cd 3 od ): δ 0 . 98 ( d , j = 7 . 0 hz , 6h ), 2 . 06 - 2 . 20 ( m , 1h ), 3 . 75 - 3 . 90 ( m , 2h ), 7 . 31 - 7 . 41 ( m , 4h ). compounds 75 and 76 were prepared in a similar manner to the procedure described in example 13 for compound 74 . the starting materials used and the results are tabulated below in table 7 . to a solution of compound 58 ( 30 mg , 0 . 06 mmol ) in dioxane ( 2 ml ) was added koh — h 2 o ( 0 . 5m solution , 1 ml ) was added and stirred at rt for 90 min . solvent was removed under reduced pressure , then the reaction was cooled ( 0 ° c .) and acidified to ph 2 with 10 % hcl . the crude product was purified by silicagel chromatography using meoh in ch 2 cl 2 . compound 77 was isolated as a white solid . 1 hnmr ( cd 3 od ): δ 1 . 50 ( s , 3h ), 1 . 92 - 2 . 03 ( m , 1h ), 2 . 11 - 2 . 21 ( m , 1h ), 2 . 62 - 2 . 85 ( m , 2h ), 7 . 32 ( d , j = 7 . 8 hz , 2h ), 7 . 35 - 7 . 45 ( m , 4h ), 7 . 92 - 7 . 97 ( m , 2h ). compounds 78 through 83 were prepared in a similar manner to the procedure described in example 14 for compound 77 . the starting materials used and the results are tabulated below in table 8 . to a solution of compound 81 ( 50 mg , 0 . 12 mmol ) in ch 2 cl 2 ( 5 ml ) was added ethanolamine ( 15 mg , 0 . 24 mmol ), propyl propionic anhydride ( 0 . 1 ml , 50 % wt / wt in etoac ), et 3 n ( 61 mg , 0 . 6 mmol ), dmap ( 4 mg ) and stirred at rt for 18 h . the solvent was removed on rotavapor and the crude reaction was purified by preparative thin layer chromatography . compound 84 was isolated as white solid . 1 h nmr ( cd 3 od ) δ 0 . 90 - 1 . 08 ( m , 6h ), 1 . 97 - 2 . 09 ( m , 1h ), 2 . 92 ( d , j = 9 . 4 hz , 2h ), 3 . 52 - 3 . 66 ( m , 4h ), 7 . 31 - 7 . 47 ( m , 2h ), 7 . 56 ( br . s , 2h ). compounds 85 through 91 were prepared in a similar manner to the procedure described in example 15 for compound 84 . the starting materials used and the results are tabulated below in table 9 . to compound 85 ( 131 mg , 0 . 23 mmol ) was added formic acid ( 3 ml ) and stirred at rt for 1 h . the solvent was removed at rt under vacuum . compound 92 was isolated as white solid . 1 h nmr ( cd 3 od ) δ 0 . 94 ( d , j = 6 . 5 hz , 3h ), 1 . 03 ( d , j = 6 . 9 hz , 3h ), 2 . 03 ( m , 1h ), 3 . 00 ( d , j = 6 . 2 hz , 2h ), 3 . 90 ( d , j = 4 . 4 hz , 2h ), 7 . 37 ( d , j = 8 . 9 hz , 2h ), 7 . 47 - 7 . 60 ( m , 2h ). compounds 93 through 96 were prepared in a similar manner to the procedure described in example 16 for compound 92 . the starting materials used and the results are tabulated below in table 10 . to a cold (− 31 ° c .) turbid mixture of compound 92 ( 180 mg , 0 . 38 mmol ) in thf ( 5 ml ) was added et 3 n ( 118 mg , 1 . 18 mmol ). after 5 min cico 2 et ( 66 mg , 0 . 61 mmol ) was added and stirred for 20 min . nh 3 gas was bubbled through the reaction mixture . then the reaction was gradually warmed to rt . the crude reaction was purified by silicagel chromatography eluting with 10 % meoh in ch 2 cl 2 . the product was then washed with 10 % hcl to remove basic impurities in the product . the compound 96 was isolated as a white solid . 1 h nmr ( methanol - d 4 ) δ 0 . 95 ( d , j = 6 . 6 hz , 3h ), 1 . 03 ( d , j = 6 . 9 hz , 3h ), 1 . 94 - 2 . 12 ( m , 1h ), 2 . 88 - 3 . 14 ( m , 2h ), 3 . 84 ( d , j = 11 . 0 hz , 2h ), 7 . 33 - 7 . 47 ( m , 2h ), 7 . 49 - 7 . 63 ( m , 2h ). biological activity of compounds according to formula i is set forth in table 11 below . hek - gα16 and cho - gα16 cells stably expressing fprl1 were cultured in ( f12 , 10 % fbs , 1 % psa , 400 μg / ml geneticin and 50 μg / ml hygromycin ) and hek - gqi5 cells stable expressing fpr1 were cultured in ( dmem high glucose , 10 % fbs , 1 % psa , 400 μg / ml geneticin and 50 μg / ml hygromycin ). in general , the day before the experiment , 18 , 000 cells / well were plated in a 384 - well clear bottom poly - d - lysine coated plate . the following day the screening compound - induced calcium activity was assayed on the flipr tetra . the drug plates were prepared in 384 - well microplates using the ep3 and the multiprobe robotic liquid handling systems . compounds were tested at concentrations ranging from 0 . 61 to 10 , 000 nm . results are expressed as ec 50 ( nm ) and efficacy values .