the process of this invention may be utilized for the deallylation of any allyl ester of a carboxylic acid or allyl ether or a phenol , e . g ., allylphenyl ether , the allyl ester of benzoic acid , the allyl ester of cinnamic acid , etc . a preferred class of allyl esters which may be deprotected in accordance with the practice of this invention , are beta - lactam allyl esters such as penicillins , cephalosporins , and carbapenems . particularly preferred are allyl esters of carbapenem derivatives , said derivatives being characterized by a 2 - substituent of the formula ## str1 ## in which a represents a c 1 - c 6 straight or branched chain alkylene group ; r 1 represents an optionally substituted aliphatic , cycloaliphatic , cycloaliphatic - aliphatic , aryl , araliphatic , heteroaryl , heteroaraliphatic , heterocyclyl or heterocyclyl - aliphatic radical and ## str2 ## represents a nitrogen - containing aromatic heterocycle attached to the alkylene group a at a ring carbon atom and quanternized by substituent r 1 . such derivatives are described in detail in u . k . patent application no . gb no . 2 128 187a , the disclosure of which is incorporated herein by reference . the preferred organic - soluble palladium complex catalyst useful in the process of this invention is tetrakis ( triphenylphosphine ) palladium ( 0 ) and it is preferably utilized in the presence of free triphenylphosphine . it is preferred to use from 0 . 01 to 0 . 1 mole of catalyst per mole of allyl ester or ether . it is also preferred to use from 1 . 5 to 5 moles of triphenylphosphine per mole of tetrackis ( triphenylphosphine ) palladium . the amount of pyrrolidine or piperidine used in the reaction is preferably from 1 . 0 to 1 . 5 moles per mole of allyl ester or ether . the deallylation reaction is preferably conducted in an inert solvent such as dichloromethane , chloroform , ethyl ether , benzene , toluene , ethyl acetate , acetonitrile , etc . it is preferred to conduct the reaction at a temperature of from - 5 ° c . to 30 ° c . for a time of from 10 minutes to 4 hours . the following examples illustrate the best modes contemplated for carrying out this invention . ## str3 ## methyl trifluoromethanesulfonate ( 1 . 05 equivalent ) was added to an ice cooled suspension of compound i , obtained as described in step f , example 21 of u . k . patent application no . gb 2128187a , in acetonitrile . after 20 minutes , triphenylphosphine ( 5 % mole ), tetrakis ( triphenylphosphine ) palladium ( 0 ) ( 2 . 5 % mole ) and pyrrolidine ( 1 . 05 equivalent ) were added . precipitation occurred rapidly and the resulting slurry was stirred for 10 minutes at 0 ° c . after adding acetone , the crude solid was isolated and crystallized from methanol to give the desired product , ii , in 70 % yield and with 90 - 93 % purity . when potassium 2 - ethylhexanoate is substituted for pyrrolidine in example 1 , no product is obtained . a solution of the allyl ester , compound iii , ( 0 . 350 g , 0 . 936 mmol ) in 6 ml of dry acetonitrile was cooled at - 5 ° c . and treated with methyl trifluoromethanesulfonate ( 0 . 111 ml , 0 . 983 mmol ). after 15 minutes , a solution of tetrakis ( triphenylphosphine ) palladium ( 0 . 027 g , 25 mol %) and triphenylphosphine ( 0 . 027 g ) was added . after stirring the reaction mixture for 5 minutes , pyrrolidine ( 0 . 082 ml , 0 . 983 mmol ) was added dropwise . a solid slowly began to separate from the resulting brown solution . the mixture was vigorously stirred at 0 ° c . for 20 minutes , then 15 ml of cold ( 0 ° c .) acetone was slowly added and stirring was continued at 0 ° c . for 20 minutes . the resulting suspension was filtered and the residue was washed with cold acetone and then dried to vacuo to give 0 . 345 g of a beige powder . this material was taken up in a small amount of ph 7 phosphate buffer ( 0 . 05 m ) and applied to a short reverse - phase ( c 18 bondapak ) column . elution with h 2 o and lyophilization of the relevant fractions gave 0 . 255 g of a light yellow solid . this material was rechromatographed , as done before , to afford ( after lyophilization ) pure compound iv ( 0 . 195 g , 60 % yield ) as a light yellow solid : 1 hnmr ( d 2 o ) δ8 . 58 , 7 . 83 ( abq , j = 6 . 4 hz , 2h ), 7 . 87 ( s , 1h ), 4 . 32 - 3 . 95 ( m , 2h ), 4 . 22 ( s , 2h ), 4 . 17 ( s , 3h ), 3 . 32 ( dd , j 1 = 2 . 6 hz , j 2 = 6 . 1 hz , 1h ), 3 . 06 - 2 . 93 ( m , 2h ), 2 . 74 ( s , 3h ), 1 . 22 ( d , j = 6 . 4 hz , 3h ); ir ( kbr ) 1757 , 1590 cm - 1 ; uv ( phosphate buffer , ph 7 . 4 ) 296 nm ( ε7446 ). a solution of the allyl ester , compound v , ( 0 . 582 g , 0 . 0015 mol ) in 15 ml of dry acetonitrile was treated with methyl trifluoromethanesulfonate ( 0 . 178 ml , 1 . 575 mmol ) at - 5 ° c . under n 2 . after 15 minutes , a solution of tetrakis ( triphenylphosphine ) palladium ( 0 . 035 g , 2 mol %) and triphenylphosphine ( 0 . 035 g ) in 1 ml of methylene chloride was added , followed after 5 minutes by 0 . 131 ml ( 1 . 575 mmol ) of pyrrolidine . the resulting mixture was stirred at 0 ° c . for 20 minutes and then 30 ml of cold ( 0 ° c .) acetone was added . the mixture was vigorously stirred at 0 ° c . for 15 minutes and then the precipitate was collected by filtration , washed with cold acetone and dried in vacuo to give 0 . 520 g of a beige powder . by diluting the filtrate with ether , another 0 . 041 of the crude product was obtained . the combined solids were dissolved in a small about of ph 7 . 4 phosphate buffer ( 0 . 05m ) and applied to a reverse - phase ( c 18 bondapak ) column . elution with h 2 o and then 2 % acetonitrile - h 2 o afforded , after lyophilization , compound iv ( 0 . 413 g , 76 % yield ) as a yellow solid : 1 hnmr ( d 2 o ) δ8 . 55 , 7 . 76 ( abq , j = 6 . 3 hz , 2h ), 7 . 81 ( s , 1h ), 4 . 4 - 3 . 7 ( m , 2h ), 4 . 19 ( s , 2h ), 4 . 16 ( s , 3h ), 3 . 47 - 3 . 14 ( m . 2h ), 2 . 73 ( s , 3h ), 1 . 24 ( d , j = 6 . 4 hz , 3h ), 1 . 16 ( d , j = 7 . 3 hz , 3h ), ir ( kbr ) 1750 , 1595 cm - 1 ; uv ( phosphate buffer , ph 7 . 4 ) 293 nm ( ε7170 ). to an ice - cooled suspension of the allyl ester , compound vii ( 10 . 00 g , 26 . 7 mmol ) in 100 ml of acetonitrile was added methyl trifluoromethanesulfonate ( 3 . 17 ml , 28 . 05 mmol ). the resulting homogeneous yellow solution was stirred at 20 ° c . triphenylphosphine ( 350 mg , 1 . 33 mmol ) and tetrakis ( triphenylphosphine ) palladium ( 770 mg , 0 . 66 mmol ) in 20 ml of methylene chloride were succissively added , the mixture was stirred 5 minutes and then a solution of pyrrolidine ( 2 . 4 ml , 28 . 05 mmol ) in 15 ml of acetonitrile was added over a 5 minutes period . crystallization occurred and the resulting slurry was stirred at 0 ° c . for 10 minutes . pre - cooled acetone ( 150 ml ) was added and the mixture was stirred 15 minutes . the resultant yellow solid was collected and washed twice with 60 ml of acetone . after drying , the yellow solid was triturated in 50 ml of cold ( 0 ° c .) methanol for 30 minutes . the resultant beige paste was filtered , partially dried , and dissolved in 20 ml of cold water . the resulting mixture was filtered quickly and 100 ml of cold ethanol were added . after stirring at 0 ° c . for about 10 minutes , crystallization occurred and the resulting mixture was stirred 1 . 3 hours more . the solid was collected and dried under high vacuum for 3 hours to obtain compound viii , 4 . 82 g , 51 . 8 % yield . a solution of the allyl ester , compound ix ( 12 . 63 g , 33 . 707 mmol ) in 124 ml of acetonitrile was treated at 0 °- 5 ° c . under a nitrogen atmosphere by adding dropwise methyl trifluoromethanesulfonate ( 4 . 055 ml , 35 . 349 mmol ). the clear yellow reaction mixture was stirred for 15 minutes at 0 °- 5 ° c . to this reaction mixture maintained at 0 °- 5 ° c . was added at once triphenylphosphine ( 429 . 44 mg , 1 . 661 mmol ), followed by a solution of tetrakis ( triphenylphosphine ) palladium ( 959 . 56 mg 0 . 831 mmol ) in 33 ml of methylene chloride . the clear orange reaction mixture was stirred at 0 °- 5 ° c . for 5 minutes . there was then added dropwise a solution of pyrrolidine ( 3 . 03 ml , 33 . 707 mmol ) in acetonitrile ( 41 . 3 ml ). to this clear dark orange reaction mixture , which was stirred 5 minutes at 0 °- 5 ° c ., was added , portion wise and with vigorous stirring , ice - cold acetone ( 250 ml ) followed by anhydrous diethyl ether ( 150 ml ). stirring was continued for 5 minutes at 0 °- 5 ° c ., and the suspension was then filtered quickly under a stream of nitrogen . the solid residue was washed with anhydrous diethyl ether ( 50 ml ) and vacuum dreied to obtain 11 . 05 g ( 33 . 12 mmol , yield 96 . 6 %) of compound x as a crude yellow hygroscopic solid . the solid was dissolved in ice - cold phosphate buffer ( 75 ml ; ph 7 . 0 ) and was washed twice with 50 ml portions of diethyl ether . the aqueous layer was vacuum pumped with stirring for 45 minutes and was purified by reversed phase chromotography . after purification and lyophilization , 9 . 63 g ( 27 . 617 mmol , yield 81 . 0 %) of compound x was obtained . utilizing procedures similar to those described in examples 1 - 5 , the above reactions were conducted . compound xii was obtained in a 72 % yield and compound xiv was obtained in a 61 % yield . the following example illustrates the use of piperidine instead of pyrrolidine in the practice of this invention . the reaction illustrated in example 1 was conducted as follows : to a suspension of the allyl ester , compound i ( 350 mg , 0 . 971 mmol ) in 10 ml of acetonitrile , cooled to 0 ° c ., was added methyl trifluoromethanesulfonate ( 0 . 121 ml , 1 . 068 mmol ). the resulting light yellow mixture was stirred 1 hour and triphenylphosphine ( 25 mg , 0 . 095 mmol ) and tetrakis ( triphenylphosphine ) palladium ( 25 mg , 0 . 0216 mmol ) in 2 ml of methylene chloride were added . piperidine ( 0 . 105 ml , 1 . 068 mmol ) was slowly added and the resulting light orange mixture was stirred at 0 ° c . after 15 minutes , a yellow precipitate formed and stirring was continued for 11 / 2 hours . acetone ( 10 ml ) was added and the resulting slurry was stirred 30 minutes , the solid was filtered and washed with two 10 ml portions of acetone and dried . the resultant product , 230 mg , 70 . 7 % yield , had a purity of about 69 . 4 %. the following example illustrates the process of this invention applied to the deallylation of a cephalosporin . to an ice - cooled solution of the allyl ester , compound xv ( 787 mg , 1 . 828 mmol ), tetrakis ( triphenylphosphine ) palladium ( 0 ) ( 53 mg , 0 . 045 mmol ) and triphenylphosphine ( 50 mg , 0 . 190 mmol ) in 10 ml of methylene chloride was slowly added pyrrolidine ( 0 . 161 ml , 1 . 919 mmol ). the mixture was stirred at 0 ° c . for 25 minutes and was then poured into 10 ml of a diluted solution of sodium bicarbonate ( 383 mg ). after vigorous agitation , the organic phase was separated and extracted again with 10 ml of diluted sodium bicarbonate . the aqueous solution was then acidified to ph 2 . 5 at 0 ° c . with 1n hcl to which 10 ml of methylene chloride had been previously added . the organic phase was separated and the aqueous solution was extracted with another 10 ml of methylene chloride . after drying and evaporation in vacuo , 630 mg of the free acid , compound xvi , was obtained ( 88 % yield ). the following two examples illustrate the deallylation process applied to allyl esters of penicillins . to an ice - cooled mixture of the allyl ester of penicillin - v ( 540 mg , 1 . 38 mmol ) and tetrakis ( triphenylphosphine ) palladium ( 40 mg , 0 . 0345 mmol ) in 10 ml of methylene chloride was added pyrrolidine ( 0 . 121 ml , 1 . 45 mmol ). the mixture was stirred at 0 ° c . for 30 minutes and then extracted with 10 ml of aqueous sodium bicarbonate ( 600 mg ). the solution was then acidified with 5 hcl and extracted portions of methylene chloride . after drying and evaporation in vacuo , 301 mg ( 62 . 3 % yield ) of penicillin - v free acid was isolated as a white solid . the nmr spectrum was consistent with the structure of penicillin - v free acid . to a solution of the allyl ester of penicillin - g ( 1 . 456 g ; 3 . 889 mmol ) in 20 ml of methylene chloride were added tetrakis ( triphenylphosphine ) palladium ( 112 mg , 0 . 097 mmol ) and triphenylphosphine ( 100 mg , 0 . 381 mmol ). after stirring a few minutes , a homogeneous mixture was obtained . the mixture was then cooled down to 0 ° c . and pyrrolidine ( 0 . 341 ml , 4 . 084 mmol ) in 5 ml of methylene chloride was added slowly . the resulting mixture was stirred 15 minutes at 0 ° c . diluted sodium bicarbonate ( 25 ml ), prepared by dissolving 1 . 63 g of sodium bicarbonate in 50 ml of water , and 10 ml of ethyl acetate were added . after vigorous stirring , the aqueous protion was collected . the organic phase was extracted with 25 ml of diluted sodium bicarbonate . the combined aqueous phases were cooled to 0 ° c ., 20 ml of methylene chloride were added and the mixture was acidified to ph 2 with 5 % hcl ( about 14 ml ). the organic phase was collected and the aqueous mixture was extracted with two 25 ml portions of methylene chloride . the combined organic phases were dried , then concentrated in vacuo to give 1 . 22 g ( 93 . 8 % yield ) of white solid penicillin - g free acid . the nmr spectrum was consistent with the structure of penicillin - g free acid . the following two examples illustrate the process of this invention applied to the deallylation of simple aromatic acids . to an ice - cooled solution of the allyl ester of benzoic acid ( 1 . 00 g , 6 . 16 mmol ) in 15 ml of methylene chloride was added tetrakis ( triphenylphosphine ) palladium ( 178 mg , 0 . 154 mmol ). the reaction mixture was stirred until a homogenous solution was obtained . pyrrolidine ( 0 . 540 ml , 6 . 47 mmol ) was added and the resulting mixture was stirred 20 minutes at 0 ° c ., the poured into 20 ml of diluted sodium hydroxide ( 285 mg naoh , 7 . 12 mmol ). the organic phase was decanted and the aqueous solution was washed with 5 ml of methylene chloride . after acidification with 5 % hcl ( about 6 ml ) the benzoic acid produce was extracted with methylene chloride using three 10 ml portions . after drying and concentration in vacuo , there were obtained 730 mg ( 97 % yield ) of benzoic acid which was isolated as a white solid having a melting point of 122 °- 123 ° c . to an ice - cooled solution of the allyl ester of trans cinnamic acid ( 1 . 0 g , 5 . 31 mmol ) and tetrakis ( triphenylphosphine ) palladium ( 0 ) ( 150 mg , 0 . 13 mmol ) in 15 ml of methylene chloride was added pyrrolidine ( 0 . 466 ml , 5 . 58 mmol ). the resulting mixture was stirred at 0 ° c . for 50 minutes . it was then poured into 20 ml of diluted sodium hydroxide ( 5 . 86 mmol naoh ), the aqueous phase was washed with two 15 ml portions of methylene chloride , then acidified with diluted 5 % hcl . the acid was extracted with three 10 ml portions of methylene chloride . the organic phase was then dried over magnesium sulfate and evaporated in vacuo to give 765 mg ( 97 . 2 % yield ) of trans cinnamic acid having a melting point of 133 °- 134 ° c . the nmr spectrum was consistent with the structure of trans cinnamic acid . to a solution of allylphenyl ether ( 1 . 00 g , 7 . 45 mmol ) in 10 ml of methylene chloride were added tetrakis ( triphenylphosphine ) palladium ( 0 ) ( 215 mg , 0 . 186 mmol ), triphenylphosphine ( 215 mg , 0 . 819 mmol ) and pyrrolidine ( 0 . 684 ml , 8 . 198 mmol ). the mixture was stirred at room temperature for 4 hours . the reaction mixture was extracted with two 10 ml portions of 5 % aqueous sodium hydroxide , and the extracts were acidified with concentrated hcl to a ph of about 1 - 2 . the phenol was extracted with three 10 ml portions of methylene chloride , dried over magnesium sulfate and filtered . after concentration in vacuo , there were obtained 625 mg ( 89 . 1 % yield ) of pure phenol . the nmr spectrum was consistent with the structure of phenol .