1656
Anal. Chem. 1986, 58. 1656-1660
(25) Nicholson, C. Dynamics of the Brain Cell Microenvironment, MIT: Boston, MA, 1980. (26) Bidlingmeyer, E. A.; Warren, F. V., Jr. Anal. Chem. 1984. 5 6 , 1582A-1596A. (27) Kirkland, J. J.; Yau, W. W.; Stoklosa, H. J.; Dilks, C. H. J . Chromat o g . Sci. 1977, 75, 303. (28) Weber, S.G.; Purdy, W. C. Anal. Chim. Acta 1978. 700. 531-544. (29) Michael, A. C.; Justice, J. E., Jr.; Neill, D. E. Neurosci. Lett. 1985,56,
365-369.
(30) Wightman, R. M. Anal. Chem. lS81. 53, 1125A-1134A.
RECEIVED for review June 3, 1985. Resubmitted February 20, 1986. Accepted April 2,1986. This work was supported by NSF Grants BNS 8210773 and 8509576 and the Emory University Research Fund.
Determination of Fentanyl and Related Compounds by Capillary Gas Chromatography with Electron Capture Detection J a m e s M. Moore,* Andrew C. Allen,' Donald A. Cooper, a n d S u s a n M. C a r r
Special Testing and Research Laboratory, Drug Enforcement Administration, 7704 Old Springhouse Road, McLean, Virginia 22102-3494
A method has been developed that allows for the differentlation and quantltatlon of fentanyl and 25 analogues and homologues In ifflclt preparations. After isdatlon from the sample matrlx, the fentanyl compound is sublected to derlvatlratlon wlth heptafluorobutyrlc anhydride In the presence of 4(dhnethylamlno)pyrldie. Mosl fentanyls yielded two derlvatiratlon products, both vlnylogous amldes. Upon chromatographic analysis an addltlonal compound, belleved to be an injectlon port thermal elkninatkn product, was produced. By use of these three chrornatographlc peaks, the malority of fentanyls studied could be easily differentiated. Accurate quantitative results and good reproduciblllty were achieved at fentanyl levels of between 0.001 and 1% w/w. All fentanyls yielded heptafluorobutyryl derivatives that were easlly detected on-column at low picogram levels using a nonpolar fused dllca caplllary column In the splltless mode Interfaced wlth a 83Nielectron capture detector.
Fentanyl, N - [1-(2-phenethy1)-4-piperidyl]propionanilide, is a narcotic analgesic of the 4-anilidopiperidine series. Clinically, it has a potency approximately 100 times that of morphine ( I ) . In recent years, the appearance and subsequent abuse of compounds closely related to fentanyl have been of growing concern to law enforcement officials. Since the late 1970s, 10 homologues and 6 analogues of fentanyl, including a-methylfentanyl and 3-methylfentanyl, have appeared on the illicit market. Some have been implicated in overdose deaths, especially on the west coast of the United States. The analogues and homologues of fentanyl are often encountered on the illicit market in highly adulterated dosage forms at levels of between 0.1 and 1% w/w. Thus, there is an ever-increasing need for the development of methodology that will allow for the rapid screening and low-level quantitation of these compounds. Recent studies have primarily utilized high-performance liquid chromatography (HF'LC) and gas chromatography-mass spectrometry (GC-MS) to accomplish these analyses (2-9). We describe here methodology that is very sensitive and highly specific for the detection of fentanyl and related compounds. Furthermore, our studies indicate that accurate Present address: Western Regional Laboratory, Drug Enforcement Administration, 450 Golden Gate Ave., Box 36075, San Francisco, CA 94102.
quantitative results can be achieved between levels of 0.001 and 1%w/w (based upon 100-mg sample weight). The procedure involves isolation of the fentanyl from the sample matrix followed by derivatization with heptafluorobutyric anhydride (HFBA) in the presence of 4-(dimethylamino)pyridine (4-DMAP). The two major products resulting from this derivatization are both vinylogous amides, a structural feature that allows easy isolation and also accounts for good product stability in solution. Upon chromatographic injection in the splitless capillary mode, a chromatographic peak resulting from the thermal degradation of one of the vinylogous amide products is produced. The thermal degradation and vinylogous amide peaks exhibited good chromatography at low picogram levels when chromatographed on a nonpolar fused silica capillary column. When these peaks are used, the methodology has proven effective for the differentiation of fentanyl and 25 of its analogues and homologues. We have also applied this procedure for the sensitive detection of N-(2-phenethyl)-4-phenyl-4-acetoxypiperidine (PEPAP), a substance that is structurally similar to a compound that has been implicated in producing Parkinsoniantype symptoms in its users. Owing to the high sensitivity and specificity of this methodology, we believe it also has potential application in toxicological analyses. EXPERIMENTAL SECTION Instrumentation. Low-resolution mass spectra were acquired on a Finnigan MAT Model 4630 quadrupole mass spectrometer. The GC-MS was fitted with a 12-m X 0.25-mm-i.d. fused silica capillary column coated with DB-5 (J & W Scientific,Inc., Rancho Cordova, CA) at a film thickness of 0.25 pm. Sample injection was accomplished with an on-column injector (J & W Scientific) at a helium carrier gas velocity of 60 cm/s. Data were acquired at an ionization potential of 60 eV and sourve temperature of 120 "C. Both positive and negative ion (electron capture) chemical ionization utilized methane reagent gas at a filament potential of 100 eV. For positive ion chemical ionization, the source temperature was maintained at 140 "C and a source pressure of 0.35 torr (uncorrected) existed. Negative ion data were acquired at a source temperature of 80 "C and a pressure of 0.5 torr. High-resolution mass spectral data were obtained with a Finnigan MAT Model 8230 (San Jose, CA) double-focusingGC-MS operating at an ionization potential of 70 eV. Sample introduction was accomplished with split mode injection (Grob-type injector) into a 30-m x 0.25-mm fused silica capillary column coated with DB-1 (J & W Scientific) at a film thickness of 0.25 pm. Source temperature was approximately 150 "C and data were acquired at a resolution of 10000 (5% valley).
This article not subject to U S . Copyright. Published 1986 by the American Chemical Society
ANALYTICAL CHEMISTRY, VOL. 58, NO. 8, JULY Table I. Structural Formula for Fentanyl and Related Compounds
1986
1657
p,d-DDT
' I
I
1
compd 1 2
3 40
5 6 7 8" 9
R6
CHZ CHZ CHzCHCH3 CHZCHCH3 CHgCHCH?
m-F 0-F m-F
10 1l a 12
13 14 15 16b 17 18 19
20" 21 22
23 24 25" 26
P-F m-CH3 CHiCH; m-CH3 CHzCH3 CHZCHz CH&H,
CH3 o-CH~ P-CH3
CH,CH3 m-CH3 CH3 m-CH3 CH2CH2 CHZCH3 CHzCH3 o-CH3 CHzCH3 P-CH3 CHZCH3 CH3 CHzCH3 CHzCH3 CH~CH~CH~
" Compounds encountered in case samples. Fentanyl. Nuclear magnetic resonance ('H NMR) spectra were obtained on a Nicolet (Fremont, CA) 200-MHz spectrometer interfaced with an 1180 data system and 293A pulser. Gas Chromatography-Electron Capture Detection. All chromatograms were generated in the splitless mode on a Hewlett-Packard (Avondale,PA) 5880A gas chromatograph fitted with a 15-m X 0.25-mm-i.d. fused silica capillary column coated with DB-1 (J & W Scientific) at a film thickness of 0.25 pm. The GC was equipped with a e3Nielectron capture detector (15 mCi) and interfaced with a Hewlett-Packard Level IV data processor. Injector and detector temperatures were maintained at 275 "C and 300 "C, respectively. The oven temperature was multilevel programmed as follows: (level 1) initial temperature, 90 OC; initial hold, 5.0 min; temperature program rate, 25 "C/min; final temperature, 160 "C; final hold, 1.0 min, (level 2) temperature program rate, 4 "C/min; final temperature, 275 "C; final hold, 10 min. Ultra-high-purity hydrogen (Air Products, Tamaqua, PA) was used as the carrier gas at a linear velocity of 35-45 cm/s. An argon/methane (95/5) mixture was used as the detector makeup gas at a flow rate of about 30 mL/min. The injector liner was fused silica (Hewlett-Packard), and the senta were Thermogreen LB-1 (Supelco, Inc., Bellefonte, PA). The illustrated chromatograms were recorded at an attenuation of 2' and at a chart speed of 0.75 cm/min. During the splitless injection, the solvent was vented after a 1.0-min hold. Reagents. The 4-DMAP was obtained from Alfa Products (Danvers, MA). Isooctane, acetonitrile (ethanol-free), and diethyl ether (ethanol- and peroxide-free) were Distilled in Glass products of Burdick and Jackson Laboratories (Muskegon, MI). HFBA, supplied in 1-mL sealed ampules, was obtained from Pierce Chemical Co. (Rockford, IL). All other chemicals were of reagent grade quality. Standards. Fentanyl and its analogues and homologues were prepared by using previously described syntheses (10-21). Their structures are illustrated in Table I. The internal standards p,p'-DDT, aldrin, and dieldrin were products of Supelco, Inc. Dioctyl phthalate (DOP) was obtained from Aldrich (Milwaukee, WI).
I
0
5
{O
1'5
20
d5
d0
d5
MINUTES
Figure 1. Capillary chromatogram of a mixture of fentanyl and compound 26 after derivatization with HFBA in the presence of CDMAP: peaks 3 and 4 are the fentanyl derivatization products B and A, respectively, (see Scheme I and Table 11); peaks 3' and 4' are the compound 26 analogous derhratization products B and A, respectively; peaks 1 and 1' are the GC thermal elimination of product B for fentanyl and compound 26, respectively (see Scheme I); amount injected oncolumn = ca. 8 ng (relativeto weight of precursor fentanyl);p ,p'-DDT
=400 pg.
Preparation and Derivatization of Standard Fentanyl and Standard Compound 26. An acetonitrile solution of fentanyl (compound 16) and compound 26 was prepared at a concentration of 1.0 mg/mL. To a 1.0-mL aliquot of the acetonitrile solution in a 13-mL conical centrifuge tube was added 50 mg of 4-DMAP and 50 pL of HFBA. After solubilization, the derivatization was allowed to proceed for 1 h at 75 "C. After cooling, 5.0 mL of isooctane (containing 200 pg/pL of p,p'-DDT and 10 ng/pL of dioctylphthalate) and 5 mL of an aqueous, 1 N sodium carbonate solution were added to the tube. The tube wa, shaken vigorously for 5-10 s and then centrifuged. A 1.0-mL aliquot of the isooctane layer was diluted to 50.0 mL with additional isooctane (containing internal standards). A 5-mL aliquot of the final isooctane dilution was placed in a 13-mL conical centrifuge tube and back-extracted with 5 mL of 1N sulfuric acid. After centrifugation, about 2 pL of the isooctane layer was injected into the GC under conditions described previously. The chromatogram of this mixed standard is illustrated in Figure 1. Sample Analysis. (a) Unadulterated Samples. An amount of sample is dissolved in acetonitrile (containing 0.10 mg/mL of compound 26 as internal standard) to yield a concentration of about 0.1 mg/mL. A 1.0-mL aliquot of the acetonitrile solution is treated as described above for the standards, except the final isooctane dilution (containing internal standards) is 10.0 mL. After chromatographic analysis and review of retention data given in Table 11, an equivalent amount of the appropriate standard is selected and treated in a similar manner. ( b )Samples Adulterated with Sugars. An amount of sample equivalent to about 0.1 mg of the fentanyl is placed in a beaker and dissolved in 2 mL of water. To the solution is added 100 pL of an aqueous solution containing 1.0 pg/pL of compound 26 as internal standard. The solution is rendered basic by the addition of a small amount of sodium carbonate. To the beaker is added 3 g of acid-washed Celite 545 (J.T. Baker Chemical Co., Jackson, TN). After thorough mixing, the contents of the beaker are transferred to a glass chromatographic column (270 mm X 25 mm) and firmly packed over a layer consisting of 0.5 mL of aqueous 1 N sodium carbonate and 1 g of acid-washed Celite 545. The column is eluted with water-saturated ethyl ether, and the first 5 mL of the eluate is collected in a 13-mL conical centrifuge tube. The ether eluate is evaporated gently to dryness on a steam bath under a current of nitrogen. To the residue is added 1.0 mL of acetonitrile, and then it is treated as described above for the standards beginning with "...was added 50 mg of 4-DMAP.-", except the final dilution with isooctane (containing internal standards) is 10.0 mL. After chromatographic analysis and review of retention data given in Table 11, the appropriate standard is selected and treated as described above for the standards.
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ANALYTICAL CHEMISTRY, VOL. 58, NO. 8, JULY 1986
Scheme I
Table 11. Capillary GC Retention Times for Fentanyl and Related Compounds
A
\@
retention times." min
7
FENTANYL CH2CN 4-DUAP HFBA
I
4
75OC
/'\
fi
A
compd
peak 1
1 2 3 4 5 6 76 8 9'
12.14 12.14 13.68 13.68 13.84 13.48 13.48 13.48 13.48 15.00 13.48 13.48 14.98 14.45 13.50 13.48 13.48 14.74 13.47 15.76 14.44 13.48 13.47 14.74 14.54 15.74
10 11
PRODUCT (PEAK #3) -
PRODUCT A (PEAK # 4 )
(80% y i e l d )
( 2 0 % yield)
GC _ TkERMAL _ _ _ _ELIMINATION __-
PRODUCT
(PEAK itl)
Quantitative results are calculated in the usual manner using internal standard compound 26.
RESULTS AND DISCUSSION Reaction of Fentanyl with HFBA. Scheme I illustrates the reaction of fentanyl with HFBA in the presence of 4DMAP. We have previously reported this unusual oxidation for narcotine (22). In that work it was shown that the reaction does not proceed in the absence of base or even in the presence of pyridine. High-yield derivatization requires the presence of a base such as 4-DMAP, suggesting the effective oxidizing and acylating species to be the N-(heptafluorobutyryl)-4(dimethy1amino)pyridinium ion (23). The reaction yields two major products, A and B (Scheme I), both vinylogous amides. The formation of two products is not entirely surprising in that hydrogens on the a-carbon and C-2 are both available for hydride abstraction. It is believed that product B predominates because of the more restricted geometry associated with the piperidine ring, hence maintaining that conformation necessary for the reaction to proceed. The approximate yields for both products were determined by GC-ECD, GC-MS, and 'H NMR. Figure 1 illustrates the chromatography of products A (peaks 4 and 4') and B (peaks 3 and 3') for fentanyl (peaks 3 and 4) and compound 26 (peaks 3' and 4'). The relationship between derivatization yield at 75 "C and reaction time was studied. Minimum reaction times (5-10 min) resulted in a much decreased yield for both products A and B. A reaction time of 1 h appeared optimum. Longer reaction times, e.g., 12 h, did not enhance the derivatization yield and did not favor the formation of product B relative to product A. Due to their amide-like properities, products A and B were found to be stable in isooctane for at least several days. This is in contrast to 0-HFB derivatives, which exhibit accelerated decomposition when left in solution. The vinylogous amide character of products A and B allow for their ready isolation from excess 4-DMAP as well as other tertiary amines. Chromatography, Response, and Reproducibility. Table 11lists retention times for fentanyl (compound 16) and 25 analoguea and homologues. All fentanyls are listed in order of ascending retention time for the last major peak (peak 4, product A).
12 13d 14 15O 16 17 18 19 20 21 221 23 24 258 26
peak 2
16.82 16.83 18.50 18.50
16.82
18.50
peak 3
peak 4
25.32 26.04 27.24 27.94 28.12 26.60 26.20 27.20 27.30 28.90 27.32 28.07 28.73 28.30 27.98 27.90 28.54 28.64 28.69 29.07 29.01 28.59 29.16 29.29 29.97 29.70
27.46 28.12 28.29 28.62 28.78 29.33 29.56 29.70 29.90 29.96 30.01 30.08 30.28 30.28 30.40 30.46 30.80 30.81 31.00 31.12 31.26 31.36 31.50 31.72
OPeaks 1 and 2 adjusted for p,p'-DDT retention time of 18.00 min; peaks 3 and 4 adjusted for dioctyl phthalate retention time of 22.25 min. *Other peaks, 13.94 min. Cother peaks, 13.94 min. dother peaks, 13.02, 24.32 min. e Other peaks, 14.20 min. 'Other peaks, 14.18 min. gother peaks, 27.21, 28.02 min. Aldrin and dieldrin internal standards, 12.00 and 15.00 min, respectively. Upon derivatization, extraction, and GC injection, most fentanyls studied yielded three chromatographic peaks. As discussed previously, peaks 3 and 4 represent synthetic products B and A, respectively (see Scheme I, Figure 1,and Table 11). Peak 1 is believed to result from the GC injection port decomposition of product B (see Scheme I). Support for this observation can be found in the fact that this peak is not detected if the reaction products are injected in the on-column mode as opposed to the splitless mode. Furthermore, the intensity of peak 1 increased more rapidly (relative to peaks 3 and 4) with increasing splitless injection port temperature. Finally, its appearance in the chromatograms of compounds 1and 2 (Table 11) suggests that it is derived from product B, as these fentanyls yield only this synthetic product. Peak 1 is of special diagnostic value in that it allows for the differentiation of fentanyls with substitution on ring A and the propanamide moiety as opposed to substitution on ring B, aand 8-carbons, and the piperidine ring. This is illustrated for peak 1 retention times of compounds 1, 3, 6, 9, 14, 25, and 26 (see Tables I and 11). Inspection of Table I1 reveals that some fentanyls yield fewer than three chromatographic peaks while some give four or more. Thus, compounds 1 and 2 exhibit only two peaks (peaks 1and 3, product B), because the formation of product A is not possible. Compounds such as no. 25 can yield more than three peaks, due to cis and trans isomerism or different positions for the endocyclic double bond. The appearance of peak 2 for some fentanyls has yet to be rationalized. By use of all peaks associated with the fentanyls listed in Table 11, their differentiation is easily accomplished. To determine on-column minimum detectable quantities (MDQ), we subjected a mixture of fentanyl (100 pg) and compound 26 (100 pg) to derivatization, followed by isooctane extraction and serial dilution with isooctane followed by GC
ANALYTICAL CHEMISTRY, VOL. 58, NO. 8, JULY 1986
1659
Table 111. Reproducibility of Fentanyl (Compound 16) and Compound 26: Derivatization, Isooctane Extraction, and Chromatography
fentanyl/compd 26 (peak area/peak area): % amt derivatized, r g
peak 1
peak 3
peak 4
1 10 100 1000
5.19 1.72 2.27
3.71 0.67 0.71 1.19
6.96 2.80 0.99 3.18
a
4.50
Coefficient of variation (n = 7).
injection. At a GC attenuation of 23 we determined the MDQ for peaks 3 and 4 to be between 10 and 20 pg, and for peak 1, 20-40 pg (based upon weight of precursor fentanyl). The reproducibility of the chromatographic peaks for fentanyl and compound 26 was studied in terms of derivatization, isooctane extraction, and chromatographic response. A mixture of fentanyl and compound 26 at concentration levels of 1, 10, 100, and 1000 pg/mL of acetonitrile was subjected to derivatization, extraction, and chromatographic injection. The analysis was repeated seven times for each concentration level, and peak area ratios of fentanyl/compound 26 for peaks 1, 3, and 4 were calculated. Coefficients of variation were determined for each peak and are given in Table 111. The results in Table I11 reveal good reproducibility for the concentration range studied. In all cases, peak 3 (product B, Scheme I and Figure 1)yielded the most reproducible results. For this reason, it was utilized for subsequent quantitative analyses. Sample Analysis and Presumptive Identification. Illicit fentanyl samples encountered in the laboratory are often adulterated with sugars or other drugs, rendering concentration levels of well below 1%w/w. Samples can also be contaminated with reaction byproducts, such as secondary amines. For simple fentanyl-sugar mixtures, the method described herein is effective in isolating the fentanyl for derivatization. For samples contaminated with significant amounts of secondary amine synthetic byproducts, an ion-pair “cleanup”is sometimes desirable. We have observed that most fentanyls are readily extracted from dilute hydrochloric acid into chloroform as cation-chloride ion pairs (24). Conversely, most secondary amines are retained in the aqueous phase. Thus, a recent seizure of a mixture of four thiophene-type fentanyl analogues contaminated with secondary amine impurities was subjected to ion-pair “cleanup”. After derivatization and isooctane extraction of the isolated fentanyls, this sample gave the chromatogram illustrated in Figure 2. In order to more fully evaluate the qualitative and quantitative aspects of the methodology, 10 fentanyls from Table I were selected on a “blind” basis and subjected to analysis. Five of the fentanyls were “uncut” and five were adulterated with sugars to concentrations levels between 0.001 and 1% w/w. In all cases, the appropriate fentanyl was correctly identified. The results also indicate that the methodology is suitable for quantitative purposes, as evidenced by the data given in Table IV. For accurate quantitation, compensation must be made for any anomalies associated with (a) the isolation of the fentanyl from the sample, (b) derivatization, (c) isooctane extraction, and (d) chromatography. For this reason, the use of an appropriate internal standard is mandatory. Inspection of retention data given in Table I1 reveals compound 26 to be an ideal choice. Furthermore, we have yet to detect this fentanyl in illicit samples. The use of compound 26 as an internal standard has proven to be effective in providing accurate and reproducible quantitative results (Tables I11 and IV). Com-
b
5
IO
1’5 io MINUTES
is
50
35
N-t1-(2-(2-thienyl)ethyl)-4-piperidyl]-N-phe~ylpropanamide
Flgure 2. Capillary chromatogram of an illicit sample containing a
mixture of four thiophene analogues of fentanyl. The following mixture was subjected to ion-par “cleanup” followed by derivatization with HFBA in the presence of 4-DMAP: (a) N - [ l-(l-methyC2-(2-thienyl)ethyl)-4-piperidyl]-N-phenylpropanamide, (b) N - [ 1-(2-(BthIenyl)ethyl)-4-piperidyl]-N-phenylpropanamide, (c) N - [ 1-(2-(24hIenyl)ethyl)-4-(cisItrafts -bmethylpiperidyl)]-N-phenylpropanamide, and (d) N - [ 1-(2-thlenyl)methyl-4-piperldyl]-N-phenylpropanamide.
Table IV. Quantitative Analysis of Fentanyls
amt added, pg sugar,
compd 17 23 18 24 22 a
(pg/100 mg of %)
1.00 (0.0010) 10.0 (0.010) 36.0 (0.036) 100.0 (0.100) 1000.0 (1.00)
amt found,” pg (rg/100 mg of sugar, % ) 1.14 (0.0011) 11.0 (0.0110) 34.8 (0.035) 76.2 (0.076) 1082.6 (1.08)
Average of dudicate analvses.
pound 26 was prepared as described in the Experimental Section. It should be emphasized that when a structurally nonrelated internal standard, such as p,p’-DDT, was used, reproducibility and accuracy suffered significantly. Spectral Characterization. The mass spectra of derivatization products A and B for fentanyl (Scheme I) were acquired. The assignment of structures was accomplished via the interpretation of mass spectral data and the knowledge that both products A and B are neutrals. To obtain neutral extraction characteristics, as found in products A and B, requires either the excision of the basic nitrogen from the fentanyl molecule or the introduction of an HFB moiety at some site in the molecule such that the basic nitrogen is converted to one having amide character. Positive and negative ion detection chemical ionization mass spectrometry confirmed a molecular weight for both products A and B to be 530. The even molecular weight confirms the presence of an even number of nitrogens and negates the possibility of basic nitrogen excision. If products A and B were a fentanyl-4-DMAP adduct an even number of nitrogens would also be present. However, such a product would most assuredly be a base and is, therefore, discounted as a possibility. Given the molecular weights of products A and B less the molecular weight of fentanyl, one obtains a difference of 194 amu. This difference would correspond to the introduction of HFB and a double bond into the fentanyl molecule. It then follows that
1660
ANALYTICAL CHEMISTRY, VOL. 58, NO. 8, JULY 1986
X at m / z 382.1045 (theoretical value = 382.1042), Y at mlz 290.0413 (theoretical value = 290.0416),and Z at m/z 105.0705 (theoretical value = 105.0704) (Scheme 11). The 'HNMR analysis of fentanyl derivatization products A and B yielded data that were consistent with the assigned structures. Registry No. 1, 1237-52-1; 2, 1474-02-8; 3, 101860-00-8; 4, 79704-88-45,79146-56-8;6,93736-21-3; 7,90736-20-2;8,325884-2; 9, 90736-22-4; 10, 90736-13-3; 11, 90736-23-5; 12, 1640-10-4; 13, 42045-77-2; 14, 90736-14-4; 15, 90736-11-1; 16, 437-38-7; 17, 90736-12-2; 18, 90736-15-5; 19, 47480-47-7; 20, 90736-10-0; 21, 90736-17-7; 22, 2141-47-1; 23, 1838-67-1; 24, 90736-18-8; 25, 42045-86-3; 26, 59708-54-2.
Scheme I1
Al?
I
i ,--.
U HFB
U
"o--L+NP(FB
'
X
v
LITERATURE CITED
Z I
HFB
W the double bond must be introduced between the carbons a and /3 to the piperidine nitrogen, and the HFB must be at a @-carbon,in other words products A and B. During previous work in this laboratory, it has been ascertained that the introduction of HFB into a piperidine ring occurs much more readily than in a 2-phenethyl moiety. It would therefore be reasonable to assign the structure for product B to the compound producing chromatographic peak 3 (Figure l),as it is the most abundant. Conversely, the least abundant compound should be product A and, therefore, be responsible for peak 4. Confirmation for these assignments was obtained from GC-MS data with electron ionization providing the most useful data. The elemental composition of all significant ions was determined by exact mass measurements. For product A, these included ions V at m / z 381,0953 (theoretical value = 381.0963) and W at m / z 212.1076 (theoretical value = 212.1075) (Scheme 11). For product B, these included the molecular ion at m / z 530.1832 (theoretical value = 530.1804) and ions U at m / z 473.1468 (theoretical value = 473.1464))
(1) Finch, J. S.; DeKornfeM, T. J. J. CUn. pharmacal. 1887, 7 , 46. (2) Ailen, A. C.; Cooper, D. A.; Kram. T., unpublished work, Drug Enforcement Adrninlstration: McLean. VA, 1983. (3) Heagy, J. A., unpublished work, Drug Enforcement Administration, Western Laboratory: San Franclsco, CA, 1981. (4) Kram, T. C.; Cooper, D. A.; Allen, A. C. Anal. Cbem. 1881, 53, 1379a. (5) Cooper, D. A.; Allen, A. C.; Lurk, I. S., unpublished work, Drug Enforcement Administration: W e a n , VA, 1981. (6) Cheng, M. T.; Kruppa, G. H.; McLafferty, F. W.; Cooper, D. A. Anal. Cbem. 1882, 54, 2204. (7) Allen, A. C.; Lurie, I . S., unpubllshedwork, Drug Enforcement Admlnistratlon: McLean, VA, 1984. (8) Lurie, 1. S.;Ailen, A. C.; Isaaq, H. J. J. Liq. Chromatogf. 1884, 7(3), 463. (9) Lurie, I. S.; Ailen, A. C. J. Cbromatogr. 1884, 202, 283. (10) Riley, T. N.; Bagley, J. R. J. Med. Cbem. 1878, 22(10), 1167. (1 1) Van Bever, W. F. M.; Nlemegeers, C. J. R.; Janssen, P. A. J. J . Med. Chem. 1874, 17(10), 1047. (12) Maryanoff, B. E.; McComsey. D. F.; Taylor, R. J., Jr.; Gardock, J. F. J. Med. Chem. 1881, 24 (I), 79. (13) Lobbezoo, M. W.; Soudijn, W.; Van Wijngaanden, I. J . Med. Chem. 1081, 24 (7), 777. (14) Riley, T. N.; Hale, D. B.; Wilson, M. C. J. pharm. Sci. 1873, 62 (6), 963. (15) Maryanoff, B. E.; Simon, E. J.; Gioannini, T.; Gorissen, H. J . Med. Cbem. 1882, 25 (E), 913. (16) Lednicer. D.; Mitscher, L. A. The Organic Chemistry of Drug Syntbesls; Wlley: New York, 1977; p 298. (17) Riley, T. N.; Hale, D. B. U S . Patent 3923992, May 3, 1974. (18) Archbald, J. L. British Patent 141 1 782, Oct 29, 1975. (19) Riley. T. N.; Hale, D. B. b r m a n Patent 2522785. Nov 27, 1975. (20) Janssen, P. A. J. French Patent 1517 670, March 22, 1968. (21) Archlbald. J. L. British Patent 141 1783, Oct 29, 1975. (22) Moore, J. M.; Akn, A. C.; Cooper,D. A. Anel. Cbem. 1984, 56, 642. (23) Hofmann. H.; Meyer, 8.; Hofmann, P. Angew. Cbem., Int. Ed. fngl. 1872, 1 1 , 423. (24) Cooper, D. A.; Jacob, M.; Allen, A. C. J . fwensic Sci., in press.
RECEIVED for review December 2,1985. Accepted March 10, 1986.
