Notes 1,8-dichloroanthracene. The 9-anthraldehyde was eluted from the column with THF: yield 9 g; mp 224-226” (THF). Anal. (C15HsC1zo) C, H. 1,5-Dichloro-9-anthraldehyde.Formylation of 34.4 g of 1,5dichloroanthracene with 20.2 g of a,a-dichloromethyl methyl ether as detailed in the preceding preparation yielded 3 g of the titled compound, mp 188-190” (PhH-heptane). Anal. (Ci5HsC120) C, H, C1.
Journal of Medicinal Chemistry, 1974, Vol. 17, No. 5 565 e d into this molecule (compared t o a - m e t h y l d o p a ) was t h e possible cause of t h e biological inactivity. Rastogi, et ~ l . prepared , ~ an analogous tetralin a m i n o acid 3 a n d found n o hypotensive effect a n d n o i n uitro inhibition of D o p a decarboxylase. Neither t h e Taylor nor the Rastogi group described the Dopa decarboxylase inhibition test which was employed.
A c k n o w l e d g m e n t . T h e a u t h o r wishes t o express gratit u d e t o Dr. R. E. S t r u b e for t h e encouragement of this work a n d t o t h e U. S. Army Medicinal Research a n d Development C o m m a n d for their financial support. T h i s work was performed under Contract No. DADA17-71-C1038 a n d is Contribution No. 1217 from t h e Army Fksearch Program o n Malaria.
1
2
References (a) P. Chien, D. J . McCaustland, W. H. Burton, and C. C. Cheng, J . Med. Chem., 15, 28 (1972);(b) W. T . Colwell, V. Brown, P. Christie, J. Lange, C. Reece, K. Yamamoto, and D. W. Henry, ibid., 15, 771 (1972);(c) E. A. Nodiff, A. J. Saggiomo, M. Shimbo, E. H. Chen, H. Otomasu, Y. Kondo, T . Kikuchi, B. L. Verma, S. Matsuura, K. Tanabe, M. P. Tyagi, and S. Morosawa, ibid., 15,775(1972). (a) F. Y. Wiselogle, “A Survey of Antmalarial Drugs: 19411945,”3. W. Edwards, Ed., Ann Arbor, Mich., 1946; (b) G. R. Coatney, W. C. Cooper, N. B. Eddy, and J. Greenberg, “Survey of Antimalarial Agents,” Public Health Monograph No. 9, Washington, D. C., 1953,p 182; (c) E. L.May and E. Mossettig, J . Org. Chem., 11, 353 (1946);(d) E. L. May and E. Mossettig, J. Amer. Chem. SOC.,70,686 (1948). W. G. Duncan, W. T. Colwell, C. R. Scott, and D. W. Henry, J. Med. Chem.. 11.1221 (1968). (4) R. E.Strube, Amkoalcohol Antimalarial Conference, Walter Reed Army Institute of Research, Washington, D. C., May 1969. (5) J . T. Traxler, E. P. Lira, and C. W. Huffman, J . Med. Chem., 15,861 (1972). (6) See ref 2 and E. A. Steck, “The Chemotherapy of Protozoan Diseases,” Vol. 111, Division of Medicinal Chemistry, Walter Reed Army Institute of Research, 1971,p 23.65. (7) S. Kaimatsu, I. Hiramo, and T . Tanabe, Chem. Abstr., 23, 4696 (1929). (8) 0.Fischer and A. Sapper, J . Prakt. Chem., [2] 83, 201 (1911). (9) T. L. Jacobs, S. Winstein, J. Ralls, J. H. Robson, R. B. Henderson, R. Akawie, W. Florsheim, D. Seymour, and C. Seil, J. Org. Chem., 11, 21 (1946);(b) K. N. Campbell and J. F. Kerwin, J. Amer. Chem. SOC.,68, 1837 (1946);( e ) D.R. V. Golding and W. H. McNeely, ibid., 68,1847 (1946). (IO) H. Gross and J. Rusche, Chem. Ber., 99,2625(1966). (11) T . S. Osdene, P. B. Russell, and L. Rane, J. Med. Chem., 10,431(1967). (12)R. Golden and L. M. Stock, J. Amer. Chem. SOC.,94, 3080 (1972).
R i g i d A m i n o A c i d s Related to a - M e t h y l d o p a Joseph G. Cannon,* John P. O’Donnell, John P. Rosazza, and Charles R. Hoppin Division of Medicinal Chemistry and Natural Products, College of Pharmacy, The University of Iowa, Iowa City, Iowa 52242. Received December 17. 1973 T h e antihypertensive activity of a - m e t h y l d o p a (1) has prompted numerous workers t o incorporate t h e salient features of this molecule into a rigid framework. Taylor, et ul.,I prepared a n i n d a n derivative 2 a n d its dimethyl ether, b o t h of which were inactive in an in viuo screen for hypotensive activity. T h e compounds were likewise inactive in in uitro screens against D o p a decarboxylase, a n d i t was concluded t h a t t h e rigidity a n d s y m m e t r y incorporat-
3 T h e dramatically high order and wide spectrum of biological effects produced by 2-dimethylamino-5,6-dihydroxytetralin (4),3,4 as compared with t h e 6,7-dihydroxy syst e m 5,t suggested t h a t molecular rigidity per se might n o t b e t h e critical p a r a m e t e r for biological effect b u t that t h e arrangement of t h e OH functions o n t h e aromatic ring is critical.
HO
I
R‘ 4, R = R ’ = M e 9, R = R ’ = H
6
5
HO
HO
NHY 7
8
It was speculated that t h e OH group disposition i n 2 a n d 3 might b e d e t r i m e n t a l t o maximal a - m e t h y l d o p a like effects, a n d accordingly t h e i n d a n a n d tetralin syst e m s 6 and 7 were selected for preparation and biological study. T h e s e systems are, like 2 and 3, rigid analogs of a methyldopa, b u t t h e y represent different frozen rotamers of it. Attention was limited i n the present work t o in uitro effects of t h e a m i n o acids on Dopa decarboxylase. Compounds 6 and 7 were prepared from t h e corresponding ketones b y literature modifications of t h e Strecker reaction. Preparation of t h e a m i n e s 8 a n d 9 (which are decarboxylation products of 6 a n d 7) has been described i n prior c o m m ~ n i c a t i o n s however, ;~~~ in t h e present work, t h e dimethyl ether of 9 was synthesized from t h e appropriate p-tetralone b y conversion t o its 0 - m e t h y l oxime a n d reduction of this with diborane. Overall, this sequence represents a m a r k e d improvement over t h e literature one. Spectral (ir a n d n m r ) data on all compounds t J. P. Long, University of Iowa, unpublished data.
Table I. Inhibitors of D o p a DecarboxylaseQ 3
x
70-~ inhibition 10-4
3
x lo-J
3
x 10-2
Inhibitor
M
M
M
Caffeic acid dl-a-Methyldopa 3 6 7
33
66 66 33 100 100
100 100 100 100
33 0
0 0
100
Incubations were conducted as described in t h e Experimental Section. All compounds listed in the table were preincubated with t h e enzyme a n d pyridoxal 5-phosphate for 15 min before L-Dopa ( 3 X M final concentration) was added t o complete the reaction mixtures. Incubations were conducted for 30 min. prepared were consistent with t h e proposed structures. Biological. Aromatic L -amino acid decarboxylase (Dopa decarboxylase) was used to evaluate t h e ability of 3, 6, a n d 7 t o serve either a s substrates for the enzyme or a s inhibitors of t h e enzymatic decarboxylation of L-dopa. When these a - m e t h y l d o p a analogs were incubated with the enzyme, none of t h e respective a m i n e products3 could be conclusively detected on chromatograms, while s t a n d a r d incubation mixtures converted 8.95 pmol of L-dopa into dopamine in 1 hr. It h a d been anticipated t h a t the rates of conversion of 3, 6, a n d 7 into their respective a m i n e s would be m u c h slower t h a n the conversion of L-dopa into d o p a m i n e ; t h e rate of conversion of a - m e t h y l d o p a into a methyldopamine h a s been shown6 t o be approximately 'boo t h a t of L-Dopa. E n z y m e incubations were conducted with 2, 10. a n d 20 times t h e s t a n d a r d a m o u n t of enzyme, a n d incubations were allowed t o proceed with 3, 6, or 7 for as long as 24 h r , b u t no detectable a m o u n t s of t h e a m i n e products resulted. It should be noted t h a t dl-3, 6, a n d 7 were employed in t h e enzyme studies; racemic a m i n o acids have been reported6 t o be substrates for aromatic L a m i n o acid decarboxylase. However, only t h e L enantiomers in these d l mixtures are decarboxylated by t h e enzyme. E n z y m e inhibitory actions of 3, 6, a n d 7 were compared with those of dl-a-methyldopa' a n d caffeic acid (3,4-dihydroxycinnamic)8 ( T a b l e I ) , Caffeic acid a n d dl-a -methyldopa inhibited t h e conversion of L-Dopa to dopamine in all concentrations studied and M). T h e reaction was completely (10 - 2 : blocked by 10- M concentrations of these compounds. Inhibition with either compound was observed when it was a d d e d to t h e enzyme preparation simultaneously with t h e [>-Dopasubstrate a n d when i t was a d d e d t o t h e preincubation mixtures. In contrast, 3, 6, a n d 7 were effective inhibitors only when t h e y were preincubated with t h e enzyme a n d pyridoxal 5-phosphate. Compounds 6 a n d 7 completely inhibited the reaction M , while a concentration of a t concentrations of M of 3 was required for complete inhibition. Results obtained with control enzyme incubations containing t h e various inhibitors a n d equivalent a m o u n t s of KOH d e m onstrated t h a t t h e observed inhibitions were functions of concentrations of 3, 6, or 7 a n d not of possible changes in t h e p H of t h e m e d i u m . Rates of Dopa decarboxylase mediated reactions are d e p e n d e n t u p o n pyridoxal 5-phosp h a t e concentration^.^.^^ Christenson, et al., established t h a t concentrations of pyridoxal 5-phosphate higher or lower t h a n t h e o p t i m u m M) resulted in a decrease in t h e rate of the enzyme reaction. T h e possibility was considered t h a t t h e rigid a - m e t h y l d o p a analogs produced their observed inhibitory effect by removal of pyridoxal 5-phosphate from participation i n t h e reaction cia Schiff
*
base formation. Accordingly, controlled experiments were conducted in which a n additional 0.215 pmol of pyridoxal S-phosphate was added, either to s t a n d a r d preincubation mixtures containing inhibitor or to t h e preincubated enzyme with L-Dopa substrate. Results with these controlled experiments were identical with those obtained previouslJwith t h e tr-methyldopa analogs. which seem t o eliminate the possibility of t h e observed inhibitory effects involving simple inactivation of pyridoxal. However. the exact niiture of the inhibition of Dopa decarboxylase caused by 3, 6, a n d 7 remains to be determined by more sophisticated enzyme kinetic studies. Discussion On the basis of the d a t a on Dopa decarboxylase inhibition, it is concluded t h a t the pattern of ring oxygenation in 6 a n d 7 is conducive t o enzyme inhibitory activity. as compared t o 2 a n d 3. It is therefore appealing to speculate t h a t , a s has been p r o p ~ s e d ~for .~~ dopamine, apomorphine, a n d for the biologically active dihydroxylated 2aminotetralins, there is a common stereochemical a r rangement--a single favored conformation-for ty-methyldopa-like inhibitors of Dopa decarboxylase. T h e conformer of a - m e t h y l d o p a which seems likely to be involved in enzyme inhibition is 10 rather t h a n its rotamer 11.
HO
10
11
T h u s , it appears t h a t maximal dopaminergic agonist effects a n d maximal Dopa decarboxylase antagonist effect require t h e s a m e steric disposition of t h e 3,4-OH groups with respect to t h e side chain a t t h e 1 position on the ring. T h i s may reasonably suggest a great stereochemical similarity between dopaminergic receptors a n d t h e active catalytic site of L -amino acid decarboxylase. Experimental Section Melting points were determined in open glass capillaries using a Thomas-Hoover Uni-Melt apparatus and are uncorrected. .411 boiling points are uncorrected. Ir spectra were determined with Beckman IR5-A and IR-10 spectrophotometers. S m r spectra were recorded with a Varian Associates T-60 spectrometer (MelSi). Elemental analyses were performed by Galbraith Laboratories. Knoxville, Tenn.. and by the Microanalytical Service, College 01' Pharmacy, I'niversitl- of Iowa. Rhere analyses are indicated by symbols of the elements. the analytical results were within f0.4% of the theoretical values. l,j-Dimethoxy-2-amino-l-indanolHydrochloride (12). -4.2Dimethoxy-2-amino-1-indanone hydrochloride3 (5.0 g, 0.002 mol) in 500 mi of 9570 EtOH was hydrogenated for 3 days in a Parr shaker at room temperature with 2.1 g of 10% palladium on charcoal at a maximum pressure of 40 psig. The solution was filtered and evaporated under reduced pressure to give a white powder which was recrystallized from EtOH-Et,O to give 3.8 g (76%) of' product. mp 162-164". Anal. (CllH1&1N03) C, H, N . 1,5-Dimethoxy-2-indanone(13). A variation of a method of Thrift', was employed. A solution of 10.0 g (0.052 mol) of 12 in 400 ml of concentrated HCI was extracted with 1 I. of CsHs for 2 1 hr in a liquid-liquid extractor. The CeHs layer was evaporated under reduced pressure and the residue was recrystallized from petroleum ether (bp 30-68") to give 4.5 g (60%) of 13: mp 89-90"; ir (KBr) 1740 cm- (-0). Anai. (CllH1203) C, H. Spiro(4,5-dimethoxyindan)-2,5'-hydantoin(14). Compound 13 ( 3 . 5 g, 0.019 mol), 3.1 g (0.062 mol) of NaCN, 16.0 g of ammonium carbonate, and 80 ml of EtOH-H20 (3:Z) were heated at 55-60" for 6 hr. The mixture were then refluxed for 1.5 hr, and the volume was reduced to 40 ml and neutralized with concentrated HCI. On cooling, a solid separated which was recrystallized from EtOAc to give 3.5 g (73%) of 14: mp 189-190"; ir (KBr) 3300-3200
Journal of Medicinal Chemistry, 1974, Vol. 17, No. 5 567
Notes
white solid, mp 235-240" dec. Anal. (CllH14BrN04) C, H, N. (NH), 1770-1690 cm-I ((2-0). Anal. (C13H~N204)C, H, N. 1,2,3,4-Tetrahydro-5,6-dimethoxy-2(lH)-naphthalenone 0dl-2-Amino-4,5-dimethoxyindan-2-carboxylic Acid (15). Methyl Oxime (21). Compound 18 (6.64 g, 0.0322 mol) was meltCompound 14 (1.0 g, 0.004 mol) and 4.0 g of Ba(0H)z in 60 ml of ed over a steam bath, then 5.33 g (0.0644 mol) of methoxgamine HzO and 5 ml of EtOH were heated in a bomb a t 160" for 3 hr. hydrochloride was added, followed by 2.57 g (0.0644 mol) of The cooled solution was filtered and the filtrate was treated with NaOH in 32.2 ml of HzO. The resulting mixture was shaken over excess ammonium carbonate and then was filtered. Evaporation a steam bath for 0.25 hr, then was shaken in a closed container on of this filtrate gave a solid which recrystallized from EtOH-Hz0 a mechanical shaker and was gently heated with an infrared to give 0.67 g (75%) of white needles: mp 275-277"; ir (KBr) lamp for 0.5 hr, and then was shaken a t room temperature for a 1500-1620 cm-I (COO-); nmr (D20-AcOD) 6 2.80-3.81 (m, 4 H, total of 24 hr. The reaction mixture was extracted several times -CH2-), 3.82 (s, 6 H , -OCH3), 7.0 (s, 2 H, arom H). Anal. with EtzO, the combined extracts were dried (MgS04) and fil(ClZH15N04) C, H, N. tered, and Et20 was removed from the filtrate to leave an oil dl-2-Amino-4,5-dihydroxyindan-2-carboxylicAcid Hydrowhich was distilled, bp 165-169" (0.05 mm), to afford 4.0 g (52%) bromide (6).Compound 15 10.5 g, 0.0017 mol) in 8 ml of 48% HBr C, H, N. of product. Anal. (C13Hl~N03) was heated under N2 a t 150-160" for 1.5 hr. Evaporation of the 2-Amino-5,6-dimethoxy-1,2,3,4-tetrahydronaphthalene Hydark violet solution under reduced pressure (steam bath) left a drochloride (22). The method of Feuer and Braunstein14 was embrown residue which was recrystallized twice from 2-PrOH-Et20 ployed. To a cooled (0")mixture of 3.8 g (0.0161 mol) of 21 and 20 to afford 0.360 g (60%) of a white solid, mp 262" dec. On exposure N OH, ~ ) ml of tetrahydrofuran was slowly added with stirring 12.4 ml to air, this material turned brown. Anal. ( C I ~ H ~ Z B ~ C, (0.0124 mol) of 1 M diborane in tetrahydrofuran (Aldrich ChemiN. cal Co.) under XZ.The resulting mixture was stirred a t 0" for 1 hr 1,2,3,4-Tetrahydro-5,6-dimethoxy-l-naphthalenol (16). 3,4and then was refluxed for 2 hr. The reaction mixture was again Dihydr0-5,6-dimethoxy-l(2H)-naphthalenone~~ (20.0 g, 0.097 mol) cooled to 0" and 10 ml of H20 was added, followed by 10 ml of in 500 ml of 95% EtOH was stirred with 1.5 g (0.032 mol) of 20% KOH. This mixture was refluxed under Nz for 1 hr and then NaBH4 for 6 hr, then 0.75 g (0.016 mol) of additional NaBH4 was was permitted to stand overnight under Nz. It was then transadded, and stirring was continued for a total of 10 hr. HzO (100 ferred to a separatory funnel and was extracted three times with ml) was added, the volatiles were removed under reduced presEt20 in a Nz atmosphere. The combined Et20 extracts were sure, and the residue was extracted several times with C&. The dried (Na2S04) and filtered, and the filtrate was treated with excombined extracts were washed with HzO, 10% HC1, and finally cess ethereal HC1. The resulting white solid was washed several with H20 and were dried (MgS04). CsH6 was removed under retimes with anhydrous Et20 and then with hexane and was reduced pressure and the resulting oil was distilled a t 135-140" crystallized from MeOH-Et20 to afford 1.35 g (35%) of crystals, (0.025 mm) to give 17 g (85%) of a clear liquid. Anal. (C12Hl603) mp 272-274" (lit.5m p 270-272"). C, H. Enzyme Studies. Materials. Aromatic L -amino acid decarbox5,6-Dimethoxy-3,4-dihydronaphthalene(17). Compound 16 ylase from hog kidney cortex was obtained from Worthington Co. (20.0 g, 0.096 mol) was heated for 5 min in the presence of a crys(Lot No. E-EPJA, 47 units of activity/mg of protein). One unit of tal of KHS04 and then the viscous oil was distilled at 95-99" (0.025 mm) to afford 16.6 g (9070) of product: nmr (CDC13) 6 activity is defined as the amount of enzyme which converts 1 2.05-3.00 (m, 4 H, -CHz-), 3.80, 3.84 (s, 6 H, -OCH3), 5.75-6.55 nmol of L-Dopa to dopamine per minute under prescribed assay (m, 2 H, -CH=CH-), 6.75 (s, 2 H, arom H). Anal. (C12H1402) C, c0nditions.l The enzyme was stable a t -20" for several months. Sources of the following chemicals are as indicated: dl-a-methylH. 1,2,3,4-Tetrahydro-5,6-dimethoxy-2(lH)-naphthalenone (18). dopa, L-Dopa, and pyridoxal 5-phosphate (Sigma); dopamine (AlTo a chilled, stirred solution of 17.5 g (0.090 mol) of 17 in 125 ml drich). Deionized HzO for buffers was redistilled from all-glass of CHC13 was added over 0.5 hr a suspension of 25 g (0.145 mol) apparatus. of m-chloroperbenzoic acid in 175 ml of CHCl3. The resulting Enzyme Incubation Procedure. The procedure was essentially mixture was stirred in the cold for an additional 2 hr. It was then that described by Christenson, et al. Incubations were conducted filtered and the filtrate was extracted several times with cold 10% in 7-dram snap-cap vials which were agitated in the air at 37" in a New Brunswick G-76 water bath-shaker. The standard enzyme NaOH and finally with HzO. The CHC13 was removed under reduced pressure (steam bath) to give an oil which was dissolved in incubation mixture consisted of 0.1 ml (5 mg of protein) of the 150 ml of EtOH and 100 ml of 2 N HC1. This solution was heated enzyme preparation which was preincubated for 15 min with 2.4 ml of a 0.1 M potassium-sodium phosphate buffer (pH 6.8), confor 1 hr on a steam bath. The deep red solution was cooled and extracted with C6H6; volatiles were removed from this extract taining 0.21 wmol of pyridoxal phosphate. After preincubation, 0.5 under reduced pressure to leave a dark red oil which was shaken ml of phosphate buffer containing 8.95 wmol of L-Dopa was added, vigorously with a solution of 75 g (0.40 mol) of NaHS03 in 150 ml and the incubations were continued with shaking for 10-30 min. of HzO and 50 ml of EtOH. The voluminous bisulfite addition Enzyme reactions were terminated by quick-freezing in an aceproduct which separated was collected on a filter and was washed tone-Dry Ice bath, and the frozen samples were lyophilized and with EtOH and then with Et2O. It was dissolved in a solution of prepared for thin-layer chromatography. 172 g (0.60 mol) of Na2C03 in 500 ml of HzO. The ketonic prodInhibition studies with rigid a-methyldopa analogs and with uct was extracted with C&; the extract was washed with 10% dl-a-methyldopa and caffeic acid were performed in two ways: by HC1 and then with HzO and was dried (MgSOJ, and volatiles adding the inhibitor candidate and L-Dopa simultaneously to the were removed under reduced pressure. The residue was crystalpreincubated enzyme; or by incubating the enzyme preparation lized from cyclohexene to give 13.5 g (71%) of white needles: mp with the inhibitor candidate for 15 min prior to addition of the L 64-65"; ir (KBr) 1700 cm-l ( C - 0 ) ;nmr (CDC13) 6 2.45, 3.15 (t, 4 Dopa substrate. Complete reaction mixtures were then incubated H, -CHz-), 3.45 (s, 2 H, -CHz-), 3.80, 3.84 (s, 6 H. -OCH3), 6.85 as previously described. The results of all enzyme incubations (s, 2 H, arom H ) . Anal. (C12H1403) C, H. were compared with those obtained with the standard incubation S p i r o (5,6-dime t h o x y 1,2,3,4- tetrahydronaphthalene)-2,5'mixture containing L-Dopa. hydantoin (19). The procedure was that used for 14, using 1.5 g Tlc Analysis of Enzyme Reactions. Samples of enzyme reac(0.0073 mol) of 18, 1.6 g (0.03 mol) of NaCN, 8.0 g of ammonium tion mixtures were examined semiquantitatively by tlc. Lyophicarbonate, and 80 ml of EtOH-H20 (3:2). The product was relized samples were suspended in 1.0 ml of anhydrous EtOH and ) silica gel GF234 tlc plates crystallized from EtOAc (charcoal) to afford 1.40 g (72%) of a these solutions were spotted (60 ~ 1 on pyridine-AcOH-I-butanol-HzO and were developed in white solid, m p 235-236". Anal. (C14HleN204) C, H, N. (8:12:60:20).15 In this system, the Rf values of L-Dopa and dopdl-Z-Amino-5,6-dimethoxy1,2,3,4-tetrahydronaphthalene-2carboxylic Acid (20). The procedure was the same as for 15, using amine were 0.25 and 0.51, respectively. 3, 6, and 7 and their respective amine decarboxylation products also separated well in 1.0 g (0.0036 mol) of 19, a reaction time of 5 hr, and reaction temperature of 160". The product was recrystallized from this system. Developed tlc plates were visualized by quenching of EtOH-HZO to afford 0.65 g (72%) of white needles: m p 292-295" 254-nm-induced fluorescence and by spraying with freshly predec; ir (KBr) 1500-1620 cm-1 (COO-); nmr (D20-AcOD) 6 2.20pared 1% FeC13 in H20-MeOH (1:l). The lower limit of detection 3.30 (m, 6 H, -CHz-), 3.80, 3.84 (s, 6 H, -OCH3), 6.90 (s, 2 H, of dopamine with the FeC13 reagent was approximately 1 Fg, arom H ) . Anal. (C13H17N04) C, H, N. which would represent the equivalent of a 2% enzymatic converdl-2-Amino-5,6-dihydroxy-l,Z,3,4-tetrahydronaphthalene-2- sion of L-Dopa to dopamine in the standard incubation system. carboxylic Acid Hydrobromide (7). The procedure was that emEstimation of the amount of dopamine formed in enzyme reaction ployed for 6, using 0.500 g (0.0049 mol) of 20, a reaction time of 3 mixtures was based on colorimetric evaluation of the blue-black hr, and reaction temperature of 150-160". The product was recolor produced with FeC13 reagent relative to standard amounts crystallized twice from EtOH-Et20 to afford 0.45 g (75%) of a of reference compounds.
-
,568 JuurnalofMedicinal Chemz5tn 1974 Vol 17. Yo i
Acknowledgment. This work was supported by Grant NS-04349, National Institute of Neurological Diseases and Stroke. References ( 1 ) J . R . Taylor, J. W. Lewis, and M. Jacklin, J. Med. Chem.,
14. 1226 (1970). (2) S. N . Rastogi. J. S . Bindra, and N.Anand, Indian J. (‘hem.. 9, 1175 (1971). (3) J . G . Cannon, J . C. Kim. M. A. Aleem, and J. P. Long, J. Med. C‘hem.. 15, 348 (1972). ( 4 ) J. P. Long, S. Heintz, J. G. Cannon, and J. C. Kim, ASPET Fall Meeting, East Lansing, Mich., 1973, Abstract No. 129. (5) W. K. Sprenger, J. G. Cannon, B. K. Barman. and A. M. Rurkman, J Med. Chem., 12,219 (1969).
(6) W. Lovenberg, H. Weissbach. and S. Udenfriend. J
hi()/ Chem., 237,89 (1962). ( 7 ) T. L. Sourkes, Arch. Riochem. B i o p h j ’ ~, 51,444 (1954). (8) W. J . Hartman, R. I. Akawie, and W. G. Clark. .J. N i o i Chem., 216,507 (1955). (9)
