HYPOGLYCEMIC 3,vj-DISUBSTITUTED
,January, 1964
97
HYD.4NTOINS
Preparation and Hypoglycemic Activity of Some 3,5-Disubstituted Hydantoins JOSEPH G. LOMBARDISO ASD CLIFFORD F. GERBER Medical Research Laboratories, Chas. Pjker K: Co., Inc., Groton, Connecticut Received .4ugiist 1 , 1963 Home new 3,5-disubstituted hydantoins were prepared for testing as hypoglycemic agents. I n addition, some 1)-5-[4(or 5)imidazolylmethyll hydantoins and 1,-5-[4(or 5)imidazolylmethyll thiohydantoins, prepared by reaction of L-histidine methyl ester with various isocyanates, are described and their physical and pharmacological properties discussed. An explanation is offered for the observed increased acidity of these imidazoles over that of other alkylimidazoles. Four new isocyanates were prepared and characterized in the course of this work. Although a modest level of hypoglycemic activity was observed in the rat by the oral route, no activity was found on administration t o guinea pigs or dogs.
Certain 5,5-disubstituted1 and 3-substituted hyd a n t o i n ~ are ~ reported to possess a variety of pharmacological activities. Of special interest was the reported3 hypoglycemic activity found for simple 3substituted hydantoins. This report prompted the preparation of further simple derivatives of 3,S-disubstituted hydantoins as well as a series of S-substituted-3- [4( or 5)-imidazolylmethyl]hydantoins. R i p 0
HNKNRz 0 Synthetic procedures differed in those cases where R1 alkyl or aralkyl from those where R1 = 4(or 5)imidazolylmethyl and will therefore be discussed separat ely . (A) 3-Alkyl 5-Substituted Hydantoins.-Reaction of an a-isocyanato ester with an amine to give a hydantoate ester (11) which is then cyclized in acid, offered the simplest, most flexible of the many reported routes4 to hydantoins. A previously known5 technique for preparing the required a-isocyanato esters from a-amino esters and phosgene served very well. I n two cases optically pure amino esters (L-phenylalanine ethyl ester and L-leucine ethyl ester) were employed as starting materials, while in another series an optically inactive ester was used (DL-alanine ethyl ester) (Table VI, Experimental section). a-Isocyanato esters reacted with amines in ether solution in most cases in near quantitative yields to give analytically pure hydantoate esters (11) (see Table I). =
RzSHz
+ RICHCOOCzHs I
+
RiCHCOOCzHs I
~HCOSHR~ I1
SCO
Hydantoins (I) were prepared by cyclization of the hydantoates I1 in aqueous acid a t steam bath temperatures. R RICHCOOCzHj
I
NHCONHRz
I1
HL A
i
p
0
HNYNRz + C2H50H 0 I
(1) A. Frost, J . Mental Sci., 86, 976 (1939). (2) E. S.Sehipper and A. R. Day, "Heterocyclic Compounds," Vol. 5, R. C. Elderfield. Ed.. John Wiley a n d Sons, Inc., New York, N. Y., 1957. p. 262. (3) A. Roy, S. Zaidi, a n d S. Popli, J . Srz. I d . Res. (India), 19 (31, 75 ( 1960). (4) See ref. 2 , p. 256. ( 5 ) S. Goldsrhmidt and hl. Wick, Ann., 6'76, 217 (1932).
Yields were usually near quantitative and first crops analytically pure. Table I1 summarizes the data on these 3-substituted 5-alkylhydantoins. Some compounds of type I were optically active (footnotes to Table 11) suggesting that the series of reactions from optically active amino ester to the hydantoins I probably had little effect on the asymmetric carbon atom. (B) L-5-[4(or 5)Imidazolylmethyl] 3-Substituted Hydantoin Hydrochlorides (IV) .-Preparation of L-5[4(or 5)imidaxolylmethyl] 3-substit uted hydantoins by the general procedure described before was thought to be impractical, since the required a-isocyanato ester from histidine ethyl ester mould not be expected to be stable. Instead, reaction of a series of isocyanates with L-histidine methyl ester was employed. /;T CHzYHCOOCH3
NvNH N H 2 + R 2 N C 0 -+
,,,=q CH2yHCOOCH3 H+ NH NHCONHRz N
I11
HN
'd
HN
N .HC1
IV
NRz
K 0
For this sequence, L-histidine methyl ester was prepared from its hydrochloride a t low temperature and stored in the freezer for use without further purification. Reactions of this amino ester with a series of isocyanates in chloroform solution gave methyl L-2[4(or 5)imidazolylmethyl] 5-substituted hydantoates (111) in good yields (Table 111). Four new isocyanates (p-trifluoromethylphenyl, hexadecyl, 2,4-dimethoxyphenyl, and n-octyl) prepared and characterized in the course of this work are described in the Experimental section. I n one experiment designed to prepare methyl L- 2- [4(or 5)-imidazolylmethyl]-5- (p-met hoxypheny1)hydantoate (111, Rz = p-CH30CsH4),spontaneous cyclization to L-3-(p-methoxyphenyl)-5-[4(or 5)-imidazolylmethyl ]-hydantoin occurred during attempted recrystallization of the hydantoate from boiling ethanolwater (see Experimental). Apparently, activation (k, increased nucleophilicity) of the 5-nitrogen atom by the p-methoxyphenyl substituent was sufficient to cause cyclization in the absence of acid. Cyclization of hydantoates (111) by heating in 6 N hydrochloric acid yielded the desired hydantoin hydro-
98
JOSEPH G. LOMBARDINO A N D CLIFFORD F. GERBER
VOl. 7
TABLEI ETHYL2,5-DISUBSTITUTED HYDANTOATES RiCHCOOCzHs
I
I1
NHCONHRz Yield,
Empirical formula
%
M.p., OC.
81 86 89 100 91 93 98 90 88 94 95
134-135 80. 5-81.5 125-126.5 38.5-40.5 93-95 77-79 85-87 144.5-145.5 111-113 120-120.5 96-98
CizHi~ClN~03 CizHisNzOa Ci3HisNz03 Ci4HzsNzOs CisHziClNzO3 Ci7H26NzOs Ci6HzdN~O8 Ci8Hi~ClN203 CzoHZ4Nz06 Ci7H2zNz03 C16H24N203
-Carbon, %Calcd. Found
53.24 61.00 62.38 61.73 57.59 60.33 65.72 62.33 64.50 69.91 65.72
53.18 61.13 62.40 62.09 57.67 60.12 65.71 62.63 64.36 69.79 65.99
-Hydrogen, %Calcd. Found
-Nitrogen, %Calcd. Found
5.56 5.65 6.83 6.82 7.25 7.27 10.37 10.25 6 . 7 7 6.68 7.75 7.58 8 . 2 7 7.97 5 52 5 . 5 2 6.50 6.49 6.80 6.78 8.27 8 . 3 9
10.35 11.86 11.50 10.65 8.96 8.58 9.58 8.08 7.52 8.58 9.58
Hydrogen, % Calcd. Found
Nitrogen, yo Calcd. Found
10.32 11.88 11.28 10.75 8.62 8.67 10.00 8.08 7.47 8.56 9.98
TABLE I1 3,5-DISUBSTITUTED HYDANTOINS
R i . v O
HNKNR2 0 I Carbo n, % Calcd. Found
Yield,
%
M.p., OC.
96 169.5-170.5 76 170.5-171.5 86 165.5-166.5 96 72.5-73.5 97 189-1 9 1 97 178.5-181.5 137.5-138.5 98 80 66.5-67.5 175.5-179.5 99 89 144.5-145.5 119-121 99 137.5-139.5 99 a Used m-alanine ethyl ester hydrochloride as starting material for this series. ( c 1.0, ethanol).
chlorides (IV) in good to excellent yields (Table IV). Infrared spectra of all hydantoins of type IV exhibited strong carbonyl absorption at or near 5.65 and 5.85 p, supportings the cyclized structure IV. Four attempted cyclizations of imidazolylmethyl hydantoates failed to give isolable products. These included 111: RZ = 2-chlorophenyl; Rz = 2,5-dichlorophenyl; RZ = 2,4-dimethoxyphenyl; and Rz = carbethoxymethyl. In the first two cases, steric hindrance of the 5-nitrogen atom by the 2-chloro atom probably prevents cyclization; starting material could always be detected (papergram) in the complex mixtures. Where Rz = 2,4-dimethoxyphenyl, again the 2-substituent was probably responsible for incomplete cyclization. After 3 hr. reflux in 6 N hydrochloric acid, infrared spectra suggested the presence of the desired hydantoin but this could not be separated from impurities. I n the last case, where RZ = carbethoxymethyl, two cyclization paths are possible for the hydantoate since two ester functions are available for reaction with either the (a) N-5 or (b) N-3 atom. Indeed, papergrams indicated the presence of two compounds, neither of which was starting material; how(6) L. J. Bellamy, "The Infrared Spectra of Complex Molecules," 2nd, Ed.. John Wiley and Sons, Inc.. New York, N . Y., 1958. p. 221.
53.60 63.15 64.50 63.57 58.61 61.89 68.51 67.05 63.66 65.89 72.60 68.66 [ ( Y ] ~ ~-44.1' D
53.46 63.14 64.69 63.68 58.53 61.63 68.27 67.12 63.90 66.24 72.83 68.27
4.04 3.99 5.35 5.19 5.92 6.00 9.80 9 . 4 3 5.67 5.70 6.90 6 . 9 5 7.37 7.29 10.51 10.47 4.36 4.41 5 . 5 6 5.41 5.75 5 . 6 8 7.37 7.40 ( c 1.0, ethanol).
12.47 14.73 13.72 12.39 10.51 9.59 11.38 10.44 9.32 8.59 10.00 11.37
12.42 15.00 14.08 12.78 10.63 9.79 11.45 10.68 9.31 8.65 10.13 11.43 [CY]~'D-64.3"
ever, no further attempts were made to separate and characterize the mixture. In three cases where optical rotation was determined, the ~-5-[4(or 5)imidazolylmethyl]hydantoins were levorotatory [IV: RZ = p-ClC&, [ L ~ ] D *-55.8' ~ (c 0.7, ethanol); Rz = CH3CHZCH2, [ ( Y ] D ~-44.0' ~ (c 1.0, ethanol); Rz = C6H5, [ C Y ] D ~-89.1' ~ (c 1.0, ethanol)] suggesting that the series of reactions from L-histidine methyl ester to IV probably had little effect on the asymmetric carbon atom. Titrations with sodium hydroxide in 1:1 dioxanewater of two compounds of type IV revealed an increased acidity for these compounds (IV: Rz = CH3(CHZ)3, pKa = 5.1, and RZ = p-ClC&, pKa = 5.0) over simple alkylimidazole hydrochlorides [e.g., (4 or 5)-methylimidazole hydrochloride has pKa 7.51. One possible explanation for this enhanced acidity may be the favorable steric arrangement of the free base of IV (IVa) which allows strong hydrogen bonding between the imidazole and hydantoin rings.
99
HYPOGLYCEMIC 3,s-DISUBSTITUTED HYDANTOIKS
January, 19G4
TABLEI11 L-hfETHYL 2-[4(Or 5)IMIDAZOLYLMETHYL] 5-SUBSTITUTED HYDAKTOATEB CHzyHC02CHz HN-N
NHCONHRz
I11 Yield,
Recrystn. solvent
7c
hI.p., o c .
54 90 95 99 85 83 3 91 87 49 81 87 73 83
161.5-162.5 156.5-157.5 151.5-152.5 138.5-139.5 144.5-146.5 167.5-169.5 152.5-153.5 166.5-166.5 191-193 120-122 164.5-166.5 116-119 83-87 155.5-157.5
CHC13 CHCla-EtpO
C1pHmK403 53.71 Ci4Hi,ClS,03 52.10 CIIHBN,O~ 51.96 Ci4H1sN403 58.32 CibHi8N403 59.59 C I ~ H ~ , C ~ J X &47.07 ~ C14H~5ClS,0, 52.10 C I ~ H I S B ~ S ~45.79 O~ C1&2?;403 57.12 C I ~ H ~ K ~ O59.23 ~ C I ~ H ~ O S ~ O ,55.17 Cp4H44N403 66.02 C12H18N405 48,32 C15Hi5F3S403 50.56
EtOH EtOH CHC13-hexsne CHC13-hexane EtOH-hexane EtnO-EtOH EtOH-hexane EtOH LIenCO-Et?O EtOH-H20
-Hydrogen, 70Calcd. Found
-Carbon, %Calcd. Found
Empirical formula
53.56 52.31 52.00 58.38 59.58 46,98 52.07 45.81 56.82 59.36 55.19 66.17 48.55 50,82
7.51 7.25 4.68 5 . 0 2 7.13 7.16 5.59 5.38 6.00 6.26 3.95 3.86 4 , 68 4 . 6 8 4.12 4 . 1 0 7.54 7.34 8.70 8 . 6 4 5 . 7 7 6.02 10.16 10.31 6.08 6.23 4.24 4 . 0 0
-Nitrogen, 70Calcd. Found
20.88 17.36 22.08 19.43 18.53 15.69 17.36 15.26 19.04 17.27 16.09
20.79 16.99 22.26 19.41 18.86 15.44 17.30 15.47 19.09 17.66 16.22
18.78 19.10 35.73 15.81
TABLE IV 5 ) I ~ ~ \ l r D A Z o I , Y L ~ ~ E T H3-SUBSTITUTED YL]
L-z-[4(Or
HN
N
Y HCl Rrcrystn. solvent
Yield,
56
A1 p., OC.
96 93 84
221-222 285-288 2 14-2 17 262 5-264 5 277 5-278 5 292-294 271 5-273 269 t5-271 5 236-238 221-226 287-289
84 74 80 87 TO 84 90 52
t5
EtOH-Et& EtOH-EtpO EtOH-EtrO EtOH-Et& EtOH-Et& EtOH EtOH-Et20 EtOH EtOH EtOH EtOH
The stabilized, hydrogen-bonded form IT’a displaces the equilibrium to the right thus increasing the apparent acidity of IV over that to be expected of an alkylimidazole hydrochloride. (C) ~-5-[4(or5)Imidazolylmethyl] 3-Substituted-2thiohydantoins (V).-By a procedure similar to that used in preparing IV, L-histidine methyl ester was treated with thioisocyanates in an attempt to prepare thiohydantoates (and thence thiohydantoins by acid cyclization). Ho~vever,only spontaneous cyclization to the thiohydantoins (V) was observed. Activation of the 5-nitrogen in the thiohydantoate by the neighboring sulfur atom evidently facilitates this cyclization. ,rq- CHzYHCOOCH3
HNvN
NHz
+ RNCS J
v
s
HN
K n
HYDAXTOIS HYDROCHLORIDES
NR2
%--
--Carbon. Calcd.
Found
48.44 47.72 46.72 53.34 54.81 42.01 52.26 52.10 54.78 62.63 46.61
48.17 47.56 46.51 53.27 54.56 42.26 52.06 52.08 54.65 63.06 46.31
-Hydrogen, 70Calcd. Found
5 3 5 4 4 2 6 4 7 9 3
91 39 45 46 60 98 07 68 66 37 33
6 18 3 73 5 82 4 30 4 78 3 09 6 35 4 80 7 44 9 32 3 33
--Nitrogen. %Calcd. Found
20.54 17.13 21.66 19.14 18.27 15.08 18.75 17.36 17.04 12.70 15,53
20.55 17.13 21.35 19.33 18.47 15.37 18.96 17.31 17.01 12.58 15.34
Analytical data as well as infrared spectra (Table V) support the thiohydantoin structure V since strong absorptions corresponding to the 4-carbonyl are seen a t 5.7-5.8 p (reported6 5.6-5.8 p) and to the 2-thiocarbonyl of the thiourea-like portion of the ring at 8.28.8 p (reported67.2-8.9 p ) . Pharmacological Evaluation.-All of the hydantoins described above were administered orally to rats a t 100 mg./kg. and blood glucose levels measured a t 2 hr. intervals. Ten control rats were run concurrently with each compound. Blood glucose was determined by a microadaptation of the method of Hoffman’ using an Auto-Analyzer. Sone of the 3,s-disubstituted hydantoins listed in Table I1 decreased blood glucose levels to any significant degree in the rat. Certain 5- [4(or 5)-imidazolylmethyllhydantoins, however, showed modest hypoglycemic activity in the rat (Table VII). These blood sugar level reductions could be reproduced in successive experiments. Compound IV, R = 4-chlorophenyl, was also administered to guinea pigs (subcutaneously at 40 mg./kg. and orally a t 100 mg.,’kg.) and dogs (orally. (7) W. S. Hoffman, J . Bid. Chem., 120, 51 (1937).
100
I1
v
s
See T:~ble\ 11, Iootliotes ( I , b, initid vnliies I
1
\ rise in i)lootl sugw iron1
biiiiple 3-substituted hydantoiiis" arid that this inod-
crate lewl of a d \ - i t p exhihits a species specificity. Experimentalq Ethyl ol-Isocyanato Esters (Table VI).-At reflux, :I solution d 0.1 mole of appropriate amino ester h?-dr,lchloride in 100 rn1. dry toluene w a ~stirred vigorously, arid a rapid stremi of phosgene W:LS introduced over t)he solution for 2 hr. Reniovd of tlic toluene under reduced pressure yielded an oil which was v:wiiiiri1 distilled (Table \-I). All of these isocyanates :ire 1:ichrxni:rtors. Ethyl 2,5-Disubstituted Hydantoates (II).-In an erlenmeyer fiaslc equipped with it dropping funnel, magnetic stirring bar, and proterted by :t drying tube was dissolved 0.015 mole of an eth\.l anatii ester in 50 ml. of dry ether. To this solution W:LS added a solution of 0.015 mole of amine in 100 nil. ether. After stirring for 0.5 hr., the solvent vias evaporated to half voliiine and cooled. Filtration of the solid and drying under v:tci:uni usually gave itnalytically pure product (Table I). Infrared absorptions due to C=O functions in I1 are found at or near 5.71 and 6.05 p i n all cases.
2'; ing. kg.) hut 110 significant effect or1 blood sugar coiild lie observed. T'ahies f'oi,a cliriically useful hypoglycriiiic agent, chlor*propamide, are iiicluded for i.cfciwicc in Table TII.
l;iiially, Tablr T-III presents data oil some thiohydaiitoiiis prepared as part of this same synthetic prograin. .igain. a c.ompouiid sii(~1ias a \', I< = CH1j('€IJ6, was foiirid to be ciitirely inactive i i i the guinea pig dcspite denioiistrable inodest activity in tlw rat. 1'1-om thebe data it m n j lw seen that most derivatixm of tiydaritoiii studird i i i the preseiit iiivestigatioii offt.1. 110 ntlvaiitagr over the n-cak activity rcpoited foi.
3-Substituted-5-Alkyl Hydantoins (I). General Procedure.A solution (or in :i, very few cases, a suspension) of 0.015 niole of :In eth>-l 2,5-disubstituted hydantoate (11) in 15 nil. of 6 hxdrochloric acid was warmed 911 the steani bath for 1 hr. .\cat.tone was sometimes added where required t o so1ul)ilize the h>,dent,oate. If cooling to 0" did not precipitate the prIJdll('t, evaporation of all solvent followed by :tn ethanol-ether trituratiirli wm effective. .ilmost all products were obt:tined :nislytic~:illy pure from this procedure (Table 11). I n two cases opticall>-pure amino esters (r,-piienylelaiiiIie et h>.1 ester and L-leucine ethyl ester) were employed as startiiig niaterials, while in another series an optically inactive ester WLY usccl (UT,-alanineethyl ester) (Table TI, Experimental). tnfrared absorptions due to carbonyl functions in I :we ftrund :it or near 5.65 and 5.85 p i n all cases. L-Histidine Methyl Ester.-This iriaterial 1%-asprep:treti frorri 1,-histidine methyl ester dihydrochloride b>-the method of' Aremi-
January , 19G-I
HYPOGLYCEMIC 3 , 5 - D I S U B S T I T U T E D HYDANTOINS
field and W ~ o l l e y . ~The liquid product slowly crystallized in the cold (91y0 yield) and %'as used without purification in the next step. The solid appears to be unchanged after 3 months in the freezer. Methyl ~ - 2 - [ 4 ( o r5)-Imidazolylmethyl] 5-Substituted Hydantoates (III).-A solution of 0.02 mole of histldine methyl ester (free base) in 25 ml. of chloroform (predried over calcium chloride) wab prepared at 0" in a flask protected by a drying tube. From a dropping funnel was slowly introduced 0.02 mole of an isocyanate. After stirring at room temperature for 0.5 hr. a solid usually precipitated. I n the absence of a precipitate, evaporation of solvent under vacuum left a solid residue. Filtration and recrystallization gave analytically pure material (Table 111). Attempted Synthesis of Methyl L-2-[4(or B)Imidazolylmethyl] 5-(p-methoxyphenyl) Hydantoate.-Reaction of p-methoxyphenylisocyanate with histidine methyl ester free base as described above yielded 3.9 g. of solid, m.p. 123-127". Several attempts to prepare an analytical sample of this material by recrystallizing from ethanol-15 ater gradually raised the m.p. to 213-214". This material analyzed not for the hydantoate but for L-5- [4(or 5)imidazolylmethyl]-34 pmethoxypheny1)hydantoin. Anal. Calcd. CI,HlrN403:C, 58.66; H , 4.93; K, 19.57. Found: C, 58.65; H,4.93; K,19.39. A hydrochloride salt was prepared in methanol aolution, m.p. 269.5-271.5' (Table IT). Isocyanates.-Nost of the required isocyanates are commercially available and were used as received. Those prepared for the first time are: (a) n-0ctylisocyanate.-Phosgene was rapidly passed over a solution of 19.49 g. (0.118 mole) of n-octylamine hydrochloride in 200 ml. of refluxing dry toluene. After 2 hr., removal of solvent followed by vacuum distillation >ielded a colorless liquid, 13.7 g.(75%), b.p. 100" (26mm.),nn2j1.4292. B derivative was prepared by combining some n-octyhsocyanate with an equimolar amount of p-chloroaniline in dry chloroform solution for 0.5 hr. to yield a white solid, 1-(p-chloropheny1)3-(n-octyl)urea ; m.p. 130-131" after recrystallization from hot chloroform. Anal. Calcd. for C1bH23ClX20: C, 63.70; H, 8.20; N, 9.91. Found: C. 63.39: H.8.23: K,9.87. (b) Hexadecy1isocyanate.-Phosgene was passed over a solution of 40 g. (0.144 mole) of hexadecylamine hydrochloride in 500 ml. of refluxing dry toluene for 8 hr. T-acuum distillation yielded a colorless oil, 30.9 g. (80YG),b.p. 180-153" (8 mm.), n~~~1.4479. Reaction of some hexadecylisocyanate with an equimolar amount of p-chloroaniline in dry chloroform solution for 0.5 hr. followed by cooling to 0" gave a white solid derivative, l-(pchlorophenyl)-2-hexadecylurea; m.p. 123-124" after recrystallization from hot chloroform. Anal. Calcd. for C&3&13?0: C, 69.94; H, 995; X, 7.35. Found: C,70.11; H, 10.01; S,7.40. ( c ) p-Trifluoromethy1phenylisocyanate.-A rapid stream of phosgene was passed into a mixture of 26.4 g. (0.134 mole) of p-aminobenzotrifluoride hydrochloride ( m p. 217-220") in 500 ml. of dry toluene for 3 hr. ilfter 1.5 hr. a!l of the solid was in solution. Distillation of the toluene yielded a gelatinous material which on vacuum distillation yeilded a colorless oil, 10.6 g. (427,), b.p. 53' ( 8 mm.), n ~ 1.4695. ~ o Some unreacted starting amine salt was recovered from the undistillable pot residue. Reaction of some p-trifluoromethylphenylisocyanate with an equimolar amount of p-chloroaniline in dry chloroform gave 1(p-chlorophenyl)-3-(p-trifluoromethylphenyl)urea, m.p. 257.5258.5'. Anal. Calcd. for C I J I I O C I F ~ X ~ O C.: 53.43; H, 3.20; N, 8.90. Found: C, 53.09: H,3.22; S , 8 . 9 5 (d) 2,4-Dimethoxyphenylisoryanate.-Preparation of this isocyanate required four steps from 2,4-dimethoxybenzoic acid
-
(9) R. B. hIerrifield and D. W. W o o l l ~ y J . A m . Cliem. Soc.. 78, 4646
(19SR).
101
(Eastman Organic). The latter acid (50 g. (0.27 mole)) was converted to its methyl ester using methanol (300 ml.) and concentrated hydrochloric arid ( 3 ml.) in refluxing chloroform (250 ml.). After 24 hr., all solvent n a b evaporated, the crude ester dissolved in chloroform, n ashed successively n ith water, 5y0 sodium bicarbonate, and water, and the chloroform solution dried over sodium sulfate. Evaporation of solvent gave a pale brown oil (39 g , ) which was immediately combined with 19 g. of 957, hydrazine and heated on the steam bath for 5 hr. Cooling produced a solid which was filtered and washed with some cold of 2,4-dimethoxybenzhydrazide, methanol yielding 29.3 g. (81 m.p. 110-113". Derivntization x a s accomplished hy refluxing some of the hydrazide in acetone solution followed by cooling to 0" yielding N~-(2,4-dimethoxybenzoyl)-N2-isopropylidenehydrazine, m.p. 188-190". Anal. Calcd. for C&ler\'203: C, 61.00; H, 6.82; S, 11.86. Found: C, 61 22; H, 6.73; K,11.71. Slow addition of a solution of 10.59 g. (0.15 mole) sodium nitrite in 60 ml. of water to a cold solution of 29 g. (0.148 mole) of 2,4dimethoxybenzhydrazide in 750 ml. of N hydrochloric acid gave an immediate white precipitate. Heavy solid formation forced the addition of another 250 ml. of Ai hydrochloric acid. After stirring for 0.5 hr., filtration and drying yielded a white solid, 2,4-dimethoxybenzoylazideY26.6 g. (87%), m.p. 70.5-71.5' dec. (gas evolution). An analytical sample could not be prepared from this unstable material. The crude 2,4-dimethoxybenzoylazide was dissolved in 150 ml. of dry benzene in a system protected from moisture. Gradually raising the temperature to reflux caused vigorous nitrogen evolution. After 0.5 hr. of reflux, solvent was distilled a t atmospheric presvure and the residue distilled under vacuum to give 2,4dimethoxyphenylisocyanate, a colorless liquid, 15.7 g. (71yo), b.p. 140" (11 nim.), which solidified in the cooled receiver (m.p. 30-31 O ). A derivative was prepared by reacting 2,4-dimethoxyphenylisocyanate with an equimolar amount of p-rhloroaniline in dry chloroform solution. Cooling t o 0" and filtering yielded a white solid, l-(p-chlorophenyl)-3-(2,4-dimethoxyphenyl)ureay m.p. 187-189". Anal. Calcd. for ClbH~~C1N203: C, 58.73; H, 4.93; S, 9.13. Found: C,58.49; H,4.85; S , 9.17. ~ - 5 - [ 4 ( o r5)Imidazolylmethyl] 3-Substituted Hydantoin Hydrochlorides (IV).-A solution of 12.59 g. (0.039 mole) of methyl ~-~-imidazolylmethyl-5-(p-chlorophen~-l)hydrantoate, 75 ml. of acetone, and 75 ml. of 6 N hydrochloric acid was heated on the steam bath for 1 hr. Addition of 75 ml. of water and cooling to 0" yielded, in two crops, a white solid, ~-5-imidazolylmethyl-3(p-chloropheny1)hydantoin hydrochloride, 10.5 g. (837,), m.p. 293-294". I n cases where addition of water did not precipitate solid, all solvent was evaporated under reduced pressure and the residual solid recrystallized (eee Table IV). L-5-[4(or 5)Imidazolylmethylj 3-Substituted 2-Thiohydantoins (V).-A general procedure for the preparation of V from commercially available isothiocyanates is illustrated. To a solution of 4.5 g. (0.027 mole) of L-histidine methyl ester (free base) in 50 ml. of chloroform a t 0" was slowly added a solution of 3.1 g (0.027 mole) of n-butylisothiocyanate in 20 ml. of chloroform. After stirring 0.5 hr. a t room temperature, evaporation of half of the solvent under reduced pressure yielded a white solid, ~-5-[4(or ~)-imidazol~-lmethyl]-3-(n-butyl)-2-thiohydantoin, 4.1 g. (61%), m.p. 203-2 05'. Table T- lists the physical properties of these thiohydantoins.
x)
Acknowledgment.-The authors wish to acknowledge helpful discussions with Dr. G. D. Laubach and Dr. W. A I , Nclamore. The technical assistance of Mr. Selson Treadway, Jr. in the preparation of all compounds and blood glucose determinations by Mr. Frederic Smith are gratefully acknowledged.
