5-a-Hydroxybenzyluracil (VI).-5-Zlenzoyluracil (Vi (0.075 g., 0.25 Inole) was added t o a solution IJf potassium borohydride (0.037 g.) in 2 ml. of water. The mixture was stirred vigorousljfor about 10 min. a t room tcniperitturr and then for :I fiirt1ir.r .i ruin. at, 1 0 0 O . On acidifying with 3 .Y hydrochloric :id:tiit1 cooling in ice t,here was obtained 0.03 p-. (40 It wits recrystallized from ethanol, 1n.p. 221-2 llHIoN203:(1, 60.54: H, 4.63: S , 12.h1. A M ; S , 12.7s. Ultraviiilrt ;il)wrptiun: A,, 235 111p (0.1 S HC'I). A,,,,,, 288 IIIH (0.1 N NaOH). ('iiiiipi)~indsS : i d SI Lvore synthesized in the sanic nianner. Paper Chromatography.-The pyrimidines reported here \vert& i,liriimatograpliedon Whatmnn So. 1 papor by the desccnding technique in the biitanol--water ( 8 6 : 14 v./v.) solvent! systern d 1Iarkharrl and Smith.'* Tlie c~iironiatograiii wis riin 13-20 lir. (18)
Ifor testing ah cholesterol-lo~Veriiigagents. The ronipouiidr n eie prepared by two gencial routes Tlie first of' thew (roiitc -1)followed closrly the mcthotl of synthesis developed hy Chaliners, et nl , I 5 for tlrc. preparation 01 tlipromir> It01
I&>
\
C H 3 0 b O H
- HO&('H&HCO2Et I
R
NO
I
K
SO
"Ac
L 1 ridirii ( I-
THYROMIMETICS. I
September, 1963
TABLEI Compd. no.
R
R'
hI.p., O C .
%
Recrystsl. solvent
yield
Formula
555
-___ Calcd., %---C H N
7 -
Found, %----
C
H
N
Substituted p-Nitrophenols
R+R NO2 73-75 84-85 88-89 121-123 115 155-15ie
CClr-pet. ether CC14-pet. ether Ligroin Aq. HOAc EtOH Toluene
58 67 84 87 72 e'
CgHgXO3 CgHilSO3 C10Hi3S03 ClZHeSO3 C18H13NO3 ClzHij?j03
* 61 53 6 71
7.18
65.14 6.83 6.33
61.88 6.74
7.12
65.47 6.71
6.26
Substituted p-Nitroanisoles
B.P., 134-135 ( 3 mm.) B.P. 147-148 (8 mm.) B.p. 120" (0.5 mm.) 92-93 152-154
......
74
CyHiiYO3
59.66 6.12
7.73
59.34 6.08
7.81
......
82
CioHi3X03
61.53 6 . 7 1
7.18
61.66 6.90
7.34
......
84
CiiHi;NO3
63.14 7.23
6 69
63.32 7.27
6.83
77 69
Ci3HiiN03 CisHisNOa
57.60 59.55 61.24 66.24 i3.19
18.8gfi 17.58h 16.44' 15.04h 11,37h
57.63 59.26 61.30 66.55 72.85
EtOH EtOH-CHC13
Substituted p-Aminoanisoles
R+R,Hc, NH2 VIIIa b c d e
C2H5 i-C3H7 i-C4Hs CsHs CsHj
H H H H C&
196-198 210-212 162-164 237-239 242-244
Sublimed twice EtOH-( CzH5)zO EtOH-( C2Hs)g0 EtOH-( C2Hj)zO CHC13-pet. ether
72 76 97 89 85
CsH14ClNO CioHi6C1NO C1lH18CISO C13Hi,ClNO C1yH&lSO
7.52 8.00 8.41 5.99 5.82
7.63 18.74' 7.94 17.71h 8 . 3 3 16.61h 6.24 14.70h 5.94 11.3jh
Substituted p-Methoxyphenols
RqR OH
55.74 4.16 8.05 i-CsHiOH 43 C16H14nT207G 55.49 4.08 8.09 126-130' 58 B.P. 137-139 (8 mm.) 56.64 4.41 7.81 EtOH Ci~H16h-20~'56.67 4.48 7 78 92-93* 44 B.p. 161-163 (16 mm.) 57.50 4.70 7.39 Skelly-L CI8Hl8S2O7'57.75 4.85 7.48 85-87' 26 b.p. 200-203 (8 mm.) 60.43 3.69 6.83 CzoHirNzO7' 60.92 3 . 5 8 7.10 CzHjOH 149-150' 82.56 5.74 45 CisHiaOz 82.58 5.84 Toluene 166-167 See ref. a See ref. 18b and E. C. S. Jones and J. Kenner, J . Chem. SOC.,1842 (1933). b Fileti, Gam. chim. itul., 16, 117 (1886). 18c. See ref. 18b. e J. F. Bartlett and C. E . Garland, J . Am. Chem. SOC.,55,2064 (1933), describe the preparation of a mononitro-ocyclohexylphenol. It was reported to be a red oil, b.p. 144-146". f During distillation most of the material decomposed, b.p. 205-210' (4 mm.). For the 3,5-dinitrobenzoate. hChlorine analyses.
5Jti
I10
Va h c
cl e
11
“C.
11’
soli e n t
1
H
1’79-181
CHIOH
CzHs H L-CIH, H t-CaHs H Cyclo- H
155-157 164--166 177-lib 167-168
Acetone THF-(C2€I,)zO I>MF-H2O CH3OH
16O-IGZ
DhfF-HzO
CHI
Cf“,
f
Z-C3H7
2-C3Hr
ldd
10 13 86 X6 b3
a3
?‘lie second route (route 13) \vas based oil a s y n t h c i s of‘ thyroxine developed by Hillniaii.’6 More recciitly li this approach has been extended b y other Io of the :i’-i-hutyl dtiri\xti\.(. (1111)this a c i d treatmeiit caused t h e . loss oi t l i ~ t-butyl group ab idciiced by tlic isolatioii of 3,5-(11iodotliyroiiinc~ Tlie itlentitj. of thc diiodotli~roiiiri~~ (11
SOL
NOz VI1
I
KtIAc
I Xa
K
I
I
557
THYROMIMETICS. I
Sept'ember, 1963
TABLE I11 SUBSTITUTED 3,5-DINITROTHYROXIKEDERIVATIVES
Cotupd. no.
1\I.p., ' C .
yield
Fortnula
Calcd., %-H
--Found,
H
C
1-
R--
55.56 5.36 5.30 8.84 CsHj H 1Itt-n~ 5.12 $50.7" ( ~ 0 . 5 ) ~55.63 H CjHj IIa-L 5.61 56.28 5.56 8.59 i-C3H; H IIb-DL 5.50 -42.3" ( ~ 0 . 8 ) 56.52 H i-CsH7 IIb-D 56.62 5.61 ( ~ 1 . 0 ) $41.6 GC3H7 H IIb-L 5.94 57.52 5.81 8.35 i-C.iH9 H IIc-L [cY]'~D $43.9 (Co.7) 4.92 8.03 59.55 59,65 4.81 69 C26H2jS309 H 175-177 CsHj IId-DL 63.77 4.99 4.88 7.01 75 C32Hzs~30g 64.10 CCHL 175-178 CeHs Ire-DL All rotations Lvere determined in chloroform. All compounds Jvere recrystallized from ethanol, except IIb-D ( a s . EtOH). 125-127 109-110 128-130 104-105 107-109 107-109
Q
--c
n /c
"
R
11.11,,
40 57 37 31 55 55
55,5S CszHz~K3Og [a] *'D CzzHjjS309 56.44 C23H2iSsOg [aIz60 Cz3HZiX3Og [aIz5D Cz3HjiS30g C ~ ~ H Z S S ~ 57.25 O~
Route wed
"C.
Recrystal. solvent
yield
129-131 114-116 119-121 119-120 129-131 141-113
Aq. CzHjOH CjHjOH iiq. CsHjOH Aq. C2HjOH CyHjOH C2HSOH
30 48 52 i3 72 45
A B A A A
1 2 - I 30 CIH,OH 182-184 .4q. ClHjOH 118-120 CzHjOH 143-144 (CzHo)20pet. ether 147-148 Aq. CJHjOK 11111-ur. 137-138 C>H,OH IIIi-DL -411 rotations were determined in chloroform.
36 44 34 45
A A B B
18 48
B
COtlllKi.
nu.
IIIa-DL IIIa-L IIIb-DL IIIb-D IIIb-1, IIIC-I,
K COHL CzHj i-CsHi i-C3Hi i-C3H7 i-CdHg
11 '
H H H H H H
IIId-DL IIIe-ur. IIIf-uL I I I g-DL
:ic
was confirmed by elenieiital analysis, paper chroniatography, and a comparison of its melting point with that of an authentic sample prepared in our laboratory. T o gain some further insight into the course of this reaction the corresponding 4'-deoxy compound (XIa) was prepared. I n this case hydrolysis with hydriodic and acetic acids occurred without dealkylation. This implies that the loss of the t-butyl group in the 4'hydroxy series in some way involves the 4'-hydroxy group. This reaction has not yet been investigated any further. Three othei 4'-deoxy conipounds (XIb, e, and d, where R is 2', 3', and 4'-phenyl, respectively) were also prepared in a manner completely analogous to that used in the preparation of XIa.
Experimental?2 Preparation of Substituted p-Nitrophenols (VI) (Table I).-A solution of the required ketone in alcohol was added to an aqueous solution of an equimolar amount of the sodium salt of nitro-
h
B
5--
--Calcd.,
c
Foriiiula
H
I
C2sH33IJOj 45.04 C24HzgIjSOj 43.33
8.00 7 .05
n
I
46 57 43 68 56 44
3 3 4 4 4 4
96 75 31 32 30 29
39.16 39 62 38 90 38 TO 38 98 38.25
41 65 53 18
3 3 3 4
66 78 82 47
36.95 32.74 40 48 36 46
4.80 36.61 45.29 4.91 36.65 4.39 38.15 43.65 4.38 3S.18
n1alondialdehyde.~3 A 1 J I excess of dilute sodium hydroude was added and the mixture was stirred a t room temperature for 24 hr. The alcohol was removed by heating the mixture on n steam bath and the aqueous solution was cooled and acidified with dilute hydrochloric acid. The products were either filtered and recrystallized directly or were extracted into ether. The ethereal solutions were washed with base to separate phenolic material from other nonacidic material. Acidification of the alkaline washes followed by recrystallization yielded VI. Preparation of Substituted p-Nitroanisoles (VII) (Table I).To a stirred suspension of powdered potassium hydroxide in ethanol (about 2% w./v.) was added an equimolar amount of VI. The mixture was heated t o reflux and an equimolar amount of methyl iodide was added slowly. Bfter heating for 2 hr. an additional amount of methyl iodide equal to one-half that originally added was introduced slowly into the reaction mixture and stirring and heating were continued overnight. The alcohol was removed and the residue was dissolved in a mixture of ether and water. The layers were separated and the ethereal layer was washed ronsecutively with water, looosodium bisulfite, water, 10% sodium hydroxide, and again with water. After drying over magnesium sulfate the ethereal solution was evaporated and the residue was either recrystallized or distilled. Preparation of Substituted p-Aminoanisoles (VIII) (Table I).The substituted p-nitroanisoles (VII) dissolved in ethanol mere ~
(22) A l l melting points were taken i n a Thomas-Hoover melting point apparatus and are corrected.
N
9.15 8.62 8.73 8.65 8.62 8.36
?-
-Found, C
3,95 39.83 41 CzzH2j12SOj 41 . 4 6 CzjHjjIzXOj [ a ] " ~ $52.2 (C 0.5)" 41 C23H2i12X05 42 42 4.18 38.97 42 Cj3HziIjXOj [ a ] " ~-42.4 ( C 0.7) 42 Cj3H2i12S05 [a] P ~ D $47 3 (e 1.0) 42 CjiH2JzXC)j 43.33 4.39 38,15 43 [a]"D $48.3 (C 1.1) C26H2&TC& 4 5 . 5 7 3.68 37.04 45 C3zHggIzSOj 50.48 3.84 33.34 50 C21H2s12SOj40.47 3.72 40.73 40 4 52 36.71 45 CyGHJ2SOj 45.1;
F
(23) P. E. F a n t a ,
O w .Syn., S a , 95 (1952).
rctliicwl in :I Parr :qp:ir;ttus in the preseiice ot" ICc,.{, P d / C ( 1 .O
x . /O. 1 inole of nitro coinpound) under nn initial pressure of :5--4 : t t i i i . of hydrogen. When the reduction had been cwnpleted, the cat:iIyst was removed, the solvent was evaporated, and the residue was taken up in benzene and evaporated. This last oper:ition was repeated 2-3 times with fresh portions of k~enzene t i 1 reiiiove traces of \niter. The residue was taken up in a sniall x-olriine of ether and saturated with dry h>-drogen chloride. The precipitated hydrochloride w:is filtered, mnshed with rthc,r. :ind recrystallized. Preparation of p-Methoxyphenols (I) (Table I'l.--T(i a stirrod
slurry of 10 11-11, of ~ ~ i t i c wrated it sulluric :wid :tiid ire w i s atltletl 0.2 nicile ( i f i.111. TI) tliis stirred. i *r i i i l e d iiiixtnre w i s :~ddetliri pirtiiiiis 15 R. of +o(liiini nitrite tlissiilved in a snia11 voluiiie ( I f water. Stirring :md c~oolingwere rimtinned for 15 inin. :iftt.r :ill the sodium nitrite had 1)eeii added. The diazoniiim solutioii w:ib* udded dropwise with stirring tu :i refluxing solution of 910 nil. of sulfuric acid in 6hO 1111. of water. Stirring and he:tting were w r i tinried further for 15 niiii. after :ill the tli:tzoriiurii sollitinn hati been :tddetf. The 1iiixtiii-e was r o i i l e d :ml cxtr:ictetl sever:il tinies with 1)enzerie. The I)enzeiie solutioii was wished with I O ' si~dirirrilij.tlr~i\itlc~ :111(1 t h ~ with n wntcar i:iitil :i(I:ienlis .ir.:ishw t h c b
Se p t em her. 1963
THYROMIMETICS. I
359
moved by filtration. The filtrate was placed in a separatory were neutral. The aqueous layers were combined and acidified funnel and the organic layer was separated. After washing with with dilute hydrochloric acid. The resulting phenol, if a solid, water, 10% sodium hydroxide, and again with water the benwas filtered and recrystallized: if a liquid it, was extracted into zene solution was dried over sodium sulfate and distilled. The benzene and the benzene solution was washed with water, dried residue was crystallized by trituration with solvent or was chroover magnesium sulfate, and evaporated. The residue was then matographed as described under route 4. distilled in i'acz(o. Preparation of IVa-h and XIa-c (Tables V and VI).-A misPreparation of Substituted Di-( p-anisy1)iodonium Iodides ( V ) ture of I11 or S in a solution made up of equal volumes of hy(Table 11). Method l.--A solution of iodyl sulfate20 prepared driodic (hydrochloric for S)and acetic acids (20 ml./g. of 111 or froni 0.08 iiiole nf iodine and 0.18 mole of iodine pentoxide in 500 X ) was heated under reflus for 4 hr., cooled, and poured into -1 nil. of :wetic acid was cooled with stirring to 15". The requisite volumes of ire-water. Aqueous sodium hydroxide was added t o anisole (0.2 ninle) was added dropwise while the temperature p H 5-6 and the precipitated solid was cooled, filtered, washed was maintained at 15' by intermittent cooling. Cooling was diswith water, and recrystallized. continued and the solution was allowed to warm t o room temPreparation of XId.-A suspension of 3 g. (4.6 mmoles) of S d perature as the iodyl sulfate dissolved (about 2.5 hr.). The in 35 ml. of acetic acid and 35 ml. of h>-drochloric aclid was heated mixture was filtered to remove a small amount of insoluble mateand stirred under refius for 2 hr. During this time the solid disri:11 and the filtrate was diluted with a large volume of water solved and reprecipitated. The mixture was cooled, diluted with containing excess potassiuni iodide and a little sodium bisulfite. water, and adjusted t o p H 5 with 40% sodium hydroxide. The The solid which separated upon cooling was filtered, washed with solid was filtered, washed with water, and recrystallized from ether, and recrystallized. aqueous acetic arid to give 1.2 g. of amide ( S I e ) , m.p. 250-251" Method 2.-To a solution of iodine trifluoroacetate?' in 50 ml. dec. of acetic8 anhJ-dride cooled to - 10" was added a solution of the A mixt,ure of 700 mg. of S I e in 25 nil. of acetic acid and 25 ml. required anisole (0.2 molej in n mixture of 80 ml. of acetic of hydrochloric acid was refluxed for 20 hr. (the solid never anhydride, 15 ml. of trifluoroacetic acid, and 0.5 ml. of water completely dissolved). The mixture was cooled, and filtered to nt such a rate that the temperature was kept below -5". The give after drying 600 niy. of material, m.p. 246" dec. The maternkture was stirred an additional 15 min. a t -5' and then was rial was purified by two isoelectric reprecipitations; yield 400 stored in a refrigerator overnight. The following day the dark mg. of XId, m.p. 230-240" dec. brown misture was stirred for 3 hr. a t rooni temperature before Hydrolysis of 1IIi.-A mixture of 750 mg. of IIIi in 10 ml. of the solvents were removed a t 40' (1-2 mm.). After the residue hydriodic and 20 ml. of acetic acids was refluxed for 4 hr. The was dissolved in 350 ml. of n thanol, the methanolie solution product was isolated and purified as described for IVa-h; yield was diluted with 75 ml. of 10 sodium bisulfite and 100 g. of 400 mg. of 3,5-diiodo-or,-thyronine monohydrate, n1.p. 259-261 O potassium iodide in 600 nil. of water. A precipitate which soon dec. appeared was filtered, washed with a 6: 1 petroleum ether-ether ,4nal. C:ilcd. for C15€IIJ2?;OI.E120:C, 33.17; H, 2.78; I, misture, and recrystrdlized. Preparation of IIa-e and IXa-d (Tables111 and VI).-A solution 46.74. Found: C, 33.52; H,2.94; I, 46.95. Biochemical Screening.-The compounds were screened for ~~*~ of 0.045 mole of S-acetyl-:3!5-dinitrotyrosine ethyl e ~ t e r ' and their ability t o lon-er plasma cholesterol levels in rats fed a diet 0.045 mole of p-toluenesulfonyl c.hloride in 100 ml. of pyridine 7 'cholic acid. containing 2% cholesterol and 1 was heated on a steam bath for 10 min. with stirring. I or a L-Triiodothyronine ( L - T ~or) the test compounds were injected substituted phenol (for the preparation of ISa-d) (0.10 mole) was added and the solution WRS stirred under reflux for 2 hr. subcutaneously, once daily for 7 days to groups of 8 adult male The pyridine was removed I'n z'acuo and the residue was dissolved Sprague-llawley rats having a fasting body weight of 270-290 g. and fed a diet consisting of 2 7 , cholesterol> 1Tccholic acid, 4% in c~hloroforni. The chloroform solution was washed successively Alphacel, 47$ vitamins and minerals, 20'3 protein, 207, hydrowith dilute hydrochloric acid: water, 10% sodium hydroxide, genated fat, and 49% carbohydrate. Appropriate controls were and again with water. The chloroform solution was dried, the also run. The animals were fasted for 18 hr. on the 7th day, and solvent was removed, anti the residue was recrystallized. Preparation of IIIa-e and Xa-d (Tables IV and VI). Route A. sacrificed by decapitation on the 8th day. Blood collections -A solution of I1 or I S (0.015 mole) in 150 ml. of acetic acid was and cholesterol determinations were made in a manner similar to that reported previously.2 The results are shown in Table reduced in a Parr apparatus in the presence of 1.5 g. of 1075 Pd/C VI1 and are expressed in terms of L-T~ having an arhit,raryvalue of under an initial pressure of 3 - 1 at,m. of hydrogen. When the reduction was complete, the catalyst was removed by filtration 1. and the filt,rate was added to a stirred, cooled nitrosyl sulfuric acid solution (prepared by slowly adding 5.3 g. of sodium nitrite t o a dose of L - T ~ which decreases plasma total mixture of 125 nil. of sulfuric acid and 50 ml. of acetic acid at cholesterol a t least 38 nig./100 mL26 activity = 60-70') a t such a rate that the temperature was maintained a t dose of test compound which lowers plasma total 0-5". .4fter all the amine had been added the tetrazonium cholesterol t o a comparable extent solution was stirred and cooled an additional hr. It was then added rapidly to a stirring mixture of 13.2 g. of sodium iodide, TABLEVI1 16.5 g. of iodine, and 3.0 g. of urea in 275 nil. of water and 275 ml. PLASMA CHOLESTEROL VALUES of chloroforni. Stirring was continued for 1-2 hr. nt room temCmpd. No. .irtiri t y" perature and the layers were separated. The aqueous layer was extracted several times with chloroform and the combined chloroIVa-DL 0.50 forni phases were washed in turn with water, 1072 sodium biIVb-DL 1 .00 sulfite, water, 5% sodium bicarbonate, and water. After drying IVb-D 0.15 over calcium chloride the chloroform solution was distilled. IVb-L 1.30 The residue was purified either by recrystallization or by elution IVc-L 0.50 with chloroform from a column packed with Woelm acid alumina 1Vd-m .35 (anionotropic, grade 1). Evaporation of the chloroform effluents IVe-DL < ,001 yielded a material which was crystalline or which crystallized upon the addition of solvent. IVf-DL 07 Preparation of IIIa-L and IIIf-i (Table IV). Route B.-A IVg-DL .03 mixture of 0.018 mole of T', 0.01 mole of N-acetyl-3,5-diiodotyrIVh-DL < ,001 osine ethyl e ~ t e r , ~1.5 5 ml. of triethylamine, and 0.1 g. of copper XIa-DL .04 powder in 120 ml. of methanol was stirred vigorously a t room XId-DL .03 temperature for 24 hr. The mixture was filtered and the filtrate Bctivity is expressed in terms of L-T~having an arbitrary was evaporated t o a sirup. The sirup was dissolved in benzene value of 1. and the benzene solution was shaken for 5 min. with dilute hydrochloric acid. Precipitated triethylamine hydrochloride was reQ
(24) J. C. Clayton, C . I'. H. Green, and B . .i. Hems, J . Chem. Soc., ZAG7 ( 1 9.5 I ) . (2.5) .J. H. Barnes, E . T.Burrows, J. Elks, B. .i. Hems, and A . G . Long, i b i d . , 2821 (1930).
(26) I t has been shown statistically using pooled samples from thyromimetic-treated and control animals that a plasma total cholesterol difference of 38 mg./100 ml. is required for significance ( P = 0.01).* A dose of 1.5.3.0 ag./kg./day of L-TX consistently causes such a depression.
'I'hyromimetics. 11. The Synthesis and Hypocholesteremic Activity of Some 0-Diethylaminoethyl Esters of Iodinated Thyroalkanoic Acids
;Ilthougli tlic wlatioiisliip t)etu-oeii seruiii cholwtcrol l t ~ i - c ~and l . ~ tliv occiiri'riice of atliri~osrlcrosishas not hceii c~oiicliisiwlytlciiioiistrated. the iiiiplicat ioiis ai' *3'-1*0111 OPYI ~ 0 1 i l p 0 ~ lSI11 ld \\ as plepal'('tf i i y i l i L : tlir secju~iicc~ ot i,eactions &on ii iii Chart I. Ethyl 3 , . 5 - d i i o d o - ~ - ( : 3 - i s o p r o p y l - l - n i e t h o x y p ~ plieiiylacetate 1X1-1)11as fiist prepared using a ptocedure (XI1- S\' -+ X1-I) siiiiilar to that reported by Wilkinsoiil in the preparatioii of :1,3-diiodothyroacctic acid. Thc iiitcriiiediatc XT'I i r a s prepared suhsequeiitly TI itliout isolation mol expediently from thc iodoiiiuiii ialt ST'II as showii (XT'II + XVI) iibiiig the method of Ziegler aiid X a r r Basic hydrolpis of XVI yielded t h e methoxy acid S I X which in turn could be coii\-citcd to the hydroxy acid XI'III 011 treatnient u i t h a mistui(3 of acetic aiid hydriodic acids. The acid XVIII. lro\vever, M ab ally prepared diwctly from S Y I a> s l i o ~ ~ nTreatment . of the acids S V I I I aiid X I S \\ itli ~-diethylamiiioethyl chloride a5 described yielded thc corresponding basic esters XI11 and XX. I'iifoituiiately, we were unable to purify XX to the poiiit \\ lipre satisfactory niialytical data could be obtained. Those 4'-iwthoxy acids \\-hose syntheses had not beeii repoitecl n ere readily prepared using dimethyl wlfate aiitl a c j i i r w i i h sodium hydroxide (Table 11).
-
(1
!>.& (1962).
(9) C . 11. L)uncan a n d AI. AI. Best, A m . .I. C'Liit. .\-utv.,10, 29; i l Y t i l ) . (10) 13. Blank, F. R. Pfeiffer, C. A f . Greenberg, and J. 1'. K e r n i n . .1.M f d . ('/tern., 6 , .J.-,-t '19831.
1 1 ) If J I o ~ r n . i t i oand kI l ' ~ ~ l d l c L cf , i r m Bel , 71, 1614 i l S ? h ' (12) J. I I TT Ilkinwn, Biorhem J , 63,601 (1956) I I I \ TI Z l e g i t I a n l l (' \ r u r J O i g f ' i i p m , 27, '3335 ,1962)
