NOTES
3410
tallized from benzene as small, yellow prisms, 0.45 g., m.p. 180181’. The yield of 1,2,3,4,6,7,12,12b-octahydro-2-oxoindolo[2,3-a]quinolizinewas 357,. The column was further developed with ether, chloroform, and methanol, but the few milligrams of oily product obtained could not be characterized.
P
Synthesis of 5-Alkyl-5,lO-dihydro-lOphenylphenophosphazine GEORGE BAUM,HELENA. LLOYD,AND
VOL. 29 R
R
A
I
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I
CHRIST TAMBORSKI
b
The Polymer Branch, A‘onmetallic Materials Division, Air Force Materials Laboratory, Wright-Patterson A i r Force Base, Ohio Received M a y 1 , 1964
phenylamine could be used as the intermediate, (2) whether the secondary amine could be alkylated to the Few references to a 5,lO-dihydrophenophosphazine’ tertiary amine by more convenient synthetic procering systeni (I) appear in the literature. Michaelis dures, and (3) whether a di-Grignard of the N-alkyl-2,2’and Schenk2 in 1890 reported a compound corresponddihalodiphenylamine could be prepared. ing to CI2HloNOPobtained by hydrolysis of the reacThe 2,2‘-dichlorodiphenylainine was prepared by the tion product of phosphorous trichloride and diphenylChapman rearrangement in the manner described in amine. Sergeev and KudryashovS later proposed that the literatures for the 2,2’-dibromodiphenylamine. the material was 5,lO-dihydro-10-hydroxyphenophos- The physical properties for the intermediates are rephazine (11),but Haring4has assigned structure I11 on ported in the Experimental section. the basis of its infrared spectra. Jones and Mann5 Jones and Mann5 were unsuccessful in their attempts to alkylate the 2,2’-dibromodiphenylamine. Gilman and Zuech’ successfully affected alkylation by a hydrogen-metal interchange of the secondary amine with methyllithium followed by treatment of the organolithiuni intermediate with dimethyl or diethyl sulfate. In I our studies we were successful in alkylating either the A-1-1 0” ‘H H dichloro or dibromodiphenylaniine by a method which I I1 rn involves metalation with sodium hydrideg followed by were unable to obtain 5,lO-dihydrophenophosphazine alkylation of the sodium intermediate with an alkyl iodide. The yields and physical properties of the comderivative from 2,2’-dilithiodiphenylamine and phenylpounds prepared are reported in the Experimental secdichlorophosphine and instead obtained a viscous tion. orange liquid of unknown composition.6 It seemed, Preparations of the X-alkyl-2,2’-dilithiodiphenyltherefore, in order to obtain the desired phenophosphaamine were attempted on both the dibromo and dichloro zine derivative, a tertiary amine, N-alkyl-2,2’-dihalointermediates. The N-methyldibromodiphenylaniine diphenylamine, would be required. Recently Gilman yielded t.he dilithio intermediate which reacted readily and Zuech,’ who have further developed this cyclization with phenyldichlorophosphine to yield the desired prodreaction and have shown its versatility, synthesized the uct, 5-niethyl-lO-phenyl-5,lO-dihydrophenophosphazine, Si, Ge, and Pb analogs of this heterocyclic system. in 58.0% yield. However, the N-alkyl-2,2’-dichloroSimilar organometallic reaction schemes have been the diphenylamine would not form the desired 2,2‘-dilithio subject of several patents.8 intermediate.10 The di-Grignard of S-ethyl-2,2’-diWe now wish to report our observations in the synbromodiphenylamine likewise formed readily and carthesis of some substituted 5,lO-dihydrophenophosphabonation of this organometallic yielded the acid Nzine compounds via a cyclization reaction of diorganoethyl-2,S’-dicarboxydiphenylaniine in 55.8% crude metallic conipounds with difunctional phosphorus comyield. React,ion between the di-Grignard and phenylpounds. It was of interest in our studies to determine dichlorophosphine, however, yielded the cyclic 5,lO(1) whether the inore readily available 2,2’-dichlorodidihydrophenophosphazine in only 28% yield. Prepa(1) The nomenclature employed herein on the 5,10-dihydrophenophosration of the di-Grignard reagent from the S-alkyl-2,2’phazine ring system was recommended by the editorial staff of Chemical dichlorodiphenylaniine was considerably inore difficult. Abstracts. (2) A . Michaelis and K . Schenk, Ann., 260, 1 (1890). In ether or tetrahydrofuran, the reaction could not be (3) P. G. Sergeev and D. G. Kudryashov, J . Cen. Chem. U S S R , 8 , 266 initiated by iodine, ethyl bromide, ethyl iodide, or (1938). ethylene dibromide. The di-Grignard was finally pro(4) M. Haring, H e l u . Chim. Acta, IS, 1826 (1960). ( 5 ) E. R. H . Jones and F. G. Mann, J . Chem. Soc., 786 (1956). duced in small yield by a modification of the Blues and (6) T h e difficulty encountered by Jones and Mann was attributed t o the Bryce-Smith procedure” (see Experimental section). use of a secondary amine, 2,2’-dihromodiphenylamine,with its multiplicity
B
IT
B
o k D aNs aN$) a*
of reaction possibilities when treated with butyllithium and phenyldichlarophosphine. (7) (a) H. Gilman and E. A. Zuech, Chem. Ind. (London), 1227 (1958); 82, 2522 (1960); ( 0 ) (b) H . Gilman and E. A. Zuech, J . A m . Chem. SOC., H. Gilman and E. A. Zuech, J. Org. Chem., 26, 2013 (1961). (8) (a) R . E. Jones and D. Wasserman, U. S. Patent 3,065,251(1962); (b) J . Kollonitsch, U. S. Patent 3,120,565 (1964).
(9) Sodium hydride dispersion, 50% in mineral oil, was used; Metal Hydrides, Inc., Beverly, Mass. (10) Aromatic chlorine compounds seldom undergo a metal-halogen interchange: H . Gilman and 9. LM.Spats, J . A m . Chem. Soc., 63,1553 (1941); H. Gilman and F. W. Moore, ibid.,62, 1843 (1940). (11) E. T. Blues and D. Bryce-Smith, Chem. Ind. (London), 1533 (1960).
NOVEMBER, 1964
NOTES
The di-Grignard thus prepared was allowed to react with phenyldichlorophosphine to yield the desired cyclic 5,lO-dihydrophenophosphazine in only 14.2% crude yield. Experimental All reactions involving organometallic intermediates were carried out under an atmosphere of dry, oxygen-free nitrogen. Melting points are uncorrected. 2,2'-Dichlorodiphenylamine.-This compound was prepared by the same procedureS outlined for the synthesis of 2,2'-dibromodiphenylamine. The physical properties and yields of the intermediates isolated are: N-o-chlorophenylbenzimidoyl chloride, b.p. 146" (0.5 mm.), 75%; o-chlorophenyl N-o-chlorophenylbenzimidoate, m.p. 67.5-68.5", 59%,; N-benzoyl-2,2'-dichlorodiphenylamine, m.p. 152-153', 827,; 2,2'-dichlorodiphenylamine,m.p. 83.5-84", 897,. N-Methyl-2,2'-dichlorodiphenylamine.-A solution of 2,2'dichlorodiphenylamine (2.4 g., 0.01 mole) in 10 ml. of tetrahydrofuran was added dropwise to a mixture of sodium hydride (0.24 g., 0.01 mole, 50% in mineral oil) and methyl iodide (1.4 g., 0.01 mole) in 10 ml. of tetrahydrofuran maintained under a dry nitrogen atmosphere. The only evidence of reaction was a slow gas evolution. Stirring was continued for 50 min. The mixture was then heated to reflux and held a t that temperature for 2 hr. The excess sodium hydride was decomposed by the addition of a small amount of methanol and the tetrahydrofuran was removed by distillation in a slow stream of nitrogen. The brown residue was dissolved in petroleum ether (b.p. 90-120") and washed with 20 ml. of water. The water layer was extracted with two 20-ml. portions of ether and the combined ether and petroleum ether extracts were dried over anhydrous sodium sulfate. By repeated concentration, cooling, and filtration there was obtained 1.93 g. (76.57,) of the desired product, m.p. 81-83'. Recrystallizat'ion from petroleum ether (b.p. 30-60") raised the melting point to 85.5-86 O. Anal. Calcd. for CllHllCIYN: C, 62.00; H, 4.37; C1, 28.12. Found: C, 61.62; H, 4.40; C1, 28.16. When the reaction was repeated on a larger scale a yield of 857, was realized. N-Methyl-2,2'-dibromodiphenylamine.-Following the above procedure, the S-methyl-2,2'-dibromodiphenylamine was prepared in 887, yield, m.p. 104-106" (lit.7cm.p. 106-109"). N-Ethyl-2,2'-dichlorodiphenylamine .-Following the above procedure, the ethyl derivative was prepared in 74.57, yield, m.p. 52-53'. Anal. Calcd. for C1dH1sClpIi: C, 63.37; H, 4.92; C1, 26.64; N, 5.26. Found: C, 63.35; H , 5.16; C1, 26.10; N, 5.25. N-Ethyl-2,2'-dibromodiphenylamine.-Following the above procedure the N-ethyl-2,2'-dibromodiphenylaminewas prepared in 83YGyield, m.p. 72-74" (lit.7bm.p. 72-74'). N-Ethyl-2,2'-dicarboxydiphenylamine .-A solution of N-methyl-2,2'-dibromodiphenylamine (10.67 g., 0.03 mole) in 50 ml. of freshly distilled tetrahydrofuran was slowly added to magnesium (1.70 g.-atom) in 20 ml. of tetrahydrofuran. The reaction was initiated with a few drops of ethyl bromide. The reaction was refluxed for 1 hr. and then poured over Dry Ice in diethyl ether. The mixture was acidified with 10% hydrochloric acid, the organic layer was separated and extracted with 5% potassium hydroxide. The water extracts were acidified with 10cj;, hydrochloric acid and extracted with ether. The ether layer was separated, dried over anhydrous sodium sulfate, and the solvent was removed to give 7 g. of a viscous oil. The oil was recrystallized from methanol to give 4.77 g. (55.8% crude) of product, m.p. 129-143". Two recrystallizations raised the melting point to 148.5-151 '. Anal. Calcd. for Cl,HlsNOl: C, 67.36; H, 5.30; N, 4.91; mol. wt., 285.3. Found: C, 67.41; H, 5.30; N, 5.05; mol. wt., 285. Preparation of 5-Methyl-10-phenyl-5,lO-dihydrophenophosphazine via Butyllithium Reaction .-A solution of n-butyllithium (0.04 mole) in diethyl ether was added a t ice-bath temperature to N-methyl-2,2'-dibro1nodiphenylamine(6.3 g., 0.0191 mole). Color Test IIlZwas negative after 1 hr. To the reaction mixture was added phenyldichlorophosphine (3.3 g., 0.018 mole) in 10 ml. of diethyl ether. The reaction mixture was stirred overnight a t room temperature, hydrolyzed, and extracted with ethyl (12) H. Gilman and J. Swiss, J . A m . Chem. Soc., 62, 1847 (1940).
341 1
acetate to give 3.1 g. (567,) of pale yellow crystals, m.p. 154157". Recrystallization from anhydrous ethanol raised the m.p. to 159-160". Anal. Calcd. for C19H16NP: C, 78.88; H, 5.57; N, 4.84; P , 10.71. Found: C, 78.92; H, 5.56; N, 4.85; P , 10.51. The 5,10-dihydrophenophosphazine formed a monomethyl iodide adduct in ethanol, m.p. 295-297' dec. Anal. Calcd. for Cp0H1gINP: C, 55.69; H, 4.44; I , 29.42; N, 3.25; P, 7.18. Found: C, 55.78; H, 4.43; I , 29.04; N, 3'.31; P , 7.23. Preparation of 5-Ethyl-10-phenyl-5,lO-dihydrophenophosphazine via Grignard Reaction 1.-A solution of N-ethyl-2,2'dibromodiphenylamine (10.67 g., 0.03 mole) in 45 ml. of freshly distilled tetrahydrofuran was added dropwise to magnesium (1.7 g., 0.07 g.-atom) in 5 ml. of tetrahydrofuran under a stream of dry nitrogen. The reaction was initiated with a few drops of ethyl bromide. After addition was completed, the reaction was refluxed for 2 hr. To the reaction mixture phenyldichlorophosphine (5.0 g., 0.028 mole) in 30 ml. of tetrahydrofuran was then added. Color Test I 1 3 was negative within 0.5 hr. The reaction mixture was refluxed overnight and then hydrolyzed by the addition of saturated aqueous ammonium chloride. Ethyl acetate was added; the mixture was filtered. The organic layer was separated and dried over anhydrous sodium sulfate, and the solvent was then removed to give a viscous oil which was recrystallized from 95% ethanol to yield 2.51 g. (27.57,) of product, m.p. 85-97'. Two successive recrystallizations from 9570 ethanol raised the melting point to 96.5-98.0". Anal. Calcd. for C2aHlaNP: C, 79.19; H , 5.98; N, 4.62. Found: C, 79.19; H, 5.95; N, 4.42. Preparation of 5-Ethyl-10-phenyl-5,lO-dihydrophenophosphazine via Grignard Reaction 11.-A few crystals of 1% were added to a slurry containing magnesium powder (0.72 g., 0.03 g.-atom), N-ethyl-2,2'-dichlorodiphenylamine (2.66 g., 0.01 mole), isopropyl alcohol (0.18 ml.), and freshly distilled tetrahydrofuran (5 ml.). The reaction was heated to 55" where slight frothing occurred and was then heated to 120' until the tetrahydrofuran was swept out. The reaction was cooled to 55" and isopropyl alcohol (0.20 ml.), tetrahydrofuran (5 ml.), and a few crystals of Ip were again added. After the initial frothing subsided an additional 25 ml. of tetrahydrofuran was added dropwise. After 2.5 hr., Color Test I was positive. To the reaction mixture was added phenyldichlorophosphine (1.70 g., 0.0095 mole) in tetrahydrofuran (17 ml.). The reaction was exothermic and Color Test I was negative after 45 min. The reaction was quenched with methanol and filtered. The methanol solution yielded a very gummy product which was extracted with 1 : 1 petroleum ether (b.p. 30-60") and methanol to give 0.428 g. (14.2%) of crude product, m.p. 82-97", Recrystallization from petroleum ether raised the melting point to 96-98'. (13) H. Gilman and F. Schulze, ibid., 47, 2002 (1925).
The Equilibrium Protonation and AcidCatalyzed Detritiation of Cyc1[3.2.2]azine1 ROBERTJ. THOMAS AND F . A. LONG Department of Chemistry, Cornell University, Ithaca, New Y o r k Received June 19, 1964
We have studied the equ'ilibrium protonation and acid-catalyzed detritiation of cycl[3.2.2]azine,I.* This inolecule possesses considerable resonance stabilization, undergoes electrophilic substitutioi~,~ and reversibly (1) Work supported by a grant from the Atomic Energy Commission. (2) T h e sample of I was kindly provided by Professor V. Roekelheide of the Department of Chemistry, University of Oregon, Eugene, Ore. (3) R. J. Windgassen, Jr., W. W. Saunders, J r . , and V. Boekelheide, J . A m . Chem. Sac., 81, 1469 (1959). (4) V. Boekelheide and T. Small, ibid., 83, 462 (1961).
