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COBIMUNICATIONS TO THE
acid with ethoxyacetylene in the presence of mercuric salt catalysts are under investigation. lye have already shown that adenosine-5' phosphate (as the pyridinium or triethylammonium salts) in methanol solution, reacts with ethoxyacetylene (in the presence of Hg++ catalyst) on standing overnight to give the monomethyl ester of AMP. This product, obtainable in quantitative yield, was characterized by comparison with a sample prepared by Khorana's dicyclohexylcarbodiimide techniquelo using two chromatographic systems (2-propanolammonia-water, 7 : 1 : 2 ; butanol-acetic acid-water, 5 : 2 : 3) and two paper electrophoretic systems (0.1 .li K2HP04: 0.1 Jf KH2P04).
Vol. 82
EDITOR
I
I1
I11
(ii) Reaction of equimolar amounts of anthracene, dimethyl fumarate and aluminum chloride dissolved in dichloromethane a t room temperature was complete in less than two hours. When the relative molar concentration of aluminum chloride was increased to two, reaction was complete in less (10) XI. Smith, J. G. Irloffatt and H. G. Khorana, THISJ O U K K A L , than 5 minutes. A quantitative yield of the Diels80, 6204 (1958). .%lder adductg was obtained in each case. The reac(11) This work was supported by U. S. Public Health Service G r a n t , tion in the absence of aluminum chloride when carRG-3789(CG). ried out in boiling dioxane requires 2-3 daysg and COSTRIBUTION KO. 1630 FROM affords a less pure product. THESTERLING CHEMISTRY LABORATORY~~ YALEUNIVERSITY HARRYH. U'ASSERMAX (iii) Reaction of equimolar amounts of anthraSEK HAVEN,CONX. DAVIDCOHES cene, p-benzoquinone and aluminum chloride disRECEIVED JUSE 27, 1960 solved in dichloromethane a t room temperature was complete in less than 15 minutes, giving the 1: 1 ACCELERATION O F THE DIELS-ALDER REACTION adductlo in 907, yield. ]$Then the relative molar A.LLTM.I.XGTM. %sLQ&T.BD concentration of arrthracene-was increased- to- two; Sir: there was obtained in 90% yield the previously 5.90 p , Slthough catalysis of the Diels-Alder reaction by unknown bis-adduct, m.p. 230" dec.,X $:ic'z acids' has been reported, the influence of catalysts identified by its oxidation to the corresponding and condensing agents on the rate of this reaction quinone.'O Formation of the bis-adduct did not has been held to be smalL2 Our observation of the occur in boiling xylene in the absence of aluminum acceleration by aluminum chloride of the rearrange- chloride. (iv) Reaction of equimolar amounts of 2,3ment of a dicyclopentadien-&one derivative to a dicyclopentadien-1-one derivative, and the pro- dimethylnaphthalene, maleic anhydride and aluposal that this type of reaction is related to the minum chloride in dichloromethane a t room temDiels-Alder reaction, * has led us to investigate the perature was complete in cu. 4 hours. h 1 : 1 adduct effect of aluminum chloride on the rate of the latter m.,p. 175-1'7s" dec., was obtained in 40Y6 yield; reaction. We have found that in appropriate cases this is assigned structure 11, since on treatment with (oide i n f r a ) , the presence of one or more molar boiling methanol it was converted to an acid ester, equivalents of aluminum chloride can bring about C15H1R04,m.p. 154-185", XEf;c'2 5.75, 5.S3 p , which remarkable acceleration of the Diels-Alder reaction. gave with bromine and aqueous sodium carbonate a bromolactonic ester, CliHliOIBr, m.p. 191.5-192", The following cases are illustrative. c l z 5.75 p.ll The same adduct has been (i) Equimolar amounts of anthracene, maleic X ~ ~ ~ 3.60, anhydride and aluminum chloride were dissolved in obtained previously by heating 2,3-dimethyldichloromethane a t room temperature to give a naphthalene (1 mole) and maleic anhydride (30 solution 0.0625 M in each; the progress of the reac- moles) in a sealed tube at 100" for 2 1 hours.12 tion was followed by infrared spectroscopy, which Infrared spectr a1 examination of the crude product showed that reaction was complete in 1.5 minutes. formed under either set of reaction conditions indiThe reaction mixture was then poured onto ice, cated the presence of another adduct, presumably giving a quantitative yield of the Diels-Alder ad- 111; this was formed to a greater extent in the abd u d 5 From extrapolation of the rate curve for sence of aluminum chloride. In addition to the cases cited in detail above, evithe reaction under equivalent conditions of temperature and concentration in the absence of aluminum dence has been obtained for the acceleration by chloride it is estimated that 4800 hours would be re- aluminum chloride of the following Diels-Alder reactions : anthracene and diethyl maleate, diquired for 957c completion.6 ethyl fumarate, citraconic anhydride, or dichloro(1) A. Wassermann, J. Chem. Soc., 618, 623 (1942); W. Rubin, maleic anhydride (in dichloromethane) ; cyclopenH . Steiner and A. Wassermann, ibid., 3046 (1949); A. Rodgman and G. F. Wright, J . Org. Chem., 18, 465 (1953); L. E. Gast, E. W. Bell tadiene and $-benzoquinone (in carbon tetraand H. M . Teeter, J . Am. Oil Chemisls' Soc., 33, 278 (1956). (2) K. Alder in "Newer Methods of Preparative Organic Chemistry," Interscience Publishers, Inc., Piew York, N.Y., 1948, p . 404; C. K. Ingold, "Structure and Mechanism in Organic Chemistry," Cornell University Press, Ithaca, N. Y., 1953, p. 720. (3) P. Yates and P. Eaton, Tefrahedron Leflers, No. 11, 5 (1960). (4) R. B. Woodward and T. J. Katz, Tetrahedron, 6, 70 (1959). ( 5 ) E . Clar, Ber., 64, 2194 (1931). (6) T h e reaction of anthracene, maleic anhydride a n d aluminum chloride in benzene solution a t 60-70° has been reported t o yield 8-(9-anthroyl)-acrylic acid.7 We have found t h a t this compound should be reformulated8 as CirHirOi and t h a t it has structure I, formed
pia a n initial Diels-Alder reaction followed by a Friedel-Crafts condensation with the solvent. (7) H . G. Oddy, THISJOURNAL, 46,2156 (1923). (8) Satisfactory elementary analyses for this compound and all new compounds here reported have been obtained. (9) W. E. Bachmann and L. B. Scott, ibid., 70,1458 (1948). (10) E . Clar, Ber., 64, 1676 (1931). (11) CJ.' K. Alder and G. Stein, Ann., 604, 216 (1933); 614, 1 (1934). (12) hl. C. Kloetzel and H . I,. Herzog, THIS J O U R N A L , 73, 1991 (1950).
COMMUNICATIONS TO THE EDITOR
Aug. 20, 1960
4437
mide lines decrease in relative intensity as the amount of alkyllithium in the solid increases, and become weaker than the “complex” lines in solids with LiBr : C4HgLi ratios less than 2. These X-ray data indicate that the solids are probably mixtures of lithium bromide with a 1 : l complex, CdHeLi. LiBr. The alkyllithium-lithium halide complexes appear to be quite different in their reactivity and properties from the ternary complexes of aryllithium, ether and lithium halide previously reported by Talalaeva and K o c h e ~ h k o v . ~The butyllith(13) Following our suggestion, Mr. Kirby Scherer of these Laboratories has used aluminum chloride in dichloromethane to effect a ium-lithium bromide complex is rapidly hydrofacile Diels-Alder reaction between anthracene and 2-cyclopentenone a t lyzed by water with the liberation of butane, but the room temperature; in t h e absence of aluminum chloride t h e reaction rate of reaction with oxygen appears to be quite in boiling xylene requires 5-6 days. slow. Only partial decomposition was observed (14) N. S. F. Fellow, 1959-60. DEPARTMENT OF CHEMISTRY PETERYATES when the complex was exposed to laboratory air in HARVARD UNIVERSITY PHILIPEAT OX]^ an open beaker for three hours. The complex is CAMBRIDGE 38, MASSACHUSETTS also more stable thermally than is n-butyllithium. RECEIVED JULY 7 , 1960 The latter compound undergoes rapid decomposiwhile the comtion a t temperatures above SOLID COMPLEXES OF ALKYLLLITHIUM plex is less than 50% decomposed in one hour a t COMPOUNDS WITH LITHIUM HALIDES’ 160”. Sir: The solid complexes, when suspended in pentane We wish to report the preparation of a series of or benzene, are quite unaffected by Michler’s ketone relatively unreactive solid complexes of alkyl- (negative Gilman test7 after 30 hours contact time). lithium compounds with lithium halides. Materials The addition of ether apparently destroys the comso far obtained have apparent formulas RLi.nLiX, plex, and an immediate Gilman test is obtained. where n is from 1.4 to 6, but these compositions Thus alkyllithium compounds can be deactivated appear to be mixtures of a 1: 1 complex RLi.LiX by conversion to lithium halide complexes, and with excess lithium halide. In marked contrast to then regenerated in the form of conventional oralkyllithium compounds, the complexes can safely ganolithium reagent solutions upon addition of be exposed to air, and can be handled in the labora- ether. tory with no more precautions than those used with No evidence has yet been obtained concerning the other compounds mildly sensitive to moisture and structure of the complexes. Two limiting ionic oxygen. structures, Li+[RLiX]- and [LizR]+X-, could be The complexes are produced by carrying out the considered, along with an intermediate electronwell-known coupling reaction (1) between alkyl- deficient polymeric structure. The structures of the lithium compounds and alkyl halides. In a hydro- complexes are under investigation, along with furcarbon solvent ther reactions and alternate methods of preparation.
chloride). Thus, this procedure promises to be of considerable utility for the acceleration of a wide range of Diels-Alder reactions.I3 Limitations are imposed by the instability of some dienes and dienophiles under the reaction conditions and by the preferential occurrence of Friedel-Crafts reactions in some cases. We gratefully acknowledge a grant from the General Chemical Division, Allied Chemical Corporation, which defrayed the cost of this investigation.
RLi
+ R’X
---f
LiX
+ RR’
(1)
the precipitate which forms is not simply lithium halide, but rather is a complex of lithium halide with the alkyllithium compound. The proportion of alkyllithium in the resulting solid varies with the conditions under which coupling is carried out.2 To isolate the solid complex, the precipitate froni reaction (1) is filtered, washed with pentane, and dried in ‘ ~ ‘ a c u o . ~By this method complexes have been prepared from n-butyllithium and lithium bromide or iodide, from ethyllithiuni and lithium bromide, and from cyclohexyllithiunl and lithium bromide. In the n-butyllithium-lithium bromide system, which has been studied in the greatest detail, solids have been obtained with LiBr : C4HgLi ratios of 5, 3.3, 2.0, 1.5, and 1.4. Powder X-ray diffraction patterns for all of these compositions show both lithium bromide lines and new lines characteristic of the c o ~ n p l e x . ~The lithium bro(1) This research was supported by the United States Atomic Energy Commission under contract No. A r ( l l - l ) - 6 4 , Project No. 18. ( 2 ) T h e coupling reaction may not be necessary for the synthesis of the complex, b u t m a y only provide a convenient method for slow generation of lithium halide in a solution of a n alkyllithium compound. (3) Preparations of both alkyllithium compounds and complexes were carried o u t in a drybox in a n atmosphere of d r y argon. (4) d spacings in .&.: 16.3 ( s ) ; 8.8 ( m ) ; 5.7 (N); 4.40 (w): 4.07 (N); 3 87 ( s ) ; 3.30 (s); 2.89 (s); 2.55 (w);2.43 (w); 2.20 (m); 1.89 (m).
( 5 ) T. V. Talalaeva and K . A. Kocheshkov, Doklady A k a d . N a u k S . S . S . R . ,104, 260 (1955). (0) D . Bryce-Smith, J . Cheiiz. Suc., 1712 (1955); K . Ziepler and H. G. Gellert, A n n . , 567, 179 (1950). (7) H. Gilman and F. Schulze, THISJ O U R N A L , 4’7, 2002 (1925).
DEPARTAXEST OF CHEMISTRY UNIVERSITY OF LVISCONSIS LVILLIAMGLAZE MADISON 6, WISCONSIN ROBERT WEST J U N E 17, 1960 RECEIVED ~~
4-PHOSPHORINANONES
Sir: Several recent papers attest to the lively interest in heterocyclic compounds containing only carbon and phosphorus in fivemeinberedl and six-mernbered rings.2 We wish to report the preparation of a new class of six-membered carbon-phosphorus heterocyclic compounds, the 4-phosphorinanones (I), whose ring-carbonyl group affords an entry into an otherwise difficultly accessible area of organophosphorus chemistry. (1) E. Howard and R. E. Donadio, Dissertation Abstracts XX, No. 2, p. 495, (1959), University Microfilms, Inc.; F. C. Leavitt, T. A. Manuel and F. Johnson, THIS J O U R N A L , 81, 3164 (1959); E. H. Braye and W. Hubel, Chem. and I n d . , 1250 (1959). I. G. M . Campbell and J. K . Way, P r o c . Chem. Soc., 231 (1959); F. G . M a n n , I. T. Millar a n d H. R. Watson, J . Chem. Soc., 2516 (19.58). (2) R . C . Hinton and F. G. Mann, i b i d . , 2835 (1959).
