COMMUNICATIONS TO THE EDITOR
Oct. 20, 1963
3, which is given in Table I along with other pertinent data. The observed value is consistent with those for related azirine derivatives and suggests t h a t the scharacter of the @-carbonatom is approximately 34%. TABLE I CI3-H COUPLING COSSTANTS
3305 Rz \
Rz
--+RLLi+
R1-(!-CH2-Li
1
/
Rz C=CH,
Li I11
R1
R3 I
--+ RJ-C-C,HSR1
I1
lithium compound I , which is present initially in high concentration, should compete successfully in addition Compouid Group Jc"H. c.P.s." to the olefin; however, no products corresponding to a-Lactani 3 Ring C H 168 5 f 0 5 addition of I have been found. As a further test for 1-Bu 126 the elimination-readdition niechanisni, Zinimerman h~-Methylallenirnine* Ring C H ? 169 and Zweig4 obtained little, if any, reaction of p-tolylOlefinic C H z 162 lithium with a-methylstyrene using conditions under S-CHI 135 which 2-phenyl-2-(p-tolyl)-propyllithiumhad under2,2-Diniethylethylenimine King CHI 166 gone much rearrangement. E t h ylenirnine King CHz 168 1 f 0 5' \Ye wish to report some experiments pertaining to the 175 8 j, 0 5" Ethylene oxide King CH2 elimination-readdition mechanism for rearrangement 16Id Cyclopropane King CH, of 2,2,2-triphenylethyllithiuniand 2,2,3-triphenylproDetermined with neat liquid using a Varian A-60 spectrornpyllithiurn. A preliminary experiment, in which 1 , l eter. We are indebted t o Professor J. D. Roberts for a sample diphenylethene was added to about a half-molar equivaof this compound. E;. S. Mortirner, J . M n l . Spectry., 5 , 199 lent of 2,2,3-triphenylpropyllithium (1960). '! S.Muller and D. E . Pritchard, J . Chem. P h y s . , 31, in tetrahydrofuran 768, 1471 (1959). a t -65 f 5' and the mixture warmed to 0' for 10 miti. under the general conditions required for rearrangeAlthough individual items among this experimental ment,j gave after carbonation only 3% recovery of evidence and that cited earlier, taken one a t a time, 1,1-diphenylethene and much ill-defined polymeric can be rationalized reasonably well on the basis of one material. This experiment must be regarded as inor another of the alternative structures, consideration decisive, since the concentration of 1,l-diphenylethene of the whole of the data appears to lend substantial was doubtlessly much higher than that likely to exist support to the a-lactam structure. The results do not during rearrangement of 2,2,3-triphenylpropyllithium. rule out the possibility that a delocalized intermediate may be involved in some of the further reactions of 3.6 Accordingly, benzyllithium was prepared by the procedure of Gilman7 from benzyl methyl ether-a-CI4. Experiments exploring this possibility (among others) A tetrahydrofuran solution (130 ml.) containing I 1.2 are in progress. mmoles of radioactive benzyllithium a t - 63' was added (14) University of S e b r a s k a , Lincoln, Nebraska to 430 ml. of a tetrahydrofuran solution containing 2 3 . 8 CONTRIBUTION S o . 3005 HENRYE. BAUMGARTEN14 mmoles of 2,2,3-triphenylpropyllithi~m~ a t the same GATESA N D CRELLIXLABORATORIES OF CHEMISTRY temperature and the well stirred mixture was allowed ,CALIFORNIA INSTITUTE OF TECHNOLOGY to warm to 0' and kept a t this temperature for 30 niin. PASADESA, CALIFORNIA before carbonation.8 The initial specific activity of the VERY LABORATORY JAMES F. FUERHOLZER USIVERSITY OF NEBRASKA R.DAVIDCLARK starting benzyllithium was determined by carbonation LINCOLN, SEBRASKA ROBERTD. THOMPSONof a portion of the same preparation of benzyllithiurn RECEIVED JULY 19, 1963 and assaying the resulting benzoic acid. I n the following reaction sequence the activities of reactants and products are indicated below each compound assayed Carbanions. VI. The Mechanism of in units of microcuries per millimole. From this Rearrangement of Z,Z,Z-Triphenylethyllithium experiment it is obvious that the rearranged organoand 2,2,3-Triphenylpropyllithium lithium compound gained radioactivity a t the exSir: pense of the benzyllithium; therefore, very likely, A 1,2-shift of phenyl has been observed in 2,2,2CBH,C*HzLi + C8HbCHzC(CsHj)2CH2Li+ triphenylethyl derivatives of sodium, 1 , 2 potassium, and ( C8Ha)nCLiCHLHaCsH6 l i t h i ~ m .An ~ analogous migration of phenyl has been ob2 94 (None) CsHsCH2Li served in 2,2-diphenylpropyllithium and -potassium and / of phenyl in preference to p-tolyl in 2-phenyl-2-(p-tolyl)propyllithium.4 Finally, a 1,2-migration of benzyl has been observed in 2,2,3-triphenylpr0pyllithium.~ These rearrangements have been assumed, implicitly or COeH explicitly, to be intramolecular in character. 1.19 0.326 By analogy with recent work6on the lk'ittig rearrangea benzyl group in a triphenylpropyllithium (or ment of ethers, an elimination-readdition mechanism compound derived therefrom) exchanged with a seems possible. Thus, the organolithium compound I benzyl group of benzyllithium. The 1,1,3-triphencould eliminate an organolithium compound I1 to form ylpropyllithium produced, however, is not a t radioan olefin which could combine with IT in the inverse chemical equilibrium with the benzyllithium in manner to give the final product of rearrangement 111. the solution at the end of this experiment, since its The general argument4 in opposition to such a mechanism is t h a t if addition of organolithium compound I1 to (7) H. Gilman and H A. McSinch i b i d 8 6 , :372X (1961). H Gilman a n d G . L. Schwshks, ibid., 27, 4259 (1962) the olefin were possible, then the more basic organo'l
+
(1) E. Grovenstein, J r . , J . A m . Chem. Soc., 79, 4985 (1957). (2) H. E . Zimmerman and F. J Smentowski, i b i d , 79, ,5455 (19;77). (3) E. Grovenstein. Jr., and I,. P Williams, J r . , z b i d . , 83, 412 (1961). ( 4 ) H. E. Zimmerman and A Zweig, i b i t f . , 83, 1196 (1961). ( 5 ) E Grovenstein, Jr , and I-. P Williams. J r , i b i d . , 8 3 , 2.537 (1961). (6) U. Schoellkopf and W. Fabian, A n n . , 642, 1 (19611, U. Schoellkopf and 1) Walter, ibid., 664, 27 (1962). P. T . Lansbury and V . A. Pattison. J . A m Chem. Soc., 84, 4295 (1962): P T Lanshury and V. A Pattison, J . O r g . C h r m . , 27, 1933 (1962).
( 8 ) Th: concentrations of the organolithium compoun d s were determined by the douhlc titration t:chniqus [H. Gilman and A. H Hauhein, J . A m Chem. Soc., 6 6 , 1515 (1911)l. T h c radiochemical determinations were by thc wct combustion method 10 K. Nevillc. d i d . . 7 0 , X 5 O l i l 9 4 8 ] ] with the oxidizers prepared according to Van Slyke and ca-workers [ I ) I ) Van Slykc. J. Plazin, and J I< Weisiper, J Btol. C h e m . . 191, 2!N ( 1 9 > 1 ) ] . A vibrating-reed clectrometer (Applied Physics Corp , hiodel 31) wa5 used tu assay the radioactive carbon dioxide Benzoic acid-carhoxylLC'4 (fr
