Nov., 1944
1929
REARRANGEMENT OF ALLYLGROUPS IN AMINEOXIDES
organic bases was confirmed by preparing and identifying the hydrochlorides of the bases and by conducting mixed melting points of the salts with authentic samples prepared by treating p-toluenesulfonic acid with the appropriate base in ether.
hydroquinoline salt of p-toluenesulfonic acid. The 4-ester is very unstable. The p-toluenesulfonoxypyriridines were reduced to pyridinium and piperidinium p-toluenesulfonates, the 3-isomer being hydrogenated comSummary pletely and rapidly, the 4-isomer more slowly, and The 5-, 6-, 7- and 8-(~-toluenesulfonoxy)- the 2-isomer most slowly. The 2-(~-toluenesulfonoxy)-quinoline was more quinolines yielded primarily the corresponding 1,2,3,4-tetrahydro derivatives on catalytic hydro- rapidly reduced than the corresponding benzenegenation with a palladium catalyst, whereas the sulfonoxy derivative. 2- and 3-isomeric esters gave the lI2,3,4-tetra- RENSSELAER, N. Y. RECEIVED SEPTEMBER 12, 1944
[CONTRIBUTION FROM THE
DEPARTMENT OF CHEMISTRY,
COLUbfBIA UNIVERSITY]
Rearrangement of Allyl Groups in Dyad Systems. Amine Oxides BY ROGERF. KLEINSCHMIDT AND ARTHURC. COPE
Meisenheher has shown that allylmethyl- anionotropic shift, in which the GHcN(CH8) --+ 0 aniline oxide (I) rearranges readily on heating fragment separates as an anion and recombines with aqueous sodium hy$oxide to give O-allyl- through oxygen rather than nitrogen. We have N-methyl-N-phenylhydroxylamine (11). The re-investigated the rearrangement, in order to confirm the structures of the compounds conCHs CHa cerned and obtain evidence for the mechanism of I I the reaction. CsH6-N + 0 +C&Is-N--OCsHs I Oxidation of allylmethylaniline with perbenzoic CnHs acid gave the amine oxide, I, which rearranged (1) (11) rapidly in alkaline solution to the isomer, 11. structure of the isomerization product was estab- Preliminary attempts to synthesize I1 by an inlished by reduction with zinc dust and acetic acid to dependent method which would confirm its strucmethyladine and allyl alcohol, by hydrogenation ture were unsuccessful, but it was possible to synto 0-propyl-N-methyl-N-phenylhydroxylamine,thesize the 2,4-dinitro derivative of I1 by the and by hydrolysis with hydrochloric acid. The hy- sequence of reactions drolysis products which were isolated were methylKOH 2,4-(NOa)nCsHaC1 HzNOC~HS aniline, pchloro-methylanilhe, and acrolein. NH(COOC2Hs)OC3H:, (111) ( W Their formation was attributed to cleavage of I1 CHsN2 in two ways; into allyl alcohol and CsHsN(CH8)~ , ~ - ( N O I ) ~ C ~ H ~ S__t HOC~H~ C1 (which by rearrangement could give chloro07 methylaniline), and into methylaniline and acro~,~-(NOI)~C~H~N(CH~)OCIH~ lein. Allylethylaniline oxide and benzylmethyl(VI) aniline oxide2later were shown to rearrange in the Nitration of I1 with fuming nitric acid in glacial same way, although the structures of the isomeriacetic acid gave the same dinitro derivative, conzation products were not proved in these cases. Beyond calling attention to the similar mobility firming its structure. Benzylmethylaniline oxide (VII) also was preof allyl groups in allyl thiocyanate and in the allyl ethers of phenols and enols,8 Meisenheimer pared and rearranged by heating in alkaline solumade no commitment concerning the mechanism tion. The isomerization product proved to be 0of the rearrangement. Considering the analogy benzyl-N-methyl-N-phenylhydroxylamine, VIII. of tautomerism in triad and dyad systems, it Its structure was established by hydrolysis with seemed to us very probable that the isomerization dilute hydrochloric acid, which yielded bepzaldecould be explained as a rapid, thermal rearrange- hyde, methylaniline, and p-chloro-methylaniline. ment of an allyl group in a dyad system, re- Cleavage of VI11 by hydrogenation to benzyl sembling the Claisen rearrangement. If this alcohol and inethylaniline verified this structure. interpretation is correct, the only function of the CHs CHI I 1 sodium hydroxide present in the reaction mixture C6Hs-Y .-c0 +CsHs-N--OCHGHa is to convert the amine oxide from a salt into the free base. Another possible mechanism is an CH2Ce” _____f
(1) Musenheirner Bcr , 6a, 1667 (1919) (1) Meiwnheimer
