Organic Reactions, Volume 2

RELATION OF BOND STRUCTURE TO REARRANGEMENT 13
Although the effect of ring Bubstituents; other than carboxyl and
aldehyde groups, upon the rearrangement is usually small, provided that
one or more unsubstituted ortho or para positions are available, poor
results have been reported with the following ethers of substituted
phenols;,it is probable that further study will disclose satisfactory
reaction conditions for at least some of these rearrangements. Allyl 2allyl-4-methylphenyl
ether' and the allyl ether of allyl-m^cresol give
poor reactions, probably because of polymerization.* Allyl 4-nitrophenyl
ether rearranges in 30 to 40% yield on refluxing in paraffin oil at
230°; the 2-nitro compound gives a 73% yield at 180°. f Allyl 2-(hydroxymethyl)-phenyl
ether yields formaldehyde and decomposition
products when heated,X but it is reported 48 that allyl 2-methoxy-4-
(7-hydroxypropyl)-phenyl ether rearranges (in unspecified yield), so
that a hydroxyl group in a side chain does not necessarily preclude rearrangement.
Relation of Bond Structure to Rearrangement. Numerous examples
have been found, in the allyloxy derivatives of polycyclic aromatic compounds
in particular, where rearrangement does not take place although
it would be expected if the aromatic nucleus could react in all of the possible
Kekule" bond structures. From the introductory discussion, it is
clear that the reaction requires the ether oxygen to be attached to a
double bond and that after rearrangement the allyl group is attached to
the same double bond. The failure of l-allyl-2-allyloxynaphthalene
(XLIV) to rearrange even after long heating x is explained by assuming
C3H6 C3H5 CSHB
C3H6
XLIV XLV XLVI
that the naphthalene nucleus cannot react in the unsymmetrical form
(XLV), with a double bond in the 2,3-position. While 2,6-diallyloxynaphthalene
49 rearranges smoothly in 85% yield, l,5-diallyl-2,6-diallyloxynaphthalene
(XLVI) does not rearrange in five minutes at 200° and,
on longer heating, decomposes without forming any alkali-soluble material.
This supports the conclusion that naphthalene does not undergo
reactions which would require double bonds in the 2,3- and 6,7-positions.
* See pp. 45 and 58 of the article cited in reference 44.
t See pp. 40 and 59 of the article cited in reference 44.
t See p. 106 of the article cited in reference 44.
48
Kawai, Nakamura, and Sugiyama, Proc. Imp. Acad. Tokyo, 15, 45 (1939) [C. A., 33,
5394 (1939)].
49
Fieser and Lothrop, J. Am. Chem. Soc., 57, 1459 (1935).,