Organic Reactions Volume 4 - Sciencemadness Dot Org

DIENE SYNTHESIS I 35
Numerous other a- and /3-naphthyl and 9-phenanthryl derivatives
react with maleic anhydride in a similar manner (see Table V), The
following, however, fail to react: 66 - 265 ' 266 l~a-naphthyl-l-cyclohexene
(though l-/?-naphthyl-l-cyclohexene reacts); a-9-phenanthrylstilbene;
9-cyclohexenylphenanthrene (though 9-cyclopentenylphenanthrene reacts);
l / -(9-phenanthryl)-l / -phenylethylene [though l'-(9-phenanthryl)-
2'~phenylethylene reacts]; and 9,9'~biphenanthryl.
There appears to be some correlation between the absorption spectrum
of a phenanthrene derivative and its ability to undergo the Diels-Alder
reaction. Thus, 9-cyclopentenylphenanthrene exhibits the washed-out
spectrum associated with conjugated resonance states, and it also reacts
with maleic anhydride. 9-Cyclohexenylphenanthrene and 9,9'~biphenan~
thryl, on the other hand, fail to react, and their absorption spectra are
close to those of their components. 267
The reaction of maleic anhydride with aromatic-aliphatic dienes has
been employed for the synthesis of compounds containing an angular
methyl gr0up. 128a ' 264 ' 268 ' 269
Reaction of Maleic Anhydride with Heterocyclic Compounds. The
furan nucleus undergoes the Diels-Alder reaction with extraordinary
facility to yield an adduct which has an oxygen bridge (LXXXVII).
1:
H^=CH
> + If > > Cof \
LXXXVH
This type of adduct gives the corresponding phthalic anhydride when
heated with hydrogen bromide in acetic acid. 270 Furfuryl derivatives,
270 ' 271 as well m substituted furans carrying alkyl groups 121 ' 272 " 276
or halogen, 270 yield normal adducts, but furans with a carbethoxyl,
cyano, or nitro group directly attached to the ring have not yielded
addition products. 270 Although /5-hydroxyfuran gives an adduct, a-
265 Bergmann and Bergmann, /, Am. Chem. Soc, 59, 1443 (1937).
266 Bergmann and Bergmann, J*. Am. Chem, Soc, 62, 1699 (1940).
267 Calvin, /. Org. Chem., 4, 256 (1939).
268 Meggy and Robinson, Nature, 140, 282 (1937),
269 Koebner and Robinson, «/, Chem. Socn 1941, 566,
270 Van Campen and Johnson, J. Am. Chem. /Soc, 55, 430 (1933).
271 Diels, Alder, Nienburg, and Schmalbeek, Awn., 490? 243 (1931),
272 Butz, /. Am. Chem. Soc, 57, 1314 (1935).
273 Alder and Backendorf, Ann., 535, 101 (1938).
274 Woodward, J. Am. Chem. Soc., 62, 1478 (1940).
275 Diels and Olsen, J. prakt. Chem., (2) 156, 285 (1940).
278 Paul, Bull soc. chim. France, [5] 10, 163 (1943) [C. A., 38, 3978 (1944)].