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Titlea review of the literature abstracted between July 1980 and June 1981
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Page 206

184 Heterocyclic Chemistry

(295) from 2,7-dibromo-1,6-methano[ 101annulene and toluene-3,4-dithiol has
been described.334

M e G C + f j + s B - s ’ Me


syn-Diselenadithiafulvalene (296) and the anti-isomer have been obtained as
an inseparable Reductive coupling of+the diselenoleselone (297;
X = Se)336 or the immonium salt (297; X = Me2N)337 yields the tetraselena-
fulvalene (298).

Pyrazoles.-Formation. l-Phenyl-2-(phenylazo)acetylene reacts with the
enamine PhSCH=CHNMe2 to yield the pyrazole (300) via the intermediate
(299).338 Thermolysis of the azine (F3C)2C=N-N=C(CF3)2 in the presence of
phenylacetylene and tetrahydrofuran results in compound (301).399 The
diazomethane derivative Me,As(Me,Sn)CN, adds to dimethyl acetylene-
dicarboxylate to give the pyrazole (302) by a ‘metallotropic’ shift of the tri-
methylstannyl group from carbon to Perfluoro-2-methylpent-2-ene
and 1,l-dimethylhydrazine form the zwitterion (303).341


The formation of a 7.4: 1 mixture of 3- and 4-methylpyrazolines in the
cycloaddition of diazomethane to propene is claimed342 to support a diradical

334 R. Neidlein and H. Zeiner, Angew. Chem., Znt. Ed. Engl., 1980, 19, 204.
335 M. V. Lakshmikantham and M. P. Cava, J. Org. Chem., 1980,45, 2632.
336 L. Y. Chiang, T. 0. Poehler, A. N. Bloch, and D. 0. Cowan, J. Chem. SOC., Chem. Commun.,

337 F. Wudl and D. Nalewajek, J. Chem. SOC., Chem. Commun., 1980, 866.
338 T. Agawa, M. Ishikawa, M. Komatsu, and Y. Ohshiro, Chem. Lett., 1980,335.
339 K . Burger and C. Zettl, Chem.-Ztg., 1980, 104, 71.
14n M. Birkhahn, R. Hohlfeld, W. Massa, R. Schmidt, and J. Lorberth, J. Orgunomet. Chem., 1980,

341 I. Ikeda, T. Tsukamoto, and N. Okahara, Chem. Lett., 1980,583.
342 R. A. Firestone, Tetrahedron Lett., 1980, 21, 2209.



Page 207

Five-Membered Rings: Other systems 185

mechanism for the reaction. The diazo-alkenes (304; R = Me or Ph) undergo
a stereospecific intramolecular cycloaddition to yield the aziridinopyrazolines
(305);343 o-allylphenyldiazomethane forms compound (306) in this type of

Me0,C AsMe,

Me02C)\N N N
I Me,



Ph/? d H R * P h d N’ H

H &
Rearrangement of the toluene-p-sulphonylhydrazones of 1 -acyl-oxirans (307 ;

R = Et or Ph) yields the hydroxy-pyrazolines (308) as mixtures of
Treatment of acetophenone phenylhydrazone with lithium di-isopropylamide
produces the dilithio-derivative LiCH2PhC=N-NPhLi, which reacts with
diethyl carbonate to furnish the pyrazolinone (309).346 The 3H-pyrazole N-oxide
(310) is formed from the dioxime HON=CPhCMe2CPh=NOH under the
conditions of the Beckmann rear~angernent.~~’


R M e F N R N oc? N N
(307) Ph



Reactions of Pyruzoles. Nitration of 4,5-dibromo-1,3-dimethylpyrazole (31 1 ;
R’ = RZ = Br) gives a mixture of the bromonitropyrazole (3 11 ; R’ = Br, R2 =
NO,) and the debrominated compound (311; R’ = H, R2 = N02).348 Oxidative
coupling of the dilithio-derivative (3 12) of p-phenylenedipyrazole leads to com-
pound (313), in which the benzene rings are rigidly held face-to-face, causing
an upfield shift of the aromatic The chromium-nitrogen-platinum

343 A. Padwa and A. Rodriguez, Tetrahedron Lett., 1981, 22, 187; T. Miyashi, Y. Fujii, Y. Nishizawa,
and T. Mukai, J. Am. Chem. SOC., 1981,103,725.

344 A. Padwa and H. Ku, J. Org. Chem., 1980,453756.
34s W. H. Pirkle and D. J . Hoover, J. Org. Chem., 1980, 45, 3407.
346 J. D. Wilson, T. D. Fulmer, L. P. Dasher, and C. F. Beam, J. Heterocycl. Chem., 1980,17, 389.
347 H. Gnichtel and U. Bohringer, Chem. Ber., 1980,113, 1507.
348 M. A. Andreeva, M. I. Bolotov, Sh. G. Isaev, V. P. Perevalov, and B. I. Stepanov, Khim. Geterotsikl.

349 H. Lexy and T. Kauffmann, Chern. Ber., 1980,113,2749,2755.
Soedin., 1980, 1561.

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