By Gould R.F. (ed.)
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Extra info for Addition and Condensation Polymerization Processes
The geometry of the coordination complex (113) makes addition of the amide ion at C-2 attractive. Conditions needed to generate a diamino derivative are typically harsher than those required for monoamination. A Japanese patent cites the preparation of 2,6-diamino-4-propylpyridine (I 15) from 4-propylpyridine (114) with excess sodium amide in Tetralin at 145-195°C (Scheme 45) (80JAP(K)76861). n-Pr n-Pr NH, SCHEME 46 Sec. B] ADVANCES IN THE CHICHIBABIN REACTION 41 Other pyridine derivatives have been aminated with alkali metal amides.
This argument is weakened by the lack of a kinetic isotope effect in the Chichibabin amination (65CJC725). Alternatively, the amide ion may be attracted to the 2-position by an ion-dipole interaction with the 3-substituent in the addition step. For a substrate like 3-dimethylaminopyridine (1lo), this is a very significant interaction (113), leading exclusively to the 2-amino product (Scheme 44) (73CHE1119). Pyridine rings containing electron-donating substituents are deactivated toward the Chichibabin reaction relative to pyridine.
Amination of 5-bromo- 1,7-naphthyridine with potassium amide in liquid ammonia gave a small yield of a normal Chichibabin product, 8-amino-5bromo- 1,7-naphthyridine, along with tele-aminated products 8-amino- and 2amino-l,7-naphthyridine. 5-Chloro-l,7-naphthyridine(202) gave a low yield of 8-amino-5-chloro- 1,7-naphthyridine (203)and other unidentified products (Scheme 71) (78JHC731). 56 CHARLES K . McGILL AND ANGELA RAPPA CI [Sec. E CI NaNH, k RI SCHEME 72 E. (82CHE1221). Criteria for successful amination require that the imidazole ring be condensed with an aromatic system at the 4and 5-positions, and that the pyrrole nitrogen be substituted (Scheme 72) (73CHE88).
Addition and Condensation Polymerization Processes by Gould R.F. (ed.)