Halogeno-1,7-naphthyridines positional activation

The literature contains some basic information on the preparation and reactions of halogeno-2,7-naphthyridines. In this system, halogeno substituents are active at the 1-, 3-, 6-, and 8-positions but inactive at the 4- and 5-positions. The effect of fluoro substituents on the ultraviolet spectra of 2,7-naphthyridines has been investigated.1313 Reviews have appeared.1266,1363... 

In contrast to the situation in halogeno-1,5-naphthyridines (see Chapter 3), a halogeno substituent on 1,6-naphthyridine will be activated at the 2-, 4-, 5-, and 7-positions and much less so at the 3- and 8-positions. 

Halogeno-2,6-naphthyridines have good (but largely unused) potential as intermediates for metatheses, especially when the halogeno substituent occupies the activated 2-, 3-, 5-, or 7-position. 

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