1.2.4- Triazolo pyrimidines lithiation

As with their monocyclic analogs, lithiated derivatives of bicyclic di-azines can be prepared by halogen-metal exchange at low temperature, and examples include the 6-lithiopurine 130 (79JOC4612), and the 5-and 7-lithio-3//-l,2,3-triazolo[4,5-(f pyrimidines 131 and 132 (91CPB2793, 91CPB3037). 

There are no reports since 1996, although lithiation of [l,2,3]triazolo[4,5- / pyrimidine at the 7-position followed by reaction with electrophiles was briefly covered in the review by Knowles <1996CHEC-II(7)489>. 

In an ancillary study, the lithiation of triazolo[l,5-c]pyrimidine 522 under a variety of conditions proved to be unsuccessful (Scheme 159) [82 JCS(P 1)967]. 

Chloroperoxidase catalysis by, 58, 302 in chlorination of pyrazoles, 57, 337 Chlorophyll, thioaldehyde synthetic intermediate to, 55, 3 Chlorosulfonyl isocyanate, reaction with 2-arylhydrazono-3-oxobutanoate, 59, 148 Chromatography, of [l,2,4]triazolo[l,5-a]-pyrimidines, 57, 106 Chrom-3-enes, see 2//-l-Benzopyrans Chromium tricarbonyl complexes of 3,5-diphenyl-l-(alkyl- or oxido-)-thiabenzenes, 59, 206, 227 indoles, lithiation of, 56, 181, 184 of pyridine, 58, 160 pyridines, lithiation of, 56, 230, 239 of 2f/-thiopyrans, 59, 227 Chromones, see l-Benzopyran-4-ones Cinnamonitrile, a-cyano-, condensations with thio-, seleno-amides, 59, 184, 186 Cinnoline, nitration, MO calculation, 59, 302... 

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