Pyrimidines diazo-coupling

TV-protected ort/20-anilineboronic acid was used by Matyus and coworkers to introduce an annelating cinnoline ring onto pyrimidine derivatives. The connection of the phenyl and pyrimidine moieties by Suzuki coupling was followed by the establishment of the carbon-nitrogen bond through a diazo-coupling (4.5.),6... 

Mannich reactions and diazo coupling proceed readily in pyrimidines provided activating groups are present in each of the 2-, 4- and 6-positions. 

With aryldiazonium chlorides the pyrido[l,2-a]pyrimidines (63 R = H) yielded the 3-arylazo derivatives.253 The 3-methyl derivative of 63 (R = H) was also subjected to diazo coupling, but the product, a 3,3-disubstituted pyrido[l,2-a]pyrimidine, underwent immediate transformation involving hydrolysis of the C-4—N-5 bond253 (see also Section III.C,4). 

The carbocyclic nucleoside analogs 342-344 were prepared by diazo coupling of (lJ mJ-S-pyrimidylaminomethyl-l -trimethylcyclopentyl-methanol (339) with 4-chlorobenzenediazonium chloride to give 340, which upon reduction gave the triamine 341. Ring closure of 341 with nitrous acid gave (17 ,c/s)-3-[(5-amino-7-chloro-3//-l,2,3-triazolo[4,5-d]pyrimidin-3-yl)-... 

Acylation and metallation studies on monomers, dimers, trimers, and tetramers containing linked thiophen, pyridine, pyrimidine, furan, benzofuran, benzothiophen, and indole moieties have been published/ Deuteriation, halogenation, and diazo-coupling reactions of 2-oxo- and 2-thioxo-l,2-dihy-dropyrimidinium salts have been studied and compared with results for 2,2-dialkyl-1,2-dihydropyrimidinium and 2,3-dihydro-1,4-diazepinium salts in order to demonstrate the effect of an adjacent 0x0- or thioxo-group on the properties of a 1,5-diazopentadienium system/ Vilsmeier formylation of, and tautomerism in, 2-hydroxypyrazolo[5,l-h]quinazolone and l-phenylpyrazolo[5,l-A]-quinazoline-2,9-dione have been studied/ The pyrazolo[3,4-c]pyrazole (71) has been methylated and acetylated, the major products being (72)/ ... 

Heterocyclic coupling components have, in a similar manner as heterocyclic diazo components (sect. 2.1.4), recently become very important and are used in large scale industrial production of dyestuffs and chemicals. A recent review deals with the industrial um of pyrazolones 75, iminopyrazoles 76, pyridones 77, amino-pyrimidines 78, aminopyridines 79, hydrochinolines 80 and aminothiazoles 81 as coupling components. 

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