Synthesis of new polyaza heterocycles. Part 42: Diazines

Transition metals in organic synthesis: Highlights for the year 2005

“…A variety of heterocyclic tin derivatives, such as 4-fluoro-5-pyrazolyl [11], 2-indolyl [12], 2-pyridyl [13], 6-chloro-2-pyrazinyl [14], 2-oxazolyl [15] and 3-pyrazinyl, 2-pyrimidinyl, and 2-pyridazinyl [16] stannanes were used in Stille-type couplings with aromatic halides. A ferrocenyl tin reagent was coupled with bromopyridine N-oxides [17].…”

Synthesis and antiprotozoal activity of dicationic 2,6-diphenylpyrazines and aza-analogues

“…1) and their aza-analogues (e.g. 6 ), which showed significant DNA minor groove binding affinity and low nanomolar antiprotozoal activity against T. b. r. and P. f. 14–16 The in vivo efficacy for three of those aza-analogues in the T. b. r. STIB900 acute mouse model is much superior to that of furamidine, and comparable to the azafuramidines. Unfortunately, the di-amidoximes and di- O -methylamidoxime prodrugs of the terphenyl dicationic analogues showed poor bioconversion and were not effective on oral administration.…”

Metalated heterocycles in organic synthesis: Recent applications

“…389 This type of heteroaryl stannanes have been also obtained by halogen-lithium-tin exchange, and dedicated to Stille reactions in the synthesis of cyclin-dependant kinase inhibitors, 390 and also from 2-chloropyrazines by reaction with (tri-n-butylstannyl)lithium in the synthesis of polynuclear polyaza heterocycles. 391 In addition, 2-stannylpurines, generated by direct 2-lithiation followed by reaction with a trialkylstannyl chloride, have also been used in Stille reactions, for instance, in the synthesis of adenosine derivatives. 392 2-Stannylated purines have been also employed in the ipso-iodination reaction, thus creating a template for further functionalization, 393 as illustrates Scheme 63 for the iodination of the stannyl purine ring of nucleoside derivative 210 affording the iodinated purine 211.…”