2-Amino-3-formylpyridine

The involvement of an amidine group as C-N partner for interchange with the C(2)-N part of the pyridine ring has been observed during base treatment of the 3-formamidopyridinium salt 2-amino-3-formylpyridine is formed in a reasonable yield (Scheme IV.50) [79ZN(B)1019].The reaction follows the same pathway as described in Scheme IV.49. 

There are numerous examples of the use of 2-amino-3-formylpyridine 203 in the synthesis of substituted 1,8-naphthyridines and their fused analogs (1986JIC345, 1986JIC443, 1989CCC1716, 1989IJC362, 1994TL1995). 

Quinazolin-2-one was obtained quantitatively by fusing 2-aminobenzaldehyde with urea (10 min at 150°C).76,91 Similarly, 2-amino-3-formylpyridine and urea (15 min at 160°C) gave an excellent yield of pyrido[2,3-d]pyrimidin-2-one (see 3).92 Finally, as an example from jt-excessive chemistry, 2-amino-indole-3-aldehyde was converted to its 2-benzyloxycarbonyl derivative, which benzylamine quantitatively converted to 3-benzyl-9f/-pyrimidino-[4,5- >]indol-2-one (87)93... 

Perfluoroalkyl [1, 8]-naphtiridine (318) with herbicidal effect was synthesized by reaction of 2-amino-3-formylpyridine (315), 1,3-dicarbonyl componnd 316 and 1,3-cyclohexanedione (317) [187] (Scheme 90). 

Several other organic and inorganic reaction intermediates have been studied using NMR methods. Trahanovsky et al. [12] reported a series of experiments in which they studied unstable molecules, such as benzocyclobutadiene, using flow NMR. Tan and Cocivera [13, 14] studied the reaction of 4-formylpyridine with amino acids, imidazole and D,L-alanylglycine using stopped-flow proton NMR. 

To further enlarge the scope of this synthetic approach, they simultaneously combined three types of reversible interactions, 3-chloro-4-formylpyridine 14 and 3-amino-phenylboronic acid 13 through a condensation as well as metal-ligand interactions using ReBr(CO)5 closing the cycle [13]. The presence of metal could assist the macrocycle formation, in which 12 building blocks are... 

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