Synthesis of 3-amino-2-pyridinecarboxaldehyde thiosemicarbazone (3-AP) was written by Niu, Chuansheng;Li, Jun;Doyle, Terrence W.;Chen, Shu-Hui. And the article was included in Tetrahedron in 1998.Reference of 209798-48-1 This article mentions the following:
Palladium-catalyzed cross-coupling of methylboronic acid with 2-chloro-3-nitropyridine produced 2-methyl-3-nitropyridine in one step in high yield. Oxidation of the latter with selenium dioxide gave an aldehyde. Alternatively, condensation of 2-methyl-3-nitropyridine with DMFDMA followed by oxidation gave 3-nitro-2-pyridinecarboxaldehyde in a two step higher yielding conversion. Subsequent direct coupling of 3-nitro-2-pyridinecarboxaldehyde with thiosemicarbazide followed by reduction of the nitro group using stannous chloride or sodium sulfide provided 3-AP. Reduction with sodium hydrosulfite gave 3-HAP. Finally a route which avoids the reduction of a nitro function was devised. Thus direct coupling of styrene with 2-chloro-3-aminopyridine under Heck reaction conditions gave a product which was converted to an aldehyde and converted to 3-AP with in situ deblocking of the BOC functionality. In the experiment, the researchers used many compounds, for example, (2-Chloro-pyridin-3-yl)-carbamic acid tert-butyl ester (cas: 209798-48-1Reference of 209798-48-1).
(2-Chloro-pyridin-3-yl)-carbamic acid tert-butyl ester (cas: 209798-48-1) belongs to pyridine derivatives. Pyridine has a conjugated system of six π electrons that are delocalized over the ring. The molecule is planar and, thus, follows the Hückel criteria for aromatic systems. Pyridine, its benzo and pyridine-based compounds play diverse roles in organic chemistry. Pyridine-based materials are valued for their optical and physical properties as well as their medical potential. Reference of 209798-48-1