Zhu, Zixi; Boger, Dale L. published the artcile< N1/N4 1,4-Cycloaddition of 1,2,4,5-Tetrazines with Enamines Promoted by the Lewis Acid ZnCl2>, Quality Control of 112-63-0, the main research area is tetrahydrobenzotriazine preparation; tetrazine enamine zinc mediated regioselective cycloaddition.
The second example of selective N1/N4 1,4-cycloaddition (vs C3/C6 1,4-cycloaddition) of 1,2,4,5-tetrazines with preformed or in-situ generated enamines promoted by the Lewis acid ZnCl2 and with an expanded scope was described. The reaction constituted a formal [4+2] cycloaddition across two nitrogen atoms (N1/N4 vs C3/C6) of a 1,2,4,5-tetrazine followed by retro [4+2] cycloaddition loss of a nitrile and aromatization to provide 1,2,4-triazines. Optimization of reaction parameters, simplification of its implementation through in-situ enamine generation from ketones, definition of the enamine reaction scope for 3,6-bis(thiomethyl)-1,2,4,5-tetrazine, exploration of the 1,2,4,5-tetrazine scope, and representative applications of the product 1,2,4-triazines were detailed. The work established and further extended a powerful method for efficient one-step regioselective synthesis of 1,2,4-triazines under mild reaction conditions directly now from easily accessible ketones. It extended the substrate scope of a solvent (hexafluoroisopropanol) hydrogen bonding-promoted reaction that recently reported with aryl-conjugated enamines, permitting the use of simple ketone-derived enamines and expanding the generality of the remarkable reaction. The reaction was regioselective with respect to the site of reaction with unsym. ketones and provided exclusively a single 1,2,4-triazine regioisomer consistent with previously established stepwise mechanism of formal N1/N4 1,4-cycloaddition, overcoming the challenges observed in conventional approaches to 1,2,4-triazines.
Journal of Organic Chemistry published new progress about Cycloaddition reaction catalysts (regioselective). 112-63-0 belongs to class esters-buliding-blocks, and the molecular formula is C19H34O2, Quality Control of 112-63-0.
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