Novel syntheses of camptothecin alkaloids. Part I. Intramolecular [4+2] cycloadditions of N-arylimidates and 4H-3,1-benzoxazin-4-ones as 2-aza-1,3-dienes was written by Fortunak, Joseph M. D.;Mastrocola, Antonietta R.;Mellinger, Mark;Sisti, Nicolas J.;Wood, Jeffery L.;Zhuang, Zhi-Ping. And the article was included in Tetrahedron Letters in 1996.Safety of Ethyl 5-cyano-4-methyl-6-oxo-1,6-dihydropyridine-2-carboxylate The following contents are mentioned in the article:
Intramol. [4+2] cycloadditions of both N-arylimidates and (4H)-3,1-benzoxazin-4-ones acting as 2-aza-1,3-dienes were described. Reaction with unactivated alkynes lead to pyrrolo[3,4-b]quinolines containing the ABC ring system of camptothecin. E.g., 10-methoxycamptothecin precursor I was prepared by intramol. [4+2] cycloaddition of a 4:1 isomeric mixture of O-methylimidate II (R = 4-MeOC6H4), which had been prepared by Me3OBF4 O-methylation of the corresponding N-(4-methoxyphenyl)-amide, followed by elimination of methanol. This study involved multiple reactions and reactants, such as Ethyl 5-cyano-4-methyl-6-oxo-1,6-dihydropyridine-2-carboxylate (cas: 58610-61-0Safety of Ethyl 5-cyano-4-methyl-6-oxo-1,6-dihydropyridine-2-carboxylate).
Ethyl 5-cyano-4-methyl-6-oxo-1,6-dihydropyridine-2-carboxylate (cas: 58610-61-0) belongs to pyridine derivatives. Pyridine has a dipole moment and a weaker resonant stabilization than benzene (resonance energy 117 kJè·¯molé? in pyridine vs. 150 kJè·¯molé? in benzene). Several pyridine derivatives play important roles in biological systems. While its biosynthesis is not fully understood, nicotinic acid (vitamin B3) occurs in some bacteria, fungi, and mammals.Safety of Ethyl 5-cyano-4-methyl-6-oxo-1,6-dihydropyridine-2-carboxylate