Synthesis of [1,4]Oxazino[3,2- e ][1,2,4]triazines by One-Pot Cascade Regioselective Substitutions of 3,5,6-Trichloro-1,2,4-triazine with Amino Alcohols

A regioselective, one-pot cascade substitution protocol for 3,5,6-trichloro-1,2,4-triazine with diverse amino alcohols was developed and optimized. This approach enables the efficient synthesis of a broad array of [1,4]oxazino[3,2-e][1,2,4]triazines. Significantly, the methodology employs readily available chemicals and has short reaction times. Furthermore, the scope of postsynthetic modifications was explored through high-throughput experimentation (HTE), and a proof-of-concept one-pot, three-step cascade sequence was demonstrated to afford a fully functionalized [1,2,4]triazine core.