2,2-Dimethyl-1-(6-((trimethylsilyl)ethynyl)-2,3-di hydro-1H-pyrido[2,3-b][1,4]oxazin-1-yl)propan-1-on2,2-Dimethyl-1-(6-((trimethylsilyl)ethynyl)-2,3-dihydro-1H-pyrido[2,3-b][1,4]oxazin-1-yl)propan-1-one2,2-Dimethyl-1-(6-((trimethylsilyl)ethynyl)-2,3-dihydro-1H-pyrido[2,3-b][1,4]oxazin-1-yl)propan-1-one