tert-butyl 3-methoxycarbonyl-1-oxa-9-azaspiro[5.5]undec-3-ene-9-carboxylate
tert-butyl 4-{[2-(methoxycarbonyl)prop-2-en-1-yl]oxy}-4-(prop-2-en-1-yl)piperidine-1-carboxylate
1-(t-butoxycarbonyl)-4-(prop-2-enyl)-4-hydroxypiperidine
9-tert-butyl 3-methyl 1-oxa-9-azaspiro[5.5]undecane-3,9-dicarboxylate
trifluoroacetic acid