propyl (4S)-4-ethyl-3,4-dihydroxy-8-methoxy-1,3-dihydropyrano[3,4-c]pyridine-6-carboxylate

propyl (S)-4-ethyl-3,4,7,8-tetrahydro-4-hydroxy-3,8-dioxo-1H-pyrano[3,4-c] pyridine-6-carboxylate

propyl (S)-4-ethyl-3,4-dihydro-4-hydroxy-8-methoxy-3-oxo-1H-pyrano[3,4-c]pyridine-6-carboxylate

tert-butyl (4S)-4-ethyl-4,6-dihydroxy-3,10-dioxo-1,8-dihydropyrano[3,4-f]indolizine-7-carboxylate

2'-amino-5'-hydroxypropiophenone