2',6'-exo-spiro[cyclopentane-1,5'-[4,10]dioxatricyclo[5.2.1.02,6]dec-8'-en-3'-one]

carbon monoxide

1-乙炔基环戊醇

1-vinyl-1-cyclopentylacrylate

hydroxy-2 oxa-1 spiro(4,4) nonene-3