三氯乙醛

tert-butyl 2,2-dihydroxy-3-oxopent-4-enoate

tert-butyl 5-chloro-3-oxopentanoate

tert-butyl 5-chloro-2-(((p-nitrophenyl)sulfonyl)oxy)-3-oxopentanoate

t-Butyl 5-Chloro-3-oxo-2-(triphenylphosphoranylidene)-pentanoate