Diketene → (R)-1-trichloromethyl-3-methyl-2-butenyl acetoacetate

Participants

Reaction Steps

A mixture of (2R)-1,1,1-trichloro-4-methyl-3-penten-2-ol (1.50 g., 7.35 mmole) from Example IA.1.(a) and a trace of sodium acetate was treated under nitrogen at 100° with freshly distilled diketene (0.70 g, 8.36 mmole) added dropwise over 1 hr. After stirring and heating an additional hour at 80°-83°, the cooled reaction mixture was diluted with 3 ml of CH2Cl2 and chromatographed on 8 (20×20 cm) preparative tlc plates, developed in CH2Cl2. Isolation and extraction afforded (1R)-3-methyl-1-trichloromethyl-2-butenyl acetoacetate (1.80 g, 85% isolated yield) as a pale yellow oil; [α]D31 =+21.1° (hexane).

Provenance & Evidence