Dicyclohexylcarbodiimide → Benzyl 6-hydroxy-6-(4,4-dimethyl-2,6-dioxocyclohexylidene)-hexanoate

Participants

Reaction Steps

To a stirred solution of mono-benzyl adipate (2.36g, 10 mmol) in dry CH2Cl2 (50 ml) was added 5,5-dimethyl-1,3-cyclohexanedione (1.4 g, 10 mmol), N,N′-dicyclohexylcarbodiimide (2.1 g, 10.1 mmol) and 4-dimethylaminopyridine (1.22 g, 10 mmol). The resulting solution was allowed to stir at room temperature for 18 h. The solution was cooled and filtered to remove the precipitated N,N′-dicyclohexylurea. The filtrate was evaporated and the residue redissolved in EtOAc (50 ml) and washed with 1 M KHSO4. The organic extract was washed with brine (92×10 ml), dried (MgSO4) and evaporated to yield a white/yellow amorphous powder. Flash silica chromatography (EtOAc/hexane 1:2 v/v) afforded benzyl 6-hydroxy-6-(4,4-dimethyl-2,6-dioxocyclohexylidene)-hexanoate (3.00 g, 84%) as a white crystalline solid. 1H NMR (CDCl3) δ 18.10 (s, 1H, OH), 7.30 (s, 5H, 5Ar—H), 5.06 (s, 2H, CH2Ar), 3.00 (t, 2H, CH2), 2.47 (s, 2H, Dde CH2), 2.35 (t, 2H, CH2CO2), 2.29 (s, 2H, Dde CH2), 1.65 (m, 4H, 2 CH2), 1.01 (s, 6H, 2 CH3); FAB MS C21H26O5 (358.18) m/z (%) 359 [M+H]+ (100), 267 (40); HRMS (FAB) Found: m/z 359.1858 Calcd for C21H27O5: (M+H), 359.1850.

Provenance & Evidence