1,8-Diazabicyclo(5.4.0)undec-7-ene → 2-Benzyloxycarbonylamino-5,5-dimethyl-hept-2,6-dienoic acid methyl ester

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Reaction Conditions

Reaction Steps

N-(Benzyloxycarbonyl)-α-phosphonoglycine trimethyl ester (34.3 g, 103 mmol, 1.0 equiv) was dissolved in dry THF (250 mL) and the solution was cooled to 0° C. 3,3-Dimethyl-pent-4-en-al (11.6 g, 103 mmol, 1.0 equiv) and DBU (15.5 mL, 103 mmol, 1.0 equiv) were added and the reaction mixture was stirred for 16 h. The solution was diluted with 500 mL of CH2Cl2 and washed with 1×150 mL water, and 1×150 mL brine. The organic layer was dried over Na2SO4, decanted and concentrated in vacuo to provide 2-benzyloxycarbonylamino-5,5-dimethyl-hept-2,6-dienoic acid methyl ester as a thick oil (31 g, 95% crude). The enamide is purified by flash chromatography on silica using hexanes/EtOAc as mobile phase to yield 2-benzyloxyearbonylamino-5,5-dimethyl-hept-2,6-dienoic acid methyl ester as a thick oil that solidifies on standing.

Provenance & Evidence