Water → Ethyl 3,4-dimethyl-2-pentenoate

Participants

Reaction Steps

To a suspension of sodium hydride (2.6 g) in diglyme (10 mL) triethylphosphonoacetate (24 g, 107 mmol) was added dropwise under nitrogen in an ice bath (ca. 0° C.). The mixture was stirred for 30 min. and then 3-methyl-2-butanone (XII, 4.3 g, 50 mmol) was added dropwise and the mixture stirred at ambient temperature for three hours. The mixture was cooled, diluted cautiously with a large excess amount of water, and extracted with ether. The ethereal extract was dried over anhydrous magnesium sulfate, filtered and evaporated in vacuo to yield ethyl 3,4-dimethyl-2-pentenoate (XI, 7.1 g, 91%): NMR (Jeol C 60 HL, CDCl3) δ1.08 [6H, d, J=7 Hz, (CH3)2CH], 1.30 (3H, t, J=7 Hz, CH3CH2O), 2.15 (3H, d, J=1.5 Hz, CH3C=), 4.15 (2H, q, J=7 Hz, CH 3 CH2O), 5.68 (1H, br.s, CH=C); IR (neat) 1705 (C=O), 1640 (C=C), 1385 and 1365 [(CH3)2C] cm-1 ; GLC (2% OV-17, Chrom W 80/100, 2 mm×200 cm, 60° C., N2 30 cc/m) retention time, 9 min.

Provenance & Evidence