ethyl 3,4-dimethylpent-2-enoate

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 3,4-Dimethyl-2-pentenoic acid (XI, 4.1 g) was heated to a gentle boil with thionyl chloride (50 g) in benzene (50 mL) until the generation of hydrochloric acid gas ceased. Removal of the excess thionyl chloride and benzene by evaporation in vacuo followed by a distillation of the reaction product gave pure 3,4-dimethyl-2-pentenoylchloride (IX, 64° C. (9.5 mm)). Removal of the excess thionyl chloride and benzene by evaporation in vacuo followed by a distillation of the reaction product

Conditions: temp:80.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of aqueous potassium hydroxide solution (0.5 N, 92 mL) and ethyl 3,4-dimethyl-2-pentenoate (XI, 5.5 g) was stirred at 80° C. for 17 hours until the oily supernatent layer disappeared. The reaction mixture was cooled, acidified with aqueous sulfuric acid, (0.5 N, ca. 100 mL), and extracted with ether. The ethereal layer was washed with water, dried over anhydrous magnesium sulfate, filtered, and evaporated under reduced pressure to afford 3,4-dimethyl-2-pentenoic acid as a yellow liquid (X, 4.1 g, 91%). The reaction mixture was cooled extracted with ether The ethereal layer was washed with water dried over anhydrous magnesium sulfate filtered evaporated under reduced pressure

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 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. was added dropwise under nitrogen in an ice bath (ca. 0° C.) the mixture stirred at ambient temperature for three hours The mixture was cooled extracted with ether The ethereal extract was dried over anhydrous magnesium sulfate filtered evaporated in vacuo

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The 3,4-dimethyl-2-pentenoyl chloride (IX) utilized in the procedures of the present invention may be readily prepared from 3-methyl-2-butanone (XII) utilizing the Wittig reaction. In this procedure triethylphosphonoacetate is added to a suspension of sodium hydride in diglyme in an inert atmosphere at a temperature of between -10° C. and 5° C., suitably about 0° C. The mixture is stirred, suitably for about half an hour, to ensure formation of the Wittig reagent and the ketone (XII) added slowly thereto. There is utilized approximately 100% molar excess of the triethylphosphonoacetate with respect to the ketone (XII). The reaction is completed by allowing the reaction mixture to equilibrate with room temperature after completion of the addition, and remaining at ambient temperature from between 2 to 5 hours. The mixture is then recooled and carefully quenched with a large excess of water and the reaction product extracted therefrom with a reaction inert water insoluble organic solvent, suitably ether and the thus produced ethyl 3,4-dimethyl-2-pentenoate (XI) isolated from the ethereal extract in the usual manner. the Wittig reaction to equilibrate with room temperature after completion of the addition remaining at ambient temperature from between 2 to 5 hours carefully quenched with a large excess of water the reaction product extracted

Conditions: temp:0.00; pressure:0.00; stir: