Acetic Acid → HCID 129281815, compound

Participants

Reaction Conditions

Reaction Steps

A solution of diisopropylamine (9.7 ml, 70 mmoles) in 150 ml of dry tetrahydrofuran at -40° C. under argon was treated with 39 ml (64.5 mmoles) of 1.71N n-butyllithium is hexane and the pale yellow solution stirred at -40° C. for 20 minutes. The solution was cooled to -78° C., and a solution of 7.95 g (30 mmoles) of N-(t-butoxycarbonyl)glycine, benzyl ester in 30 ml of dry tetrahydrofuran was dripped in over 5 minutes, resulting in a dark yellow solution, and, after 20 minutes, a slight turbidity. After 0.5 hours, a solution of 2.42 g (2.0 ml, 34.5 mmoles) of cyclobutanone in 30 ml of tetrahydrofuran was added. The resulting yellow turbid mixture was stirred at -78° C. for 15 minutes, then placed in a 0° C. ice bath for 2 hours. At an internal temperature of -25° C. (1 hour), the solution became clear, and at -15° C. turned dark purple. It was stirred at 0° C. for 0.5 hours, then treated with 3.96 g (66 mmoles) of glacial acetic acid in 15 ml of tetrahydrofuran, giving a turbid, light yellow mixture. This was poured into 500 ml of cold water and extracted twice with ethyl acetate. The extracts were washed with 2% potassium bisulfate, 5% sodium bicarbonate, and brine, dried (sodium sulfate) and evaporated to a thick oil. Chromatography on 800 ml of LPS-1 in hexane:ethyl acetate (2:1) and combination of the product fractions (Rf=0.29) gave 7.8 g of product as an oil.

Provenance & Evidence