Dibutyl squarate → 1-Butoxy-2-(3-bromopropylamino)-1-cyclobutene-3,4-dione

Participants

Reaction Conditions

Reaction Steps

Solid 3-bromopropylamine hydrobromide (41.52 g, 0.1897 mole) was added with stirring to a solution of sodium hydroxide (7.73 g, contains 0.187 mole) in methanol (150 mL) at 22° C., stirred for 15 minutes, then cooled to 0° C. to give a hazy solution of bromopropylamine base. The solution of bromopropylamine base was added slowly (over 20 minutes) with vigorous stirring to the product of Step A in methanol at 0° C. The mixture was stirred at 22° C. for 1.5 hours, polish filtered through diatomaceous earth (washed through with 50 mL of methanol) and added with vigorous stirring to water (1060 mL). The stirred mixture was cooled to -10° C. over several hours. The solid was collected by filtration, washed well with water (0° C., 440 mL) and dried in vacuo to give 50.0 g (91.8% yield) of the title compound as an off-white solid; m.p.=66°-68° C.

Provenance & Evidence