Dibutyl squarate → 4-[(2-Butoxy-3,4-dioxo-cyclobut-1-enylamino)-methyl]-3-chloro-benzonitrile

Participants

Reaction Steps

A solution of 3,4-dibutoxy-3-cyclobutene-1,2-dione (2.263 g, 10 mmol) and 2-chloro-4-cyanobenzylamine (1.666 g, 10 mmol, Example 2, Step 3) in tetrahydrofuran (25 mL) was stirred at room temperature for 22 hours. The residue remaining after removal of solvent was dissolved in chloroform and was chromatographed (flash, ethyl acetate/hexane) on silica. The solid isolated from the appropriate fractions was recrystallized from ethyl acetate to provide 2.427 g of a white solid: mp 147.5°-149° C. MS (m/z) 318 (M+). HPLC indicates a major component (>99%).

Provenance & Evidence