Diethyl squarate → HCID 54525291, compound

Participants

Reaction Steps

A solution of 3,4-diethoxy-3-cyclobutene-1,2-dione (10 g, 59 mmol) and (R)-2-amino-3,3-dimethylbutane (353 mL of a 0.2M solution in absolute ethanol, 71 mmol) was stirred at room temperature for 24 hours. Another portion of (R)-2-amino-3,3-dimethylbutane (150 mL of a 0.2M solution in absolute ethanol, 30 mmol) was added, and the resulting solution was stirred at room temperature for 24 hours. The slurry was filtered, and the filtrate concentrated under reduced pressure. The resulting solid was triturated with hexane:ethyl acetate (150:5 mL), and washed with hexane to give 9.78 g (74%) of a white solid: 1H NMR: (DMSO-d6): δ 8.72 and 8.50 (two d, 1H, rotamers), 4.65 (m, 2H), 3.90 and 3.42 (two m, H, rotamers), 1.37 and 1.35 (two overlapping t, 2H, rotamers), 1.10 (two overlapping d, 3H, rotamers), 0.85 and 0.84 (two s, 9H, rotamers) ppm. IR(KBr): 3150, 2950, 1800, 1700 cm-1 ; MS (m/z): 225 (M+); Anal. Calcd. for C12H19NO3 : C, 63.98; H, 8.50; N, 6.22. Found: C, 64.33; H, 8.54; N, 6.52.

Provenance & Evidence