Diethyl squarate → HCID 59050120, compound

Participants

Reaction Conditions

Reaction Steps

The compound of Example 3 (1.50 g, 2.8 mmol, 1 equiv) was dissolved in 3,4-diethoxy-3 cyclobutene-1,2-dione (2.1 mL, 14.2 mmol, 5 equiv). The reaction mixture was stirred at 60-70° C. for 1 h. It was then allowed to cool to rt and diluted with CH2Cl2/EtOAc 9:1 (12 mL). The solution was filtered over a pad of silica gel and eluted with CH2Cl2/EtOAc 9:1. Unreacted 3,4-diethoxy-3-cyclobutene-1,2-dion eluted first followed by the title compound. Yield 0.68 g, 36.7%. 1H NMR (CDCl3, 7.72-7.51 (m, 8H); 7.48-7.32 (m, 3H); 7.29-7.03 (m, 10H); 6.94 (d, 2H); 4.94 (q, 2H); 4.29 (dd, 1H); 4.14 (dd, 1H); 3.85-3.69 (m, 1H); 3.23 (s, 3H); 2.90 (d, 1H); 1.55 (t, 3H). MS (ESI) 675 (M+Na), 653 (M+H), 243 (CPh3).

Provenance & Evidence