Diethyl squarate → HCID 59050120, compound

HRID 1265225Notes

Reaction equation

[NH2:1][C:2]1[CH:3]=[C:4]([C:8]2[CH:13]=[CH:12][C:11]([O:14][CH2:15][C@@H:16]([C:37]([O:39][CH3:40])=[O:38])[NH:17][C:18]([C:31]3[CH:36]=[CH:35][CH:34]=[CH:33][CH:32]=3)([C:25]3[CH:30]=[CH:29][CH:28]=[CH:27][CH:26]=3)[C:19]3[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=3)=[CH:10][CH:9]=2)[CH:5]=[CH:6][CH:7]=1.[CH2:41]([O:43][C:44]1[C:45](=O)[C:46](=[O:51])[C:47]=1[O:48]CC)[CH3:42]>C(Cl)Cl.CCOC(C)=O>[CH2:41]([O:43][C:44]1[C:47](=[O:48])[C:46](=[O:51])[C:45]=1[NH:1][C:2]1[CH:3]=[C:4]([C:8]2[CH:9]=[CH:10][C:11]([O:14][CH2:15][C@@H:16]([C:37]([O:39][CH3:40])=[O:38])[NH:17][C:18]([C:19]3[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=3)([C:31]3[CH:32]=[CH:33][CH:34]=[CH:35][CH:36]=3)[C:25]3[CH:26]=[CH:27][CH:28]=[CH:29][CH:30]=3)=[CH:12][CH:13]=2)[CH:5]=[CH:6][CH:7]=1)[CH3:42]

Participants

Conditions

Temperature: 65 °C

Procedure

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).

Workup

temperatureto cool to rt
filtrationThe solution was filtered over a pad of silica gel
washeluted with CH2Cl2/EtOAc 9:1
washUnreacted 3,4-diethoxy-3-cyclobutene-1,2-dion eluted first

Sources & evidence

ORD record: ord-d08752779e7e4a27a8dc9234b0359c2a
Source dataset: uspto-grants-2003_04
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US06545029B2

Reaction notes

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