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Synlett
Volumn , Issue 4, 2009, Pages 611-614
New efficient synthesis of 5-ethoxyoxazoles and oxazolo[3,2-c]quinazolines via aza-Wittig reaction
Author keywords

Aza Wittig reaction; Carbodiimide; Imidoyl chloride; Oxazole; Oxazolo 3,2 c quinazoline
Indexed keywords

EID: 62349090516     PISSN: 09365214     EISSN: 14372096     Source Type: Journal    
DOI: 10.1055/s-0028-1087562     Document Type: Article
Times cited : (19)
References (30)
  • 27
    • 62349138182 scopus 로고    scopus 로고
    • Oxazoles 4 and 2-Acylaminopropanoates 5 To a stirred solution of azide 1 (1.0 mmol) in CH2Cl2 (10 mL) was added a solution of Ph3P (0.26 g, 1 mmol) in dry CH2Cl2 (5 mL) at r.t. After the reaction mixture was stirred for 2 h, acyl chloride (1.0 mmol) and Et3N (0.30 g, 3.0 mmol) were added at r.t, and the color of the solution turned yellow. After stirring for 4 h, the mixture was filtered to remove the Et3NHCl, and the filtrate was evaporated under reduced pressure. The crude product was purified by flash chromatography (5:1, PE-Et2O) to yield oxazoles 4 or 2-acylaminopropanoates 5. Spectral Data for Some Unreported Compounds Compound 4c: light yellow solid, mp 60-61°C. IR (KBr, 1620, 1487, 1282, 1093, 1005 cm-1. 1 NMR (400 MHz, CDCl3, δ, 7.68-7.21 (m, 4 H, ArH, 6.05 (s, 1 H, ArH, 4.00 q, J, 7.2 Hz, 2 H, OCH
    • 3)
  • 28
    • 62349098023 scopus 로고    scopus 로고
    • Iminophosphorane 6 To a stirred solution of 4i (1.15 g, 5 mmol) in CH2Cl2 (15 mL) was added a solution of Ph 3P (1.31 g, 5 mmol) in dry CH2Cl2 (10 mL, After the reaction mixture was stirred for 2 h, the solvent was removed under reduced pressure, and the residue was recrystallized from Et2O and EtOH (1:1; v/v) to give the iminophosphorane 6 (2.22 g, yield 96, light yellow crystals; mp 175-177°C. IR (KBr, 1606, 1468, 1435, 1353, 1271, 1118, 1035cm-1. 1 NMR (400 MHz, CDCl3, δ, 7.86-6.53 (m, 19 H, ArH, 6.23 (s, 1 H, ArH, 4.14 (q, J, 7.0 Hz, 2 H, OCH2, 1.45 (t, J, 7.0 Hz, 3 H, CH3, MS: m/z, 464 (100, M, 435 (65, 380 (92, 277 (18, 261 (10, 201 (11, 183 (16, 145 16, Anal. Calcd for C29H 25N2O2P: C, 74.99; H, 5.42; N, 6.03. Found: C, 74.77;
    • 2P: C, 74.99; H, 5.42; N, 6.03. Found: C, 74.77; H, 5.60; N, 6.12.
  • 29
    • 62349138496 scopus 로고    scopus 로고
    • Oxazolo[3,2-c]quinazolines 8 To a solution of iminophosphorane 6 (0.46 g, 1 mmol) in dry CH2Cl2 (10 mL) was added aryl isocyanate (1 mmol) under nitrogen at r.t. The solution turned red immediately. After stirred for 1 h, the solvent was evaporated under reduced pressure, and the residue was recrystallized from Et2O and EtOH (1:1, v/v) to give oxazolo[3,2-c]quinazolines 8 as red crystals. Compound 8a: red crystals, mp 151°C (dec, IR (KBr, 1764, 1690, 1640, 1560, 1474, 1440, 1307, 1251 cm-1. 1 NMR (400 MHz, CDCl3, δ, 7.68-6.94 (m, 10 H, ArH, 4.39 (q, J, 7.0 Hz, 2 H, OCH2, 1.58 (t, J, 7.0 Hz, 3 H, CH 3, 13C NMR (150 MHz, CDCl3, δ, 157.5, 153.2, 150.8, 147.2, 143.4, 135.5, 129.1, 128.4, 125.6, 123.3, 121.7, 120.4, 102.7, 87.9, 70.5, 14.3. MS: m/z, 305 53, M, 248
    • 2: C, 66.87; H, 4.36;N, 13.00. Found: C, 66.73; H, 4.54; N, 13.25.
  • 30
    • 62349119276 scopus 로고    scopus 로고
    • Oxazolo[3,2-c]quinazoline 10 To a solution of iminophosphorane 6 (0.46 g, 1 mmol) in MeCN (10 mL) was added CS 2 (1.50 g, 20 mmol, The mixture was heated to reflux for 10 h, the solvent was evaporated under reduced pressure, and the residue was recrystallized from EtOH to give oxazolo[3,2-c]quinazoline 10; yellow crystals, mp 138-139°C. IR (KBr, 1654, 1635, 1484, 1434, 1321, 1298, 1176, 1054 cm-1. 1 NMR (400 MHz, CDCl3, δ, 7.94-7.38 (m, 5 H, ArH, 4.47 (q, J, 7.2 Hz, 2 H, OCH 2, 1.61 (t, J, 7.2 Hz, 3 H, CH3, 13C NMR (100 MHz, CDCl3, δ, 157.4, 148.4, 138.4, 135.7, 128.2, 126.8, 125.0, 121.5, 115.5, 91.3, 71.0, 14.2. MS: m/z, 246 (37, M, 218 (25, 190 (28, 162 (100, 134 34, Anal. Calcd for C 12H10N2O2S: C, 58.52; H, 4.09; N, 11.37. Found: C, 58.5
    • 2S: C, 58.52; H, 4.09; N, 11.37. Found: C, 58.59; H, 4.21; N, 11.41.

* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.