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DOI: 10.1055/s-2007-977443
Synthesis of 7,8-Benzo-4-hydroxy-1,9-diazabicyclo[3.3.1]non-3-enes by Cyclization of 1,3-Bis(silyl enol ethers) with Quinazoline
Publikationsverlauf
Publikationsdatum:
18. April 2007 (online)
Abstract
Functionalized 7,8-benzo-4-hydroxy-1,9-diazabicyclo[3.3.1]non-3-enes were prepared by one-pot cyclization of 1,3-bis(silyl enol ethers) with quinazolines.
Key words
cyclizations - N-heterocycles - iminium salts - quinazolines - silyl enol ethers
- 1
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References and Notes
General Procedure for the Cyclization of Quinazolines with 1,3-Bis(silyl enol ethers)
To a CH2Cl2 soln (40 mL) of quinazoline (0.521 g, 4.0 mmol) was added the 1,3-bis(silyl enol ether) (5.6 mmol) and methyl chloroformate (1.512 g, 16.0 mmol) at 0 °C. The solution was stirred for 2 h at 0 °C and for 12 h at 20 °C. The solvent was removed in vacuo. The residue was purified by chromatography (silica gel, heptane → heptane-EtOAc = 2:1).
Synthesis of 3a
Starting from quinazoline (0.521 g, 4.0 mmol), 2a (1.460 g, 5.6 mmol) and methyl chloroformate (1.512 g, 16.0 mmol), 3a was obtained as a colorless solid (0.750 g, 52%). 1H NMR (250 MHz, CDCl3): δ = 2.41 (dd, 2
J = 17.5 Hz, 3
J = 1.5 Hz, 1 H, CH2), 2.99 (br dd, 1 H, CH2), 3.76 (s, 3 H, OCH3), 3.80 (s, 3 H, OCH3), 3.87 (s, 3 H, OCH3), 5.40 (br, 1 H, NCHCH2), 7.03-7.13 (m, 2 H, CH, Ar), 7.20-7.26 (m, 1 H, CH, Ar), 7.38 (br, 1 H, NCH), 7.75 (br, 1 H, CH, Ar), 12.26 (s, 1 H, OH). 13C NMR (75.5 MHz, CDCl3): δ = 38.0 (CH2), 48.7 (br, NCHCH2), 52.0, 53.2, 53.3 (OCH3), 58.9 (NCH), 98.0 (CCO2CH3), 124.2, 124.4, 126.8, 127.6 (CH, Ar), 126.3, 134.4 (br, C, Ar), 153.4, 154.0 (NCO), 170.6 (COO), 173.2 (br, COH). IR (mull): 3080 (w), 1707 (s), 1652 (m), 1613 (m), 1494 (m), 1335 (m), 1287 (s), 1263 (m), 1230 (s), 1196 (m), 1142 (m), 1111 (m), 1064 (m), 1039 (m), 1008 (m), 954 (w), 873 (w), 824 (w), 778 (m), 737 (w) cm-1. MS (EI, 70 eV): m/z (%) = 362 (10) [M+], 303 (100), 271 (36), 212 (23), 180 (21), 239 (13). Anal. Calcd for C17H18N2O7 (362.33): C, 56.35; H, 5.01; N, 7.73. Found: C, 56.35; H, 5.13; N, 7.46.
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