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Synlett 2006(12): 1829-1834  
DOI: 10.1055/s-2006-947356
LETTER
© Georg Thieme Verlag Stuttgart · New York

Cerium(IV) Ammonium Nitrate (CAN): A Very Efficient Reagent for the Synthesis of Tertiary Ethers

E. J. Alvarez-Manzaneda*a, R. Chabouna, E. Alvareza, E. Cabreraa, R. Alvarez-Manzanedab, A. Haidoura, J. M. Ramosa
a Departamento de Química Orgánica, Facultad de Ciencias, Instituto de Biotecnología, Universidad de Granada, 18071 Granada, Spain, +34(958)248089
e-Mail: eamr@ugr.es;
b Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Almería, 04120 Almería, Spain
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Publikationsverlauf

Received 14 March 2006
Publikationsdatum:
24. Juli 2006 (online)

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Abstract

Treatment of tertiary 1,4- and 1,5-diols with cerium ammonium nitrate at room temperature led to the corresponding tetrahydrofuran and tetrahydropyran derivatives in high yield and stereoselectivity. Utilizing this methodology, manoyl oxide (25a) and a variety of fragrant compounds, such as linalool oxide (8), caparrapi oxide (12), ambrox (14) and other related amber-gris-type odorants have been synthesized; 16 examples are described.

Key words

cyclizations - diols - ethers - natural products - stereo­selectivity

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Typical Experimental Procedure. To a deoxygenated solution of compound (1 mmol) in MeCN (10 mL) was added solid CAN (1.2 mmol) and the mixture was stirred under an argon atmosphere at r.t. for the specified time (Table [1] ). The progress of the reaction was monitored by TLC. After completion of the reaction, the solvent was removed and the residue was diluted with Et2O (20 mL), washed with H2O, brine and dried over anhyd Na2SO4. After removal of the solvent the residue was subjected to column chromatography on silica gel. Elution with 5% Et2O-hexane afforded the pure product.

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All new compounds were fully characterized spectroscopically and had satisfactory HRMS data.
Selected data:
Compound 23: 1H NMR (400 MHz, CDCl3): δ = 1.28 (s, 3 H), 1.19 (s, 3 H), 0.85 (t, J = 3.8 Hz, 3 H), 0.85 (s, 3 H), 0.79 (s, 3 H), 0.76 (s, 3 H). 13C NMR (100 MHz, CDCl3): δ = 74.6 (C), 72.9 (C), 58.3 (CH), 56.5 (CH), 43.1 (CH2), 42.2 (CH2), 39.2 (CH2), 37.9 (CH2), 36.9 (C), 35.7 (CH2), 33.4 (CH3), 33.3 (C), 27.3 (CH3), 24.9 (CH3), 21.3 (CH3), 19.9 (CH2), 18.7 (CH2), 15.8 (CH3), 15.4 (CH2), 8.1 (CH3). IR (film): 1638, 1463, 1374, 1278, 1119, 1006, 959, 845 cm-1. MS (EI) m/z (relative intensity) = 292 (3), 263 (22), 245 (100), 223 (5), 177 (18), 137 (34), 123 (23). HRMS (FAB): m/z calcd for C20H36ONa: 315.2664; found: 315.2650.
Compound 29: 1H NMR (400 MHz, CDCl3): δ = 3.90 (d, J = 10.8 Hz, 1 H), 3.72 (d, J = 10.8 Hz, 1 H), 2.06 (s, 3 H), 1.26 (s, 3 H), 1.21 (s, 3 H), 0.84 (s, 3 H), 0.77 (s, 3 H), 0.75 (s, 3 H). 13C NMR (100 MHz, CDCl3): δ = 171.2 (C), 75.2 (C), 72.9 (CH2), 71.8 (C), 57.5 (CH), 56.5 (CH), 43.0 (CH2), 42.2 (CH2), 39.1 (CH2), 36.9 (C), 33.7 (CH2), 33.4 (CH3), 33.3 (C), 25.0 (CH3), 24.8 (CH3), 21.4 (CH3), 21.2 (CH3), 19.9 (CH2), 18.6 (CH2), 15.7 (CH3), 14.9 (CH3). IR (film): 1744, 1464, 1377, 1241, 1122, 1044, 994, 757 cm-1. MS (EI) m/z (relative intensity) = 336 (16), 303(7), 276 (10), 263 (12), 245 (60), 191 (10), 137 (28). HRMS (FAB): m/z calcd for C21H36O3Na: 359.2562; found: 359.2574.

Compound 31: 1H NMR (400 MHz, CDCl3): δ = 3.71 (s, 3 H), 2.13 (ddd, J = 14.0, 8.4, 4.6 Hz, 1 H), 1.85 (dt, J = 12.4, 3.3 Hz, 1 H), 1.79 (m, 2 H), 1.34 (s, 3 H), 1.22 (s, 3 H), 0.88 (dd, J = 12.5, 1.9 Hz, 1 H), 0.83 (s, 3 H), 0.76 (s, 6 H). 13C NMR (100 MHz, CDCl3): δ = 177.1 (C), 76.1 (C), 74.7 (C), 56.3 (CH), 52.4 (CH3) 52.2 (CH), 42.7 (CH2), 41.9 (CH2), 39.0 (CH2), 37.2 (C), 33.3 (CH3), 33.2 (C), 31.3 (CH2), 28.1 (CH3), 25.6 (CH3), 21.5 (CH3), 19.9 (CH2), 18.5 (CH2), 15.0 (CH3), 14.7 (CH3). IR (film): 1738, 1461, 1378, 1283, 1103, 992, 892, 849, 760 cm-1. MS (EI) m/z (relative intensity) = 323 (22), 307 (18), 263 (19), 245 (68), 196 (8), 137 (36). HRMS (FAB): m/z calcd for C20H34O3Na: 345.2406; found: 345.2412.
Compound 35: 1H NMR (400 MHz, CDCl3): δ = 3.32 (d, J = 10.6 Hz, 1 H), 3.07 (d, J = 10.6 Hz, 1 H), 2.32 (s, 1 H), 1.29 (s, 3 H), 1.16 (s, 3 H), 1.10 (dd, J = 12.6, 2.4 Hz, 1 H), 0.99 (dd, J = 12.2, 1.5 Hz, 1 H), 0.85 (s, 3 H), 0.79 (s, 3 H), 0.76 (s, 3 H). 13C NMR (100 MHz, CDCl3): δ = 75.5 (C), 73.3 (C), 70.9 (CH2), 58.2 (CH), 56.4 (CH), 43.1 (CH2), 42.2 (CH2), 39.2 (CH2), 36.9 (C), 33.4 (CH3), 33.3 (C), 32.5 (CH2), 25.1 (CH3), 24.5 (CH3), 21.3 (CH3), 19.8 (CH2), 18.6 (CH2), 15.8 (CH3), 15.0 (CH3). IR (film): 3455, 1463, 1377, 1259, 1121, 1052, 960, 755 cm-1. MS (EI) m/z (relative intensity) = 294 (8), 263 (14), 245 (76), 191 (10), 149 (12), 137 (40), 83 (71). HRMS (FAB): m/z calcd for C19H34O2Na: 317.2456; found: 317.2448.