Regioselective oxidation of isoxazolidines to ketonitrones

Heterocycles

Volumn 70, Issue , 2006, Pages 107-112

  Iwamoto, Osamu ^a   Sekine, Miyuki ^a   Koshino, Hiroyuki ^b   Nagasawa, Kazuo ^a  

^a TOKYO UNIVERSITY OF AGRICULTURE AND TECHNOLOGY   (Japan)

^b INST OF PHYS AND CHEMICAL RESEARCH   (Japan)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 33947640661     PISSN: 03855414     EISSN: None     Source Type: Journal    
DOI: 10.3987/com-06-s(w)34     Document Type: Article

References (22)

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12. 3 However, in case of 2a, mixture of 3a and 4a (≈1 : 3) was obtained under the reaction conditions reported by Ali, i.e., 1.2 equiv. of m-CPBA in acetic acid at room temperature.
13. Preparation of optically active nitrone (8). Goti A., Cacciarini M., Cardona F., and Brandi A. Tetrahedron Lett. 40 (1999) 2853
14. In the reaction of 9 with lithium hydroxide at 0 °C, isomerization at C3 position took place and the subsequent hydrolysis occurred to give the corresponding carboxylic acid exclusively. When this hydrolysis reaction was performed at room temperature, a mixture of a- and ß-carboxylic acids at the C3 position was obtained (ratio: -1:1).Relative stereochemistry of 2h was determined by nOe using the compound after the Curtius rearrangement.
15. Isomerization between aldonitrone (3a) and ketonitrone (4a) was not observed under the reaction conditions.
16. Two equiv. of m-CPBA is required for the regioselective oxidation to ketonitrone (4), however, the role of the extra one equiv. of m-CPBA is not clear at this stage.
17. 2O3 aqueous solution was added to the reaction mixture, and the organic layer was extracted with EtOAc. Extracts were washed with sat-NaHC03 and brine, dried over MgS04, filtered and concentrated in vacuo. The residue was purified by column chromatography on silica gel (eluent; hexane : EtOAc = 3 : 1) to give 4c (13 mg, 50%).'H NMR (400 MHz, CDCl3) 6 5.12 (brs, 1 H), 4.11 (m, I H), 3.96 (m, 2H), 3.67 (dd, J= 5.0, 10.0 Hz, 1H), 3.54 (dd, J = 6.9, 10.0 Hz, 1H), 2.76 (m, 3H), 2.56 (m, 1H), 1.08 (m, 21H), 0.89 (s, 9H), 0.06 (s, 3H), 0.05 (s, 3H).
18. Llewellyn L.E. Nat. Prod. Rep. 23 (2006) 200
19. Total synthesis of STX (12);. Tanino H., Nakata T., Kaneko T., and Kishi Y. J. Am. Chem. Soc. 99 (1977) 2818
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21. Fleming J.J., and Du Bois J. J. Am. Chem. Soc. 128 (2006) 3926
22. 1H NMR (600 MHz, CDCI3) 6 9.23 (s, 1 H), 5.28 (dq, J = 3.5, 6.6 Hz, 1 H), 4.3 (d, J = 3.5 Hz, 1H), 4.15 (brdd, J = 5.0, 4.0 Hz, 1H), 3.25 (m, 1 H), 3.01 (m, 1 H), 2.64 (s, 3H), 2.10 (m, 1H), 2.04 (s, 3H), 2.00 (m, 1H), 1.93 (s, 3H), 1.48 (s, 9H), 1.30 (d, J = 6.6 Hz, 3H), 1.01 (brs, 21 H); '3C NMR (150 MHz, CDC13) 8 170.41, 169.70, 167.96, 162.94, 158.60, 86.13, 79.54, 75.92, 67.97, 62.57, 53.66, 30.46, 27.98, 25.32, 21.09, 19.22, 18.12, 17.82, 12.32.