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Organic Letters
Volumn 9, Issue 14, 2007, Pages 2673-2676
Cyclopentanone ring expansion leading to functionalized δ-lactams: Short synthesis of simple sedum alkaloids
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EID: 34547424961     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol070960r     Document Type: Article
Times cited : (24)
References (39)
  • 26
    • 0037138704 scopus 로고    scopus 로고
    • Enantiomerically pure epoxide made according to the procedure in the following: Schaus, S. E.; Brandes, B. D.; Larrow, J. F.; Tokunaga, M.; Hansen, K. B.; Gould, A. E.; Furrow, M. E.; Jacobsen, E. J. Am. Chem. Soc. 2002, 124, 1307-1315.
    • Enantiomerically pure epoxide made according to the procedure in the following: Schaus, S. E.; Brandes, B. D.; Larrow, J. F.; Tokunaga, M.; Hansen, K. B.; Gould, A. E.; Furrow, M. E.; Jacobsen, E. J. Am. Chem. Soc. 2002, 124, 1307-1315.
  • 38
    • 34547473315 scopus 로고    scopus 로고
    • Compounds 10a and 10b exist as a nonseparable mixture of diastereomers. To separate them, it was necessary to functionalize the free alcohol in the lactam side chain as a tert-butyldimethylsilyl ether.
    • Compounds 10a and 10b exist as a nonseparable mixture of diastereomers. To separate them, it was necessary to functionalize the free alcohol in the lactam side chain as a tert-butyldimethylsilyl ether.
  • 39
    • 84858087220 scopus 로고    scopus 로고
    • Typical procedure: Formation of lactones 4a and 4b from epoxide 2f: A 25 mL flask was charged with (cyclopentenyloxy) trimethylsilane (1, 0.300 g, 1.92 mmol) and dissolved in THF (1.5 mL, To this, at 0 °C, was added MeLi (1.26 mL, 2.02 mmol, 1.6 M in Et2O) dropwise over the course of about 1 min. After 5 min, the reaction was cooled to -78 °C, and (R)-1,2-epoxypentane (2f, 0.083 g, 0.96 mmol) in THF (1.5 mL) was added via canula. The reaction was stirred for 5 min before BF 3·Et2O (0.122 mL,0.96 mmol, neat) was added very slowly (ldrop/4 s, using a 100 μL syringe, while cooling the needle with a piece of dry ice. After 1 h, the reaction was quenched with phosphate buffer (3.0 mL, pH 7.0) and warmed to room temperature. The mixture was extracted with Et2O 3 × 25 mL, and the combined organics were dried over MgSO4 and concentrated in vacuo. The crude product was purifie
    • 3). Formation of lactam 6b: A 10 mL flask was charged with azido lactone 5b (0.022 g, 1.04 mmol), methanol (1 mL), and Lindlar's catalyst (0.19 g, 1.04 mmol).

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