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Synlett
Volumn , Issue 2, 2008, Pages 273-277
Synthetic routes towards cryptophycin unit A diastereomers
Author keywords

Addition reactions; Cuprates; Diastereoselectivity; Natural products; Oxidations
Indexed keywords

CRYPTOPHYCIN A; DEPSIPEPTIDE; HYDROXYACID; UNCLASSIFIED DRUG;
EID: 38849201716     PISSN: 09365214     EISSN: None     Source Type: Journal    
DOI: 10.1055/s-2007-1000868     Document Type: Article
Times cited : (3)
References (33)
  • 17
    • 38849126393 scopus 로고    scopus 로고
    • Synthesis of 4b Copper(I) iodide (25.34 mmol, 4.826 g) was dried for 2 h in high vacuum at 100°C, deoxygenated three times with argon and suspended in anhyd toluene (52 mL, The mixture was cooled to-78°C, then MeLi (1.4 M) in Et2O (18.1 mL) was added over 20 min. While the reaction mixture was warmed to -40°C for 15 min, the suspension turned bright yellow. The mixture was cooled to -78°C again and BF 3·OEt2 (25.2 mmol, 3.58 g, 3.10 mL) was added dropwise and the mixture was stirred for 15 min at -78°C. Then a solution of (E)-ethyl 3, 4R,5R)-2,2-dimethyl-5-phenyl-1,3-dioxolan-4- yl]acrylate (3, 7.24 mmol, 2.000 g) in anhyd toluene (5 mL) was added dropwise and after the addition was complete, the reaction mixture was stirred for 16 h at -78°C. A 9:1 mixture of aq NH4Cl solution and 25% aq NH 4OH solution (6 mL) was added over 30 min at -78°C, and the cooling bath was
    • 4. The solvent was removed under vacuum (50°C). The crude product was purified by flash chromatography (hexane-EtOAc, 12:1) yielding (R)-ethyl 3-[(4R,5R)-2,2-dimethyl-5-phenyl-1,3-dioxolan-4- yl]butanoate (4b, 1.106 g, 52%, 92% de) as a slightly yellow, highly viscous oil. For the analytical data see ref. 4.
  • 27
    • 0001213599 scopus 로고    scopus 로고
    • For a review, see
    • (g) For a review, see: Mengel, A.; Reiser, O. Chem. Rev. 1999, 99, 1191.
    • (1999) Chem. Rev , vol.99 , pp. 1191
    • Mengel, A.1    Reiser, O.2
  • 32
    • 38849177007 scopus 로고    scopus 로고
    • Synthesis of 7b: NaHMDS (2 M, 0.68 mmol, 0.34 mL) in THF (2.14 mL) was cooled to -78°C, then a solution of (R)-ethyl 3, 4R,5R)-2,2-dimethyl-5-phenyl-1,3-dioxolan-4-yl]butanoate (4b, 0.68 mmol, 0.200 g) in anhyd THF (1.6 mL) was added over 15 min and the mixture was stirred at -78°C over 75 min. Then, racemic 3-phenyl-2-(phenyl-sulfonyl)-1,2-oxaziridine (0.95 mmol, 0.248 g, in anhyd THF (1.6 mL) was added over 15 min and the mixture stirred at -78°C until the reaction was complete (approx. 1 h, Then, sat. NH4Cl solution (1.5 mL) was added over 15 min at -78°C and the mixture allowed to reach r.t. Afterwards, Et2O (50 mL) and H2O (10 mL) were added, the layers separated and the aqueous layer extracted three times with Et 2O (50 mL, The combined organic layers were washed twice with H 2O (25 mL) and sat. NaCl solution 25 mL, dried over Na 2SO4, and the solv
    • +; found: 638.7.
  • 33
    • 38849099244 scopus 로고    scopus 로고
    • CCDC 668175 (7b) and 668176 (9a) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/ data_request/cif.
    • CCDC 668175 (7b) and 668176 (9a) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/ data_request/cif.

* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.