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Synlett
Volumn , Issue 14, 2009, Pages 2257-2260
An approach to the synthesis of anti-β2,3-amino acids: Application of β-trifluoroacetamidoorganozinc reagents
Author keywords

Alkylations; Amino acids; Cross coupling; Lactones; Zinc
Indexed keywords

AMINO ACID DERIVATIVE; BETA 2,3 AMINO ACID; COPPER; LACTONE; PALLADIUM; UNCLASSIFIED DRUG;
EID: 69249084546     PISSN: 09365214     EISSN: 14372096     Source Type: Journal    
DOI: 10.1055/s-0029-1217721     Document Type: Article
Times cited : (4)
References (34)
  • 22
    • 69249151981 scopus 로고    scopus 로고
    • Procedure for Lactone Alkylation Using a minor modification of conditions already reported for the alkylation of dianions of γ-N-trifluoroacetyl amino acid esters,19 n-BuLi (2.5 M in hexane, 5 mL, 12.5 mmol) was added dropwise to a stirred solution of DIPA (1.9 mL, 13.75 mmol) in THF (5 mL) at 0°C. The resulting solution was stirred for 15 min before being cooled to -78°C for the addition of the lactone 6 (985 mg, 5 mmol) in THF (28 mL, The reaction was stirred at the same temperature for a further hour before the electrophile (5 equiv) was added dropwise with careful monitoring of the internal temperature of the reaction to ensure it did not exceed -78°C. After stirring at -78°C for 18 h, the reaction was quenched with aq citric acid (10, 30 mL) before being extracted with EtOAc (3 x 50 mL) and the organic fractions combined, washed with brine (2 x 30 mL, dried (MgSO4) and evaporated under reduced pressure. The
    • 4) and evaporated under reduced pressure. The crude product was purified by silica gel column chromatography.
  • 23
    • 69249106346 scopus 로고    scopus 로고
    • Crystallographic data (excluding structure factors) for compound 9 has been deposited with the Cambridge Crystallographic Data Centre as supplementary publication number CCDC 733395.
    • Crystallographic data (excluding structure factors) for compound 9 has been deposited with the Cambridge Crystallographic Data Centre as supplementary publication number CCDC 733395.
  • 26
    • 69249098151 scopus 로고    scopus 로고
    • 4), and concentrated under reduced pressure to afford the crude product, which was purified by silica gel column chromatography.
    • 4), and concentrated under reduced pressure to afford the crude product, which was purified by silica gel column chromatography.
  • 28
    • 69249160211 scopus 로고    scopus 로고
    • General Procedure for Pd-Catalysed Cross-Coupling Zinc dust (195 mg, 3 mmol, 6 equiv) was placed in a dry 10 mL round-bottom flask with sidearm, containing a rugbyball-shaped magnetic stirrer. The flask was flushed with nitrogen, and dry DMF (0.2 mL) was added under nitrogen via syringe followed by catalytic iodine (40 mg, 0.15 mmol, 0.3 equiv, Effervescence was observed and the DMF changed from colourless to yellow and back again. A solution of the appropriate alkyl iodide (0.5 mmol) in DMF (0.3 mL) under nitrogen was transferred to the activated zinc suspension via syringe. The solution was stirred at r.t, and the insertion proceeded with a noticeable exotherm. When the solution had cooled, Pd2(dba)3 (11.0 mg, 0.0125 mmol, 2.5 mol, P(o-tol)3 (15 mg, 0.05 mmol, 10 mol, and the aryl iodide (1.3 equiv relative to the alkyl iodide) were added to the flask and the reaction stirred at r.t. overnight
    • 3 (15 mg, 0.05 mmol, 10 mol%) and the aryl iodide (1.3 equiv relative to the alkyl iodide) were added to the flask and the reaction stirred at r.t. overnight.
  • 32
    • 69249097321 scopus 로고    scopus 로고
    • General Procedure for Cu-Catalysed Allylation The organozinc reagent was formed as described above using zinc (6 equiv) and DMF (0.65 equiv) relative to the alkyl iodide. While the zinc insertion was in progress, CuBr•DMS (13 mol, was dried gently under vacuum in a separate flask until it changed from a white to a light green powder. Dry DMF (0.65 equiv) was then added, followed by the allyl chloride (1.3 equiv, Once the zinc insertion reached completion, stirring of the reaction mixture was stopped to allow the zinc powder to settle, and the supernatant was transferred to the solution of allyl chloride and copper catalyst via syringe. After stirring for 18 h at r.t, EtOAc (10 mL) was added and the reaction stirred for a further 15 min. A further aliquot of EtOAc (30 mL) was added and the organic layer separated and washed successively with aq Na2S2O3 solution (1 M, 2 x 30 mL, H2O (30 mL) and brine (30 mL, dried MgSO 4
    • 4), and evaporated under reduced pressure to afford the crude product which was purified by silica gel column chromatography.

* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.