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Synlett
Volumn , Issue 9, 2008, Pages 1283-1286
Silica-supported tetramethylguanidine: An efficient solid base for aldol-type coupling of aldehydes with ethyl diazoacetate
Author keywords

hydroxy diazoesters; Aldol; Reusable catalyst; Silica; Tetramethylguanidine
Indexed keywords

ALDEHYDE DERIVATIVE; DIAZOACETIC ACID ETHYL ESTER; GUANIDINE DERIVATIVE; SILICON DIOXIDE;
EID: 45749129107     PISSN: 09365214     EISSN: None     Source Type: Journal    
DOI: 10.1055/s-2008-1072769     Document Type: Article
Times cited : (13)
References (29)
  • 27
    • 45749119446 scopus 로고    scopus 로고
    • Preparation of Silica-Based Catalysts; SiO2-TMG: 3-Chloropropyl-modified silica, 1 (5 g, 2.5% loading, Aldrich) was dispersed in dry hexane (50 mL) under nitrogen and then hexamethyldisilazane (HMDS, 5 mL) was added to the dispersion and refluxed for 8 h, cooled to r.t, filtered and washed with copious amount of hexane to get the trimethylsilylated chloropropyl modified silica 2. Trimethylsilylated chloropropyl modified silica, 2 (1 g) was stirred with tetramethylguanidine (TMG, 2 mmol) and Et3N (1 mmol) in MeOH (20 mL) under nitrogen at 110°C for 24 h. Afterwards the solid was separated by filtration and once again washed with toluene using Sohxlet for 24 h to afford SiO2-TMG (loading of TMG: 0.16 mmol/g, calculated from elemental analysis, SiO2-IMZ was prepared in a similar fashion using imidazole (loading of IMZ: 0.14 mmol/g, calculated from elemental analysis, SiO2-NH2 loading 1 mm
    • 2 (loading 1 mmol/g) was purchased from Aldrich.
  • 28
    • 45749135749 scopus 로고    scopus 로고
    • General Procedure for Aldol-Type Coupling of Aldehydes with EDA: A mixture of aldehyde (0.5 mmol, EDA (1.2 equiv, and SiO2-TMG (50 mg) in DMSO (1 mL) was stirred in a round-bottom flask at r.t. After completion of the reaction, as monitored by TLC, the mixture was diluted with EtOAc (10 mL) and the catalyst was filtered off. The filtrate was washed with sat. aq NH 4Cl solution, followed by brine. The organic layer was dried over anhydrous Na2SO4 and the solvent was evaporated under reduced pressure to get the crude product. The crude product was purified by chromatography on silica gel using hexane-EtOAc mixture as eluent to afford the corresponding α-diazo-β-hydroxy esters. Spectroscopic data of the new Compounds are as follows: 2-Diazo-3-hydroxy-3-(3-phenoxyphenyl)propionic Acid Ethyl Ester (Table 3, entry 7, FTIR (neat, 3441, 2982, 2099, 1680, 1586, 1483, 1291, 1243, 1113, 756 cm-1. 1H NMR 300 M
    • 5: C, 64.04; H, 5.66; N, 7.86. Found: C, 64.01; H, 5.68; N, 7.90.

* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.