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DOI: 10.1055/s-2004-820013
A New, Convenient, Highly Selective Free-Radical Hydroxymethylation of Heteroaromatic Bases by Persulfate Oxidation of Ethylene Glycol and Glycerol, Catalysed by AgNO3
Publication History
Publication Date:
24 February 2004 (online)
Abstract
A new, convenient and selective source of hydroxymethyl (•CH2OH) radical has been developed by persulfate oxidation of ethylene glycol with AgNO3 catalysis. The •CH2OH radical is selectively trapped by protonated heteroaromatic bases, providing a new, general process of hydroxymethylation; the importance of the β-scission of the alkoxyl radical intermediate is emphasised.
Key words
hydroxymethylation - heterocycles - free-radicals - diols - persulfate
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References
Typical Experimental Procedure: Lepidine (20 mmol), CF3COOH (20 mmol), (NH4)2S2O8 (80 mmol) and AgNO3 (2 mmol) were refluxed in H2O (75 mL) and ethylene glycol (75 mL) for 3 h. The solution was made basic by NaOH and extracted with CH2Cl2. GC analysis (quinoline as internal standard) revealed the presence of 2-hydroxymethyllepidine (18.5 mmol) and lepidine (1.3 mmol). The CH2Cl2 solution was evaporated and the residue gave, by flash chromato-graphy (hexane-EtOAc, 2:1) pure 2-hydroxymethyllepidine (17.1 mmol), identified by comparison with an authentic sample. The results in the Table 1 refer to GC analyses.