Possibility of a non-amino acid pathway in the biosynthesis of marine-derived oxazoles

Takao Ichino, Hirokazu Arimoto, Daisuke Uemura
2006 Chemical Communications  
General Remarks 1 H and 13 C NMR spectra were recorded on a JEOL JNM-EX270 or a JEOL JNM-A400 specrometer with CDCl 3 as a solvent. General synthetic procedures for oxazoles To a solution of cyclododecanone (5.00g, 27.4 mmol) and trimethylorthoformate (6.00 mL, 54.8 mmol) in dichloromethane (28 mL) was added slowly BF 3 etherate (7.00 mL, 55.2 mmol) at -78°C. The solution was stirred for 30 min. N, N-diisopropyl ethylamine (14.3 mL, 82.1 mmol) was added, and the reaction mixture was further
more » ... ure was further stirred for 90 min at the same temperature. The reaction was quenched by addition of sat. NH 4 Claq. (50 mL), and the resulting mixture was extracted with dichloromethane. The extract was washed with brine, dried, and concentrated to dryness. Chromatography of the residue (silicagel, hexane-ether) gave 2-dimethoxymethyl-cyclododecanone 1 (7.03 g, quant.) as a pale yellow oil. 2) Oxime formation and subsequent Beckmann rearrangement to oxazole 3 (Method A) A solution of 1 (130 mg, 507 µmol) and HONH 2 HCl (70 mg, 1.01 mmol) in pyridine (1.0 mL, 12.4 mmol) was stirred at 50°C for 8 hr. The reaction mixture was diluted with ether (20 mL), and washed with the sat. NH 4 Claq. (50 mL). The organic phase was
doi:10.1039/b517149k pmid:16609790 fatcat:dtqwcsx3xnarlienp4xq5ca574