ChemInform Abstract: Decarboxylative Isomerization of N‐Acyl‐2‐oxazolidinones to 2‐Oxazolines.

Abstract

Oxazole derivatives R 0220Decarboxylative Isomerization of N-Acyl-2-oxazolidinones to 2-Oxazolines. -The mild and general method for the isomerization proceeds without epimerization. -(MAY, A. E.; WILLOUGHBY, P. H.; HOYE*, T. R.; J. Org. Chem. 73 (2008) 8, 3292-3294; Dep. Chem., Univ. Minn., Minneapolis, MN 55455, USA; Eng.) -Jannicke 35-120

Phosphorus-Based Organocatalysis for the Dehydrative Cyclization of N-(2-Hydroxyethyl)amides into 2-Oxazolines

“…13 (S)-4-Benzyl-2-phenyl-4,5-dihydrooxazole (2g). 55 According to the general procedure, the reaction was carried out between TAP-1 (3 mol %, 6.87 mg) and 1g (0.5 mmol) in dehydrated toluene:DMF (6.8:0.2 mL) at 120 °C (heat source: oil bath) for 12 h. Upon completion, 2g was obtained as colorless oil after flash column chromatography on silica gel (eluent: 0 to 10% ethyl acetate in nhexane) (85.4 mg, 0.36 mmol, crude yield: 79%, isolated yield: 72%). R f = 0.52 (25% EtOAc in n-hexane).…”

“…1 H NMR (600 MHz, CDCl 3 ) δ 7.94−7.96 (d, J = 7.6 Hz, 2H), 7.22−7.49 (m, 8H), 4.57−4.60 (m, 1H), 4.33−4.36 (t, J = 7.8 Hz, 1H), 4.13−4.16 (t, J = 7.2 Hz, 1H), 3.23−3.26 (dd, J = 13.8, 4.8 Hz, 1H), 2.71−2.75 (dd, J = 13.8, 9.0 Hz, 1H). 13 55 [α] D rt = +8.0 (c 0.67, CHCl 3 ). (S)-2-(4-Chlorophenyl)-4-isopropyl-4,5-dihydrooxazole (2h).…”