A mild, general preparation of N-acyl aziridines and 2-substituted 4(S)-benzyloxazolines

Abstract

The conversion of a wide range of carboxylic acids into their acyl imidazolides with subsequent addition of an aziridine rapidly gives a quantitative yield of the corresponding N-acyl aziridines.Iodide (or bromide) ion catalysed rearrangement of N-acyl 2(S)-benzylaziridines 1 to oxazolines 6 proceeds quantitatively.

A total synthesis of (±)-biotin

“…Low solubility in ethereal solvents may have, in part, been responsible for the incomplete reduction. Complete reduction was achieved using s o d i~~m borohydride in aqueous ethanol (9) at reflux; however, the resulting dihydroxynitrile 90 proved difficult to purify so that conversion to the methyl ester 96 was effected to give, in 65% yield, material that could be purified by recrystallization and which was identical to that previously described (5).…”

“…Infrarcd spectra were recorded on eithcr Perkin-Elmer 528 or Acculab 6 instrumcnts. 9,.0~ '1 ~ri~tlec~n1~-10-o11c~ 4 A solution of 1.3-diacctylim~dazolin-hnc (3) (10 g, 59.5 mmol) in acctonc (230 mL, distilled from KMnOJ) and 3.4-clihydro-2-nicthoxy-2H-pyril11(70 niL) was placcd in an immersion wcll photochemical rcactos,' thcn dcoxygcnatcd with a strcam of nitrogcn for 0.5 11. Thc rcaction mixturc was thcn pliotolyscd for 10 h with a 450 W Hanovia lamp filtcrcd with Corcx.…”

An Efficient and Versatile Method for the Synthesis of Optically Active 2-Oxazolines: An Acid-catalyzed Condensation of Ortho Esters with Amino Alcohols

“…According to the general procedure (method A), ( S )-(−)- 2c (3.02 g, 20.0 mmol) was allowed to react with 1a (3.89 g, 24.0 mmol) in the presence of acetic acid (50 μL, 4 mol %). Kugelrohr distillation (63−65 °C, 120 mTorr) afforded the title compound (3.27 g, 93%) as a colorless oil: [α] 25 D −49.3° ( c 2.83, CHCl 3 ) [lit …”

Efficient Oxidative Synthesis of 2-Oxazolines

“…Molecular sieves (4 Å) were activated by microwave irradiation (3 × 3 min.) All re- 23,24 1u, 32 and 7 14b,33 have previously been described in the literature. Characterization data for all new compounds and for compounds whose data is not completely available in the literature (oxazolines 1b, 1h, and 1u) is given.…”