(E)-N-(3-phenyl-2-buten-1-yl)benzamide → (5RS, 6SR)-2,6-diphenyl-6-methyl-5,6-dihydro-4H-1,3-oxazin-5-ol

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Reaction Steps

(5RS, 6SR)-6-Methyl-2,6-diphenyl-5,6-dihydro-4H-1,3-oxazin-5-ol may be obtained in the following manner: working as in Example 22 for the preparation of (5RS, 6SR)-2-(2-fluorophenyl)-6-phenyl-5,6-dihydro-4H-1,3-oxazin-5-ol, but starting with (E)-N-(3-phenyl-2-buten-1-yl)benzamide (4.2 g), a 0.35 M solution (48 cc) of 3-chloroperbenzoic acid in dichloromethane and boron trifluoride etherate (2.6 g), and after purification of the oil obtained by chromatography on a column (height: 35 cm; diameter: 3 cm) of silica (0.2-0.063 mm), eluting with a mixture of cyclohexane and ethyl acetate (60:40 by volume) and collecting 30-cc fractions, fractions 9 to 17 being combined and concentrated to dryness under reduced pressure (4 kPa) at 45° C., followed by recrystallization of the residue obtained in isopropyl ether, (5RS, 6SR)-6-methyl-2,6-diphenyl-5,6-dihydro-4H-1,3-oxazin-5-ol (1.65 g, m.p. 130° C.) is obtained.

Provenance & Evidence