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Bz NH
Bn
O
120a
1-(Benzyloxy)but-3-yn-2-yl 2-(benzamido)-3-phenylpropanoate (120a). Oxazolone 55a (365
mg, 1.45 mmol) was dissolved in CH2Cl2 and alcohol 116a (329 mg, 1.89 mmol) was added,
followed by Et3N (100 µL, 0.72 mmol). The solution was concentrated under vacuum, resulting
in a viscous oil. After 1h the reaction mixture was re-dissolved in benzene (1 mL) and purified
by flash chromatography (gradient elution, hexanes-EtOAc, 1 : 0 to 4 : 1, v/v) to afford 120a
O
OBn
(335 mg, 54%) as a mixture of diastereomers in 1 : 1 ratio.
1 H NMR (300 MHz, CDCl3): δ 7.72 (d, J = 7.3 Hz, 2H), 7.54-7.17 (m, 13H), 6.54 (t, J = 6.0 Hz,
1H), 5.68-5.61 (m, 1H), 5.22-5.14 (m, 1H), 4.67-4.59 (m, 2H), 3.84-3.70 (m, 2H), 3.39-3.23 (m,
2H), 2.60 (d, J = 2.2 Hz, 0.5H), 2.52 (d, J = 2.1 Hz, 0.5H); IR (thin film): ν 3288, 3030, 2931,
2124, 1749, 1648 cm -1 .
Bz NH
Bn
O
120b
1-(tert-Butyldimethylsilyloxy)but-3-yn-2-yl 2-(benzamido)-3-phenylpropanoate (120b).
Oxazolone 55a (1.50 g, 5.97 mmol) was dissolved in CH2Cl2 (3 mL) and alcohol 116b (1.10 g,
6.57 mmol) was added, followed by Et3N (83 µL, 0.60 mmol). The solution was concentrated
under vacuum, resulting in a viscous oil. After 30 min the reaction mixture was re-dissolved in
benzene (~1 mL) and purified by flash chromatography (gradient elution, hexanes-EtOAc, 20 : 1
to 10 : 1, v/v) to afford 120b (790 mg, 32%) as a mixture of diastereomers in 1 : 1 ratio.
1 H NMR (300 MHz, CDCl3): δ 7.85 (d, J = 7.0 Hz, 2H), 7.65-7.54 (m, 3H), 7.42-7.32 (m, 5H),
O
194
OTBS