Org Prep Daily

November 13, 2006

N-TBS-propiolactam and N-TBS-pyrrolidone

Filed under: procedures — milkshake @ 2:40 pm

lactam1.gif

DBU 11.7mL (78mmol) was added to a slurry of propiolactam 4.902g (68.9mmol, Aldrich) and TBS-Cl 11.43g (75.9mmol) in anh DMF (30mL) with cooling on ambient water bath. The reaction was stirred at RT for 3 hours at ambient bath and the obtained heterogennous mixture was quenched by addition of saturated aqueous ammonium chloride 200mL. The mixture was extracted with ether twice (2x250mL). The organic extracts were washed with water (250mL), combined, dried (MgSO4) and evaporated. The residue was distilled on highvac (0.5Torr). After a small front fraction (1.5g), the pure product distilled at 58-61C/0.5Torr. Y=10.823g (84.5%) of a clear liquid.

1H(CDCl3, 400MHz): 3.154(br t, 4.3Hz, 2H), 3.028(br t, 4.4Hz, 2H), 0.914(s, 9H), 0.191(s, 6H); 13C(CDCl3,100MHz):172.70, 39.18, 36.87, 26.23(3C), 18.75, -5.88 (2C)

lactam2.gif

Analogous procedure: DBU 16.5mL (110mmol) was added to a slurry of 2-pyrrolidone 8.511g (100mmol, Aldrich) and TBS-Cl 15.073g (100mmol) in anh DMF (40mL) with cooling on ambient water bath and the mixture was then stirred for 1 hour at RT. Y=17.641g (88.5%) of a colorless liquid, b.p. 69-71C/0.5Torr

1H(CDCl3, 400MHz): 3.354(t, 6.6Hz, 2H), 2.292(t, 8.2Hz, 2H), 1.990(m, 2H), 0.911(s, 9H), 0.228(s, 6H); 13C(CDCl3, 100MHz): 183.14, 48.16, 33.10, 26.85(3C), 22.14, 19.63,-4.88(2C)

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