No abstract

Tcrom Ester of tert-Butoxycarbonyl-L-tyrosylglycylglycyl-L-phenylalaninyl-L-methionine. The tripeptide prepared above (210 mg, 0.30 mmol) was dissolved in dioxane (2 mL) and anisóle (0.5 mL) which had been saturated with hydrogen chloride. After 20 min at 25 °C the solvent was evaporated, and the residue was triturated with ether to give the hydrochloride salt of H-Gly-L-Phe-L-Met-OTcrom as a white powder (159 mg, 83%). This was dissolved in 5 mL of freshly distilled DMF containing tert-butoxycarbonyl-L-tyrosylglycine (88 mg, 0.26 mmol). The solution was cooled to 0 °C and treated with hydroxybenzotriazole (40 mg), triethylamine (36 mL), and dicyclohexylcarbodiimide (65 mg). After 2 h at 0 °C and 15 h at 25 °C, water and ethyl acetate were added, the slurry was filtered, and the filtrate was evaporated, ultimately at 0.1 mm. The resulting residue was taken up in ethyl acetate, washed with water, 0.5 M citric acid, 5% sodium bicarbonate, and water, and then dried and evaporated. The resulting oil was dried by repeated evaporation of acetonitrile, and the residue was triturated with ethyl acetate to give a white powder (143 mg, 64%) which was homogeneous by TLC (CHC13-CH30H, 9:1): [a}\ -11.5°( c 1.7, CH30H-CHC13, 3:1, v/v).

No abstract

[reaction: see text] A fast, flexible, and efficient approach for the stereocontrolled synthesis of enamides has been developed starting from lactams and amides through the use of imides. This new approach provides access to enamide systems not easily or currently accessible through other approaches.