Ethyl chloroformate → HCID 14024256, compound

Participants

Reaction Conditions

Reaction Steps

A solution of 1-(2-(tert-butyldimethylsiloxy)ethyl)-3-methyltriazene, 3, (24.0 g, 0.11 mol) in anhydrous ether (70 mL) was added dropwise over 1.5 h to a stirred suspension of potassium hydride (- 6 g, 0.15 mol) in anhydrous ether containing 50 mg (1.3×10-4 mol) of dicyclohexano-18-crown-6 ether at 25° C. under nitrogen. Stirring was continued for 30 min until hydrogen evolution had ceased. The reaction mixture was cooled to -30° C. and then ethyl chloroformate (13.1 g, 0.12 mol) in anhydrous ether (70 mL) was added dropwise with stirring over 2 h. the reaction was stirred and allowed to warm gradually to 0° C. over 30 minutes, at which time hydrolysis was accomplished by the careful addition of 250 mL of 10% ammonium hydroxide solution containing 10% (w/v) ammonium chloride. The ether layer was separated and the aqueous layer was reextracted with pentane (100 mL). The ether and pentane layers were combined and dried twice over anhydrous sodium sulfate, and concentrated on a rotary evaporator at 25° C. Distillation of 1/10 of the crude product at reduced pressure using a short path distillation head gave 1.68 g (6.45×10-2 mol, 58.6% yield based on the fraction of total product distilled) of 1-(2-(tert-butyldimethylsiloxy)ethyl)-3-carboethoxy-3-methyltriazene, 4a: bp 90°-95° C. (0.07 mm); IR(Cl4) 2960, 2940, 2860, 1725, 1160, 840 cm -1 ; 1H NMR (CDCl3, Me4Si) δ 0.04 (6H,s), 0,87 (9H,s), 1.37 (3H,t,J=7 Hz), 3.24 (3H,s), 3.92 (2H,m), 4.94 (2H,m), 4.38 (2H,q,J=7 Hz); proton decoupled 13C NMR (CDCl3, Me4Si) δ-5.36, 14.45, 18.21, 25.89, 29.41, 61.20, 62.87, 63.87, 154.5. The crude product was determined to be sufficiently pure to be used directly in the following reaction.

Provenance & Evidence