tert-Butyl N-(1-ethoxycyclopropyl)carbamate (CAS NO.: 28750-48-3), which is also known as , (1-ethoxycyclopropyl)-, 1,1-dimethylethyl ester, could be produced through the following synthesis routes.

A. silver salt. A 3-l., two-necked, round-bottomed flask equipped with a mechanical stirrer and a pressure-equalizing dropping funnel is charged with a solution of 28.9 g. (0.292 mole) of succinimide in 1.2 l. of absolute ethanol. A solution of 48.58 g. (0.2860 mole) of silver nitrate in 200 ml. of dimethyl sulfoxide is added in one portion. The resulting solution is stirred as 700 ml. (0.280 mole) of 0.400 M sodium ethoxide in ethanol is added dropwise over 1.5 hours. The off-white silver salt begins to precipitate after ca. 140 ml. of the sodium ethoxide solution has been added. Stirring is continued for 45 minutes after the addition is completed, and the reaction mixture is then stored in a refrigerator at ca. 5° overnight to complete the precipitation and aggregation of the product.

The precipitate is collected on filter paper in a Büchner funnel by vacuum filtration and washed with 100 ml. of absolute ethanol. The solid is slurried in three 75-ml. portions of distilled water, 100 ml. of absolute ethanol, two 100-ml. portions of reagent grade acetone, and two 100-ml. portions of anhydrous ethyl ether. The filter cake is pressed dry in the funnel with suction using a piece of rubber dam, transferred to a tared, 500-ml., round-bottomed flask, and dried under reduced pressure (0.01 mm.) at room temperature for 24 hours, yielding 51–54 g. (88–94%) of the silver salt of succinimide.

B. 2-Ethoxypyrrolin-5-one. The flask containing 51–54 g. (0.25–0.26 mole) of succinimide silver salt is equipped with a magnetic stirring bar, a heating mantle, and reflux condenser bearing a silica gel drying tube. The solid is suspended in 295 ml. of dry chloroform, and 51.4 g. (26.4 ml., 0.330 mole) of ethyl iodide is added in one portion. The flask is covered with aluminum foil, and the mixture is stirred vigorously and heated under reflux for 48 hours. The mixture is cooled, the silver iodide is removed by vacuum filtration through Celite, and the filter cake is washed well with dry chloroform. The filtrate is concentrated by rotary evaporation to a mixture of a dark liquid and a white solid identified as succinimide. Anhydrous diethyl ether is added to dissolve the liquid, and the resulting suspension is filtered through a plug of glass wool, separating 7.7–11.5 g. of succinimide. The ether is removed from the filtrate by rotary evaporation at aspirator pressure, and the residual liquid is distilled under reduced pressure with a short-path distillation apparatus. The product is collected at 74–82° (0.01 mm.) as a faintly yellow oil which crystallizes in the freezer. The yield is 11.5–16.7 g. (32–46% based on sodium ethoxide in Part A).

C. tert-Butyl N-(1-ethoxycyclopropyl)carbamate. A three-necked, cylindrical irradiation vessel is equipped with a magnetic stirring bar, a water-jacketed quartz immersion well, an inert gas-inlet, and a gas-exit tube connected to a bubbler. The vessel is charged with 6.26 g. (0.0493 mole) of redistilled 2-ethoxypyrrolin-5-one and 180 ml. of dry tert-butyl alcohol. The solution is stirred and degassed by bubbling or argon through the gas-inlet tube for 15 minutes. The degassed solution is stirred and irradiated with ultraviolet light from a 450-watt, Hanovia, medium-pressure, mercury lamp filtered through a Vycor glass sleeve. During the irradiation an atmosphere of nitrogen or argon is maintained, and the lamp is cooled with warm water (35–40°) circulated through the cooling jacket of the immersion well. The progress of the irradiation is monitored by GC. When 90% of the 2-ethoxypyrrolin-5-one has reacted, the irradiation is stopped. The solution is transferred to a 250-ml., round-bottomed flask equipped with a magnetic stirring bar and an air-cooled reflux condenser mounted with a T-shaped nitrogen inlet. Nitrogen is passed through the apparatus for 30 minutes, after which the solution is stirred and heated at reflux under a nitrogen atmosphere for 20 hours. The solvent is removed by rotary evaporation, and the residual orange oil is refrigerated to induce crystallization. Sublimation of the solid at 35–40° (0.05 mm.) affords 5.5–6.3 g. (56–64%) of the carbamate as white needles, m.p. 38–40°.

Notice: The photochemical reaction in Part C should be carried out behind a light-absorbent cover or shield. Protective goggles should be worn to avoid exposure of the eyes to ultraviolet light.