A. Trimethylsilylmethylmagnesium chloride. Magnesium turnings (10.7 g, 0.44 g-atom) are placed in a dry, 300-mL, four-necked, round-bottomed flask equipped with a Teflon-coated magnetic stirring bar, a 200-mL pressure-equalizing dropping funnel capped with a rubber septum, a thermometer, another rubber septum, and a reflux condenser connected to an argon flow line. The apparatus is flushed with argon, and an argon atmosphere is maintained throughout the reaction. Anhydrous diethyl ether (40 mL) (Note 1) and 0.1 mL of 1,2-dibromoethane are placed in the reaction flask with a syringe, and the mixture is stirred at room temperature for 15 min. The dropping funnel is charged with a solution of 45.4 g (0.37 mol) of chloromethyltrimethylsilane (Note 2) in 100 mL of anhydrous diethyl ether with a syringe. With stirring, about 10 mL of this solution is added at once. When the reaction has started (Note 3), the remaining solution is added dropwise at such a rate that a gentle reflux is maintained throughout the addition (addition time ca. 2 hr). After the exothermic reaction subsides, the resulting solution is stirred at reflux by heating for an additional 1 hr. The reaction mixture is cooled to room temperature, and is used in step B.

B. Trimethylsilyldiazomethane. (See (Note 4).) A dry, 1-L, four-necked, round-bottomed flask is equipped with a liquid paraffin-sealed mechanical stirrer (Note 5), a rubber septum, 200-mL pressure-equalizing dropping funnel capped with another rubber septum, and a reflux condenser connected to an argon flow line. The apparatus is flushed with argon, and an argon atmosphere is maintained throughout the reaction. A solution of 91.2 g (0.33 mol) of diphenyl phosphorazidate (Note 6) in 350 mL of anhydrous diethyl ether is placed in the flask with a syringe. The rubber septum is quickly replaced by a low-temperature thermometer. The Grignard reagent prepared in Step A is transferred to the dropping funnel with a syringe. The flask is cooled with an ice–sodium chloride bath, and the stirring is started. When the internal temperature reaches −10°C, the Grignard reagent is added dropwise at such a rate that the internal temperature is maintained below 0°C (addition time ca. 1.5 hr) (Note 7). After the addition is complete, the ice–salt bath is replaced with an ice bath and the mixture is stirred for 2 hr, then allowed to stand in the ice bath for 14–16 hr. The reaction mixture is cooled again to −15°C with an ice–sodium chloride bath. With vigorous stirring, 35 mL of cold water is carefully added dropwise at such a rate that the internal temperature is maintained below 0°C (addition time about 1 hr), and the stirring is continued for 0.5 hr (Note 8). The reaction mixture is then filtered by suction using a glass filter. The white solid is thoroughly washed with three 100-mL portions of diethyl ether. The combined filtrate is washed with two 100-mL portions of cold water and dried over anhydrous sodium sulfate. After the sodium sulfate is removed by filtration, the filtrate is placed in a 1-L, round-bottomed flask equipped with a Teflon-coated magnetic stirring bar and a 30-cm Vigreux column (15-mm diameter). With constant stirring by a magnetic stirrer, the solution is slowly concentrated to a volume of about 200 mL by distillation at atmospheric pressure with the bath temperature below 45°C. The concentration time requires about 6 hr (Note 9) and (Note 10). The remaining deep-yellow solution is distilled through the same apparatus under reduced pressure between 100 mm at 0°C (bath temperature) and 15 mm at 40°C (bath temperature) until no more volatile material comes over, and the distillate is collected in a receiver cooled in a dry ice–acetone bath. The distillate is dried again over anhydrous sodium sulfate. The drying agent is removed by filtration, and 100 mL of hexane (Note 11) is added to the filtrate. In a manner similar to that described above, this solution is slowly concentrated by distillation at atmospheric pressure through a 30-cm Vigreux column (15-mm diameter). The color of the distillate gradually becomes yellow. Concentration is continued until the temperature of the vapor reaches 68°C (final oil-bath temperature 87°C). The concentration requires about 3 hr (Note 9). Approximately 80–110 mL of the remaining yellow hexane solution contains 220–230 mmol of trimethylsilyldiazomethane (67–70% yield based on diphenyl phosphorazidate) (Note 12) and (Note 13). This hexane solution can be stored without decomposition for periods exceeding 6 months at 0°C with protection from light.