Ethyl chloroformate → HCID 20334482, compound

Participants

Reaction Conditions

Reaction Steps

About 225 g. of 2-(β-carboxyethyl)-2-(m-methoxyphenyl)cyclohexanone were mixed with 125 g. of triethylamine and about 20 g. of sodium sulfate. A solution of 99 g. of ethyl chloroformate in 3250 ml. of anhydrous ether was added in dropwise fashion, thus converting the carboxyethyl group to an acid anhydride. The reaction mixture was stirred for about 1 hour at about 0° C. at which point 89 g. of sodium azide in 350 ml. of water were added in dropwise fashion. After the addition had been completed, the reaction mixture was stirred for an additional two hours at 0° C. The ether layer was then separated. 2-(β-Azidoformylethyl)-2-(m-methoxyphenyl)cyclohexanone formed in the above reaction was isolated as an oil by evaporation of the ether in vacuo. The residual oil was dissolved in 3.5 l. of benzene, and the solution heated at refluxing temperature for about 1.5 hours. The benzene was removed by evaporation in vacuo. By this procedure the azidoformyl group was rearranged under Curtius conditions to yield the corresponding isocyanate. The benzene was removed by evaporation in vacuo. The isocyanate remaining as a residue was next hydrolyzed to the cyclic imine by heating overnight in a mixture containing 1200 ml. of water, 1200 ml. of glacial acetic acid and 1200 ml. of 12N aqueous hydrochloric acid. The hydrolysis mixture was cooled and then made strongly basic with 50 percent aqueous sodium hydroxide. 3a-(m-methoxyphenyl)-2,3,3a,4,5,6,7-heptahydroindole thus produced was extracted into ether, and the ether layer separated, washed with water and dried. Evaporation of the ether layer to dryness yielded 153.2 g. of 3a-(m-methoxyphenyl)-2,3,3a,4,5,6,7-heptahydroindole, distilling at about 140° C. at 0.07 mm/g. (For comparison, see Langlois et al., Tetrahedron, 27, 5641 (1971) compound 10 and page 5647, table 4, compound 42).

Provenance & Evidence