Lithium amides reacted with tellurium under atmospheric pressure of carbon monoxide to yield lithium carbamotelluroates which were trapped with alkyl halides to give Te-alkyl carbamotelluroates in good yields. Results of control experiments suggested that lithium carbamotelluroates were formed by the reaction of tellurium with carbamoyllithiums generated in situ from lithium amides and carbon monoxide. It was revealed also that yields were imprwed when tellurium was preliminarily treated with Iithium amides prior to the introduction of carbon monoxide into the reaction media.Carbamoyllithiums are attractive reagents for nucleophilic introduction of carbamoyl moieties into organic molecules [ 13. Their synthetic utility has been demonstrated clearly by our recent study which achieved efficient generation of carbamoyllithiums from carbamotelluroates by lithium-tellurium exchange reactions and their successful trapping with a variety of electrophiles [lb]. In order to make this transformation practically useful for organic synthesis, general and convenient synthetic methods of carbamotelluroates are strongly demanded. The hitherto known methods for their preparation are limited only to the substitution of . As for the selenium analogues, Se-alkyl carbamoselenoates were obtained in good yields by the alkylation with alkyl halides of ammonium carbamoselenoates generated in situ from selenium, carbon monoxide, and secondary amines [3]. This reaction can be carried out conveniently at room temperature under atmospheric pressure of carbon monoxide. These successful results led us to examine the reaction of tellurium with carbon monoxide and amines under similar conditions, but no reaction took place and tellurium was recovered unchanged. Since this may be due to the low reactivity of tellurium, we then employed lithium amides instead of amines and found that tellurium reacts with lithium amides and carbon monoxide at low temperatures to form lithium carbamotelluroates which undergo alkylation with alkyl halides to yield Te-alkyl carbamotelluroates.A typical example is as follows. To a flamedried, 30 mL, three-necked, round bottom flask equipped with an Ar inlet, a CO inlet, and a rubber septum, 10 mL of THF and 5 mmol of piperidine were placed under Ar. The solution was cooled to -78"C, and 5.5 mmol of "BuLi (1.6 N in hexane) was injected with stirring. After 15 minutes, finely ground elemental tellurium (638 mg, 5 mmol) was added and the mixture was allowed to warm to 10°C. All of the tellurium pieces disappeared within 1 hour to give a dark violet homogeneous solution. The solution was cooled to -78°C again, purged with carbon monoxide, and stirred for 2 hours, resulting in the absorption of 129 mL (5.8 mmol) of carbon monoxide. At this stage, lithium piperidi-0 1993 VCH Publishers, Inc.