Trimethylaluminum, reaction with

This procedure, which is based on the work of Ishii and co-workers, affords a mild and general method for converting a wide variety of esters to primary, secondary, and tertiary amides (Table 1). While the preparation of the tertiary amide, N,N-dimethylcyclohexanecarboxamide, described here is carried out in benzene, aluminum amides derived from ammonia and a variety of primary amines have been prepared by reaction with trimethylaluminum in dichloromethane and utilized for aminolysis in this solvent. Although 1 equivalent of the dimethylaluminum amides from amines was generally sufficient for high conversion within 5-48 hours, best results were obtained when 2 equivalents of the aluminum reagent from ammonia was used. Diethyl-aluminum amides can also effect aminolysis, but with considerably slower rates. 

Dibutyl ether is the only solvent suitable for this reaction. Dibutyl ether has relatively low volatility and complexes with trimethylaluminum without solvent decomposition. Dibutyl ether complexes with BBr, sulTiciently strongly to slow the rate of reaction ofBBrj with AIMe, to a safe rate. Boron tribromide reacts explosively with trimethylaluminum in diethyl ether or anisole solutions because of the weak complexation between these solvents and BBr,. Tetra-hydrofuran and p-dioxane undergo decom X)sition reactions with trimethylaluminum, and thus are unsuitable as solvents in this synthesis. 

Methyl ketones. Nitriles (aliphatic and aromatic) are converted into methyl ketones by reaction with trimethylaluminum in the presence of various catalysts,... 

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