Adamantane-l-carboxylic acid chloride

To a stirred solution of [4-(2-pyrimidinyl)piperazino]ethylamine (2.0 g, 0.01 mol) in 50 ml of methylene chloride, adamantane-l-carboxylic acid chloride (3.6 g, 0.018 mol) and triethylamine (2.9 g, 0.015 mol) were added. Stirring was continued at room temperature overnight. The methylene chloride solution was washed with water, dried over anhydrous sodium sulfate and evaporated under reduced pressure. The remaining residue was subjected to preparative HPLC. The residue was dissolved in ethyl acetate (10 ml) and subjected to flash chromatography using a 9 inch column of silica gel and ethyl acetate as the eluent. The N-[2-[4-(2-pyrimidinyl)-l-piperazinyl]ethyl]tricyclo[3.3.1.1(3,7)] decane-l-carboxamide was separated. 

Adamantane-l-carboxylic acid chloride [1, 15, before 1-Adamantyl chloroformatej. Mol. wt. 198.69, m.p. 54 -56°. Supplier A. 

Hydroxyl group Adamantane-l-carboxylic acid chloride. 0-Benzoylpropionic acid. Ethyl vinyl ether. 4-Methoxy-5,6-dihydro-2H-pyrane. p-Nitrophenyl chloroformate. 

The introduction of the trimethylsilyl chloride trapping technique" led to improved yields in the case of simple aliphatic esters. The initial silylated products are easily isolated and can be converted into the acyloins simply and in high yield. For simple aliphatic esters the yields are in the range 56-92%. Use of trimethylsilyl esters, rather than simple alkyl esters, leads to faster reactions, but lower yields.Substituted esters which have been successfully used in the newer procedure include ethyl 2-ethylhexanoate (83%), ethyl trimethylsilylacetate (90%)," ethyl 3-trimethylsilylpropionate (65%)," ethyl phenylacetate (48%)," ethyl 3-phenylpropionate (79%)" and 2-(2-methoxycarbonylethyl)-2-methyl-l,3-dioxolane derived from levulinic acid (65%)." In the case of ethyl adamantane-l-carboxylate the yield using the newer procedure is reported to be inferior to that using the earlier procedure. 

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