Trimethylsilyl-2-methylcyclohexanone

Ethereal methyllithium added at 0 under Ng via syringe to a soln. of hexa-methyldisilane in anhydrous hexamethylphosphoramide, stirred 15 min. to complete the prepn. of trimethylsilyllithium, anhydrous tetrahydrofuran added, immediately chilled to -78 , a soln. of 2-cyclohexenone in tetrahydrofuran added dropwise, stirred an additional 5 min., methyl iodide injected, allowed to warm to 0 , poured into pentane, and treated with water -> fra 5-3-trimethylsilyl-2-methylcyclohexanone. Y 97%. F. e. without alkylation s. W. C. Still, J. Org. Chem. 41, 3063 (1976). 

Allenyl Silyl enol ethers, 86 Allyl alcohol trimethylsilyl ether, 84 Allyl carbonates, 114-15 9 Allyl-ay 2 octalone, 34-5 2-Allyl-2 methylcyclohexanone, 106 (Allyldimethylsilyl)methyl chloride, 58, 59 (AUyldimethylsilyl)methylmagnesium chloride, 59... 

In their paper on the preparation of trimethylsilyl enol ethers, House et al. [1] illustrate the generation of lithium enolates with the reaction between 2-methylcyclohexanone and LDA using 1,2-dimethoxyethane as a solvent. The authors do not indicate a temperature range for the lithiation of the ketone, but we found the deprotonation of a variety of ketones to proceed extremely fast and with excellent results at temperatures in the region of — 70 °C. In view of the possibility of aldol condensation, dropwise addition of the ketone to the LDA solution seems advisable. Attempts to prepare enolates from aldehydes RCH2CH=0 and LDA gave, after quenching with trimethylchlorosilane, only unidentified resinous products. 

Methoxytrimethylsilane, 123 Methyl acetoacetate, 92 Methyl bromoacetate, 107 Methyl 11-hydroxyundecanoate, 58 Methyl lithium, 27,28 Methyl 10-undecenoate, 58 2-Methyl-l,3-dithiane, 81 (I I ,SS)-Methyl-3-phenyldimethyl-silyl-3-phenylpropionic acid, 53-4 2-Methyl-3-Phenylprop-2-enal, 111 2-Methyl-2-trimethylsilyl-l, 3-dithiane, 81 2-Methyl-I-(trimethylsilyloxy)cyclo-hex-I-ene, 100,109 2-Methyl-1 -trimethylsilyloxy-cyclo-hex-6-ene, 100 2-Methyl-2-trimethylsilyloxy-pentan-3-one, 133 2-Methylacetophenone, 42-3 2-Methylbutyraldehyde, 85 2-Methylcyclohexanone, 99, 100 2-Methylcyclohexenone, 132 4-Methyldec-4-ene, 67-8 Methylenation, 63 2-Methylpropen-l-ol, 132 Methyltriphenylphosphonium bromide, 27 Michael addition, 85 Monohydridosilanes, 128 Monohydroalumination, 29... 

Cleavage of enol trimethylsilyl ethers or enol acetates by methyllithium (entries 1 and 3, Scheme 1.3) as a route to specific enolate formation is limited by the availability of these materials. Preparation of the enol trimethylsilyl ethers and enol acetates from the corresponding ketones usually affords a mixture of the two possible derivatives, which must be then separated. It is sometimes possible to find conditions that favor the formation of one isomer for example, reaction of 2-methylcyclohexanone with lithium diisopropylamide and trimethylchlorosilane affords the less highly substituted enol ether preferentially by 99 1 over the more highly substituted one (kinetically controlled conditions). ... 

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