Ketones synthesis, organolithium reagents

These compounds are sources of the nucleophilic anion RC=C and their reaction with primary alkyl halides provides an effective synthesis of alkynes (Section 9 6) The nucleophilicity of acetylide anions is also evident m their reactions with aldehydes and ketones which are entirely analogous to those of Grignard and organolithium reagents... 

All that has been said in this section applies with equal force to the use of organo-lithium reagents in the synthesis of alcohols. Grignard reagents are one source of nucleophilic carbon organolithium reagents are another. Both have substantial carbanionic char acter in their- car bon-metal bonds and undergo the same kind of reaction with aldehydes and ketones. 

Synthesis of ketones using organolithium reagents with carboxylic acids (Section 18-8)... 

Lack of conjugation leads to increased reactivity, and N-acyl aziridines are useful in synthesis because they react with organo-lithium reagents only once to give ketones. No further reactions of the product ketone occur because the N-acyl aziridine is reactive enough to compete with it for the organolithium reagent. 

Synthesis of ketones. 5,6-Dihydro-1,3-oxazines are also useful for synthesis of ketones.9 Thus the 2-isopropenyl oxazine (l)10 reacts in THF with Grignard or organolithium reagents to give a 2,2-dialkyltetrahydro-l,3-oxazine (2), which on hydrolysis with oxalic acid gives an a-methyl ketone (3). An important feature of... 

Synthesis of ketones and aldehydes from acid chlorides (or esters) via reaction of N-methoxy-N-methylamides with a Grignard or organolithium reagent (see 1 edition). 

The synthesis of symmetrical ketones noted above was developed into a practicable method by use of 2 eq. of the organolithium reagent for 1 eq. of the isocyanide. The reaction involves formation of the nitrile followed by reaction of this product with another equivalent of the lithium reagent ... 

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