Deprotonation process nitroalkanes

Silylation of Products of Conjugated Addition of Nucleophiles to a-Nitroolefins Nitroalkane anions can be generated not only by deprotonation of nitroalkanes (various modifications of these process were considered above) but also by the conjugated addition of nucleophiles 56 to a-nitroalkenes (42) (Scheme 3.56, Table 3.2). 

Two general type of processes that proceed by way of a putative enolate-metal complex have been documented (1) those in which the metaiioenoiate nucleophile is generated following deprotonation of C-H acid 257—>258, and (2) those in which the metaiioenoiate is generated upon desilylative metallation of an enol silane 261—>262 (Scheme 21). Examples of the former processes have been documented and utilize activated C-H acids with pK (H2O)<20 such as isonitrile esters 259, nitroalkanes 260, and ketones. Fewer cases have been reported for the catalytic addition of enol silanes through a putative metaiioenoiate intermedi-... 

The Nef reaction1 2 is the conversion of nitroalkanes to ketones and aldehydes through treatment with base followed by acid.3 4,5,6 For example, deprotonation of 1-nitrobutane (1) with aqueous NaOH followed by addition of excess aqueous sulfuric acid afforded butyraldehyde (2) in 85% yield (isolated as the oxime derivative).7 These reactions proceed via intermediate nitronate anions, which are subsequently hydrolyzed to afford the carbonyl products. The overall transformation leads to formal polarity reversal of the carbon bearing the nitro group from a nucleophilic species to an electrophilic carbonyl carbon. Although the classical conditions for this process are quite harsh, a number of alternative procedures that employ mild reaction conditions have been developed. 

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