Carbon-chain homologations condensation

Condensation. Generation of stabilized free radicals from dithiocarbonate esters via C—S bond cleavage is promoted by BusSnSnBus. By providing an alkene and a trapping agent, homologation of a carbon chain while performing functionalization, for example,... 

The Henry reaction, or nitroaldo reaction, is one of the classic carbon-chain formation methods utilized in organic synthesis. It involves the condensation of nitroalkanes with aldehydes or ketones in the presence of bases (often catalytic amount) to afford the mixtures of diastereomeric 2-nitroalcohols, which in turn can be converted into other useful synthetic intermediates, such as 2-aminoalcohols, a-hydroxyketones, homologous ketones, and perhaps most importantly, nitroalkenes through various functional transformations. 

Methods of chain extensions generally use linear sugars with free aldehydes mostly prepared via dithioacetal formation, protection of the remaining hydroxyl groups and aldehyde recovery. This allows one to use all methods applicable to aldehydes. Among others, the condensation of ethyl diazoacetate has been studied in detail by L6pez-Herrera [207] in a new synthesis of KDO by a two carbon homologation of an open-chain mannose derivative. 

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