Rcformatsky reaction

Reformatsky reaction. Tetrahydropyranyl esters are recommended for use in Rcformatsky reactions. They are formed from a-bromo acids in quantitative yield In dry benzene without need of an acid catalyst and they arc readily hydrolyzed by dilute hydrochloric acid. The Reformatsky reaction is generally conducted in THF at a temperature below 10". The reaction is more rapid if the zinc is activated with a trace of HgCI2. Yields of -hydroxy acids arc generally 70-90% when aldehydes are used, hul usually somewhat lower with ketones. 

Reformatsky reaction. In the presence of catalytic amounts of CISilCHOj, ethyl formate or orthoformate undergoes a tandem Rcformatsky reaction with a-bromopro-pionates (equation I). Three diastereomers, syn-syn, syn-anti, and anti-anti, are formed, typically in the ratio 49 42 9. 

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