Methyl acrylate synthon

Novak et a 1. prepared the synthon (82 R = Me) by application of the thiazolium salt catalysed addition of the aldehyde (92) to methyl acrylate. The desired keto-ester (93) was obtained together with the dimer (94) of the starting aldehyde. The ester (93) was readily transformed into the eyelopentenone (82 R =Me)... 

The 4-phospha-1,3-butadiene 77/80 serves as an effective synthon for the unknown H-substituted nitrile ylide 79 in [3+ 2]-cycloaddition reactions with a range of electron-poor dipolarophUes (e.g., reaction with DMAD gave 78 in 80% yield). Similar yields were also obtained using methyl propiolate, azodicaboxylic esters, ethyl acrylate, and acrylonitrile (39). The reactant was generated under very mild conditions from 75 as shown below. 

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