Propriolic acid

Stille macrocyclization. Several macrocylic antibiotics contain a y-oxo-a, y3-unsaturated ester group. Macrolides of this type can be obtained by Stille intramolecular coupling.1 The substrates are available from Mitsunobu esterification of propriolic acid with an w-hydroxy ester followed by hydrostannylation to give /3-stannyl alkcnoates I as a 1 1 mixture of (Z)- and (E)-isomcrs. Selective saponification of the methyl ester... 

Daly, A.M., Bunker, P.R., and Kukolich, S.G. (2010) Evidence for proton tunneling from the microwave spectrum of the formic acid-propriolic acid dimer./. Chem. Phys., 132,... 

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