We have irecently reported' the results of an extensive study in the mass spectral fragmentation of isotetronic acids (a-hyclroxybutenolides, 3-methoxy-2(5H)- furanones). The corresponding methyl ethers show considerably different behaviour under electron im- pact, and therefore a knowledge of this behaviour makes additional structural information available. In- terest in isotetronic acid methyl ethers is increasing, not only as isomers of naturally occurring antibiotic ...
