| Abstract
| - Flow pyrolysis of 2-methyl-2-propyl 1‘-propenyl sulfoxide(9b) affords a 98:2 mixture of (Z)- and(E)-propanethial S-oxide ((Z)- and(E)-5b), both characterized by Fourier transformmicrowave (FT-MW) spectroscopy.Sulfines (Z)- and (E)-5b are alsoidentified by FT-MW in chopped onion volatiles and by NMR spectroscopyinonion extracts. Similarly, flow pyrolysis of 2-methyl-2-propylvinyl sulfoxide (9c) affords (Z)- and(E)-isomers ofethanethial S-oxide (5a), identified by FT-MWmethods. Pyrolysis in the presence of D2O affords(Z)-5a-d1 and(Z)-5a-d2 from9c and(Z)-5b-d1 from9b; (Z)-5b-d1is also produced when an onion is homogenized in D2O.Pyrolysisof 9c with ethyl propiolate gives ethyl(E)-3-(vinylsulfinyl)acrylate (10).Neat 5a at 100 °C gives acetaldehyde.Onstanding, 5b dimerizes totrans-3,4-diethyl-1,2-dithietane 1,1-dioxide(12a);Me3SiCHS+−O-(5f) undergoes ananalogous dimerization. Compound 5b shows moderatepotency as an anticarcinogen in inducing the enzymequinonereductase.
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