Dept. of Chemistry
Oregon Graduate Center
Synthesis of sulfonium ylids, 3-dimethylsulfonioindolide, 3-dimethylsulfonio- 2-methylindolide and 3-dimethylsulfonio-2-phenylindolide were accomplished. Carbon-13.and [superscript 1] H nmr of ylids and the related thioethers and sulfonium salts were studied in an attempt to describe the electronic changes occurring within the indole system to accommodate ylid stabilization. In a study of their physical properties, it was discovered that the sulfonium salt <===> ylid system displayed a hysteresis during acid - base titration. The cause for the hysteresis was shown to be a result of covalent hydration (probably of the indole C2-C3 double bond). The uv spectra of the ylid and its analogs differed in aqueous and nonaqueous solvents suggesting that a chemical reaction occurred in protic solution. The [superscript 1] H nmr of sulfonium salts in protic solvents revealed the formation of a new species in the solution. This new species, upon acid - base titration exhibited a titration hysteresis identical to that previously observed in titration of either sulfonium salt or ylid. The mass spectra of the sulfonium salts and ylids by different techniques (EI, EI with rapid sample heating and FD) were obtained; by the newly developed technique of electron ionization with rapid heating and photoplate ion recording, indole sulfonium salt "hydrates" exhibit ions assignable as sulfonium salt hydrate species.
Park, Kyong-Hwi, "Indole 3-dimethylsulfonium ylids a study of their chemical and physical properties" (1978). Scholar Archive. 61.