We report here reactions of alkyl sulfides with benzynes thermally generated by the hexadehydro-Diels-Alder (HDDA) cycloisomerization. The initially produced 1,3-betaine (o-sulfonium/aryl carbanion) undergoes intramolecular proton transfer to generate a more stable S-aryl sulfur ylide. This can react in various manners, including engaging weak acids (HA) in the reaction medium. This can produce transient ion pairs ArSR2+A- that proceed to the products ArSR + RA. When cyclic sulfides are used, A- opens the ring and is incorporated into the product, an outcome that constitutes a versatile, three-component coupling process.
Bibliographical noteFunding Information:
Support for this research was provided by the National Institutes of Health (GM65597). V.P. was supported by a Gleysteen-Heisig fellowship for undergraduate students. NMR spectra were recorded using instrumentation purchased with funds provided by the NIH Shared Instrumentation Grant program (S10OD011952). We thank Sean Ross and Juntian Zhang for providing samples of and procedures for preparing tetraynes 13 and precursor to 21c.
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