Rhodium-Mediated [3,3]-Sulfonium Ylide Rearrangement of Indoles

Significance

The authors report an interesting [3,3]-rearrangement of 2-thio-3-alkylindoles in the presence of Rh(II) which furnishes indolines containing quaternary carbon centers in high yields and diastereoselectivities. Substitution of the thioether group with sterically bulky arene units provided the highest level of diastereoselection. To demonstrate the potential of their products, the authors list several derivatizations including the synthesis of a halogenated spirocycle. While a chiral Rh(II) complex is used in this reaction, enantioselectivities were quite low.