Nonreductive Desulfenylation of 3-Indolyl Sulfides. Improved Syntheses of 2-Substituted Indoles and 2-Indolyl Sulfides

Article abstract of DOI:10.1021/jo00100a045

Desulfenylation of 3-indolyl sulfides to the corresponding 3-unsubstituted indoles is usually carried out under reductive conditions, thus accommodating only substituents which are resistant to reduction.We have developed a nonreductive procedure for removal of a sulfide at the 3-position of indoles, using trifluoroacetic acid in the presence of a thiol as trapping agent, which is compatible with a large array of functionalities on the indole ring.In addition, the desulfenylation occurs selectively at the 3-position of the indole, and sulfide groups at other positions of the molecule remain untouched.Thus, indole 2,3-bis-sulfides are selectively desulfenylated at the 3-position, affording 3-unsubstituted 2-indolyl sulfides.This methodology broadens the use of sulfide as a protecting group for the 3-position of indoles.