title: Gold(I)-catalyzed rearrangement of 3-silyloxy-1,5-enynes: an efficient synthesis of benzo[b]thiophenes, dibenzothiophenes, dibenzofurans, and indole derivatives.
abstract: With the IPr ligand (IPr=1,3-bis-(2,6-diisopropylphenyl)imidazol-2-ylidene) on gold(I) excellent yields in the benzanellation of 2-substituted thiophenes, benzothiophenes, pyrroles, benzofurans, and indoles were achieved. The 1-siloxybut-3-ynyl side chains, incorporated in the anellation, are easily accessible by the addition of a propargyl metal reagent to a formyl group and silylation of the alcohol. This conveniently allows an anellation at the position of the formyl group under mild conditions. All reactions involve a 2,3-shift of the side chain in the anellation step and thus, provide an easy access to specific substitution patterns. Only in the case of 2-substituted indoles with their highly nucleophilic 3-position a direct hydroarylation without shift is observed. On the other hand, 3-substituted indoles give the same products as 2-substituted indoles. Then, a 3,2-shift in the indole ring system has to be involved.
authors.affiliation: Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany. hashmi@hashmi.de
authors.forename: A Stephen K
authors.initials: AS
authors.lastname: Hashmi
authors.forename: Weibo
authors.initials: W
authors.lastname: Yang
authors.forename: Frank
authors.initials: F
authors.lastname: Rominger
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D001572:Benzofurans / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D020650:Combinatorial Chemistry Techniques; D006046:Gold / Q000737:chemistry*; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D017646:Organosilicon Compounds / Q000737:chemistry*; D013876:Thiophenes / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000480:Alkynes; D001572:Benzofurans; D007211:Indoles; D017646:Organosilicon Compounds; D013876:Thiophenes; D006046:Gold; C016366:dibenzothiophene