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Acid‐Catalysed or Radical‐Promoted Allylic Substitution of 2‐Methylene‐2,3‐dihydrobenzofuran‐3‐ols with Thiol Derivatives: a Novel and Expedient Synthesis of 2‐(Thiomethyl)benzofurans
Author(s) -
Gabriele Bartolo,
Mancuso Raffaella,
Salerno Giuseppe
Publication year - 2010
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201000289
Subject(s) - chemistry , thiophenol , allylic rearrangement , methylene , medicinal chemistry , free radical addition , thiol , radical initiator , organic chemistry , radical , substitution reaction , catalysis , monomer , polymer
The 2‐thiomethylbenzofuran derivatives 3 are conveniently prepared in good yields through the reactions between the readily available 2‐methylene‐2,3‐dihydrobenzofuran‐3‐ols 1 and the thiol derivatives 2 (including alkyl thiols, thiophenol, and thioacetic acid). The allylic substitution process may be either acid‐catalysed or promoted by radical initiators. In the first case, the reactions are carried out at 90 °C in 1,2‐dimethoxyethane (DME) as the solvent in the presence of H 2 SO 4 as the proton source. The radical‐promoted reactions take place in DME at 90 °C in the presence of azobis(isobutyronitrile) (AIBN) or benzoyl peroxide (BP) as the radical initiator.