a b s t r a c tRegioselective hydration of a wide range of internal alkynes has been afforded in high to good yields by using PTSA in EtOH. The scope of the reaction of alkynes has been delineated. Arylaliphatic alkynes and diarylalkynes were regioselectively hydrated in good to excellent yields and short reaction times when the reaction was achieved under microwave irradiation. Moreover, diarylalkynes, arylenynes as well as diaryldiynes bearing a methoxy-or a thiomethyl substituent on the ortho position underwent a regioselective 5-endo-dig-cyclization to give a variety of 2-aryl-and 2-styrylbenzofuran or benzothiphene derivatives. We believe that, this new environmentally metal-free procedure combined to microwave irradiation would be in importance in the search of green laboratory-scale synthesis.

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A convenient and general approach to the synthesis of 2-substituted 3-bromobenzofurans and -benzothiophenes was developed. The procedure is based on the cyclization of ortho-substituted arylalkynes in the presence of N-methylpyrrolidin-2-one hydrotribromide (MPHT) as a soft and easy-tohandle electrophilic brominating reagent. Under mild reaction conditions, MPHT promoted the bromocyclization of

Hydration reactions of internal arylalkynes are efficiently performed using catalytic or stoichiometric amounts of TosOH in EtOH under microwave irradiation to give aryl ketones. Compared to thermal heating, the substrate scope can be successfully extended to weakly reactive alkynes. Unsymmetrical diarylalkynes are regioselectively hydrated. Some alkynols are additionally etherificated on the hydroxy group by the alcohol solvent. Diarylalkynes, arylenynes as well as diaryldiynes bearing a methoxy or a methylthio substituent on the ortho-position undergo a regioselective 5-endo-dig-cyclization to afford 2-substituted benzofuran and benzothiophene derivatives, respectively. -(JACUBERT, M.; PROVOT*, O.; PEYRAT, J.-F.; HAMZE, A.; BRION, J.-D.; ALAMI*, M.; Tetrahedron 66 (2010) 21, 3775-3787,