Utilização de Dicalcogenetos de Diorganoíla como Reagente e Catalisador: Síntese de 3-(Organoilsselanil)benzo[b]furanos e de Fosforamidatos de Dialquila

Abstract

A new method was developed to synthesize 3-selanylorganyl benzo[b]furans from alkynylanisoles and diorganoyl diselenides. In this work Selectfluor® was used as oxidating reagent, wich presents low toxicity and high chemical and physical stability. In this new protocol, 11 benzofurans were synthesized (4 of which were not described in the literature) with yields ranging from 40-97% at 25 °C and short reactions times of 2 h. Additionally, this approach was extended to synthesize two 3-(selanyl)indoles. Also, diphenyl disulfide and ditelluride were capable to undergo this cyclization reaction. 19F and 77Se NMR experiments provided significant insight to the hypothesis of the generation of a RSeF species under the reaction conditions. In a second moment a new protocol was developed in wich diphenyl ditelluride (5 mol%) was able to promote the amination of H-phosphonates. The reaction substrates were primary or secondary alkylic amines, as well as one aromatic amine. Nineteen phosphoramidates could be obtained (7 of which were not described in the literature) at 50 °C and reaction times of 24 or 48h with reaction yields of 35-99%. 31P and 125Te NMR experiments indicated the in situ formation of a tellurophosphonate intermediate.