Síntese de derivados de furanos e isocalcogenocromenos via ciclização eletrofílica

Abstract

In this work, a range of (Z)-enynols 4 was prepared from telluroenynes 1 via tellurium-lithium exchange reaction followed by addition of different aldehydes or ketones. Subsequently the substrate 4 was subjected to an electrophilic intramolecular cyclization mediated by palladium salt. This methodology allowed the preparation of functionalized 2,5-dihydrofuran 5 and furan derivates 6, furnishing the corresponding products in good yields. After that, we developed a methodology to obtain isochalcogenchromenes 10 via electrophilic cyclization reaction of 2-alkynylbenzylchalcogenides 9. Using this protocol, a series of 2-alkynylbenzylchalcogenides 9 was prepared by substitution reaction with anions alkylchalcogenolates, followed by Sonogashira cross-couplig reaction. Subsequently, these substrates were cyclized with electrophiles, such as I2, furnishing the correspondent products in moderate to good yields.