A new approach to 4-pentynones through palladium-catalysed coupling reaction of the ready available 2-propynyl ketones with aryl iodides and/or vinyl triflates is proposed. Annulation reactions of both 2-propynyl ketones and 4-pentynones gave functionalised furans using potassium tert-butoxide in DMF and functionalised pyrroles in the presence of benzylamine or ammonia, respectively in good to high yields. The methodology has been extended to the preparation of 17 beta-hydroxyandrost-4-en[3,2-b](5-methyl)furan and to 17 beta-hydroxyandrost-4-en[3.2-b](1-benzyl-5-methyl)pyrrole. A different reaction pattern was observed when the 4-pentynones were treated with sodium methoxide in MeOH. The influence of the reaction medium on the outcome of the annulation reaction in the case of one 2-pentyn-1,6-dione (heteroannulation vs. carbocyclization) is also shown. (C) 1998 Published by Elsevier Science Ltd. Ail rights reserved.
Synthesis of functionalised furans and pyrroles through annulation reactions of 4-pentynones / A. Arcadi, E. Rossi. - In: TETRAHEDRON. - ISSN 0040-4020. - 54:50(1998), pp. 15253-15272.
|Titolo:||Synthesis of functionalised furans and pyrroles through annulation reactions of 4-pentynones|
ROSSI, ELISABETTA (Ultimo)
|Parole Chiave:||heterocycles ; palladium ; domino reactions ; furans ; pyrroles|
|Settore Scientifico Disciplinare:||Settore CHIM/06 - Chimica Organica|
|Data di pubblicazione:||1998|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1016/S0040-4020(98)00953-3|
|Appare nelle tipologie:||01 - Articolo su periodico|