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.

Synthesis of functionalised furans and pyrroles through annulation reactions of 4-pentynones

E. Rossi
Ultimo
1998

Abstract

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.
heterocycles ; palladium ; domino reactions ; furans ; pyrroles
Settore CHIM/06 - Chimica Organica
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/183894
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