Abstract

A novel and convenient approach to functionalized pyrroles is presented, based on Pd-catalyzed oxidative heterocyclization-alkoxycarbonylation of readily available N-Boc-1-amino-3-yn-2-ols. Reactions were carried out in alcoholic solvents at 80-100 °C and under 20 atm (at 25 °C) of a 4:1 mixture of CO-air, in the presence of the PdI2-KI catalytic system (2-5 mol % of PdI2, KI/PdI2 molar ratio = 10). In the case of N-Boc-1-amino-3-yn-2-ols 3, bearing alkyl or aryl substituents, the carbonylation reaction led to a mixture of Boc-protected and N-unsubstituted pyrrole-3-carboxylic esters 4 and 5, respectively. This mixture could be conveniently and quantitatively converted into deprotected pyrrole-3-carboxylic esters 5 by a simple basic treatment. In the case of diastereomeric (3RS,4RS)- and (3RS,4SR)-N-Boc-3-amino-2-methyldec-5-yn-4-ol (syn-3f and anti-3f, respectively, whose relative configuration was determined by X-ray crystallographic analysis), no particular difference was observed in the reactivity of the two diastereomers between them and with respect to the diastereomeric mixture (3S,4S) + (3S,4R).Interestingly, N-Boc-2-alkynyl-1-amino-3-yn-2-ols 6, bearing an additional alkynyl substituent ? to the hydroxyl group, spontaneously underwent N-deprotection under the reaction conditions and regioselective water addition to the alkynyl group at C-3 of the corresponding pyrrole-3-carboxylic ester derivative, thus directly affording highly functionalized pyrrole derivatives 7 in one step.

Autore Pugliese

• Maggi Sabino

Tutti gli autori

• G. Bartolo; L. Veltri ; R. Mancuso ; G. Salerno ; S. Maggi ; B. Aresta

Titolo volume/Rivista

Journal of organic chemistry

Anno di pubblicazione

2012

ISSN

0022-3263

ISBN

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Numero di citazioni Wos

Nessuna citazione

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Numero di citazioni Scopus

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Settori ERC

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Codici ASJC

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