synthesis of a new chiral pyrrolidine合成一种新的手性氮杂戊环.pdfVIP

Molecules 2010, 15, 1501-1512; doi:10.3390/molecule OPEN ACCESS molecules ISSN 1420-3049 /journal/molecules Article Synthesis of a New Chiral Pyrrolidine † Mari Fe. Flores, Marta G. Núñez, Rosalina F. Moro, Narciso M. Garrido, Isidro S. Marcos, Enrique F. Iglesias, Pilar García and David Díez * Departamento de Química Orgánica, Universidad de Salamanca, Plaza de los Caídos 1-5, 37008, Salamanca, Spain † This paper is dedicated to Prof. Pelayo Camps on occasion of his 65th birthday. * Author to whom correspondence should be addressed; E-Mail: ddm@usal.es; Tel.: +34-923-294-474; Fax: +34-923-294-574. Received: 8 December 2009; in revised form: 2 February 2010 / Accepted: 5 March 2010 / Published: 9 March 2010 Abstract: The synthesis of a new chiral pyrrolidine has been performed using 2,3-O-iso- propylidene-D-erythronolactol as a suitable starting material. Keywords: organocatalysis; pyrrolidines; sulfones; nitrones 1. Introduction In the last years there has been a growing interest in organocatalysis [1–6], a new field which has quickly attracted researchers’ attention due to its potential for saving costs, time and energy compared to classic catalysis. Among the many known organocatalysts L-proline is perhaps the one which has been most studied. This fact has led to the appearance of many analogues [7–14]. In the seminal paper of List, Lerner and Barbas III [15], it is described how in the aldol reaction the catalytic activity of L-proline increases using trans-4-hydroxy-L-proline and also how the enantiomeric excess reverses using cis-4-hydroxy