Synthesis 2006(22): 3902-3914  
DOI: 10.1055/s-2006-950310
FEATUREARTICLE
© Georg Thieme Verlag Stuttgart · New York

Phosphorus Ylide Based Functionalizations of Tetronic and Tetramic Acids

Rainer Schobert*, Matthias Dietrich, Gillian Mullen, Juan-Manuel Urbina-Gonzalez
Organic Chemistry Laboratory, University of Bayreuth, Universitaetsstrasse 30, 95440 Bayreuth, Germany
Fax: +49(921)552671; e-Mail: Rainer.Schobert@uni-bayreuth.de;
Further Information

Publication History

Received 30 June 2006
Publication Date:
09 October 2006 (online)

Abstract

The versatility of the ylide (triphenylphosphoranyl­idene)ketene (Ph3P=C=C=O, 3) in the construction of tetronic and tetramic acids from various carboxylic acid derivatives is demonstrated by new reactions and extensions of known ones. With α-hydroxy or α-amino esters, 3 affords tetronates or tetramates. A two-step synthesis of (-)-epi-blastmycinolactol shows that allyl α-hydroxy esters can be domino Wittig-Claisen reacted to give 3-allyltetronic acids. More extended Wittig-Claisen-Conia cascades can produce 3-alkylidenefuran-2,4-diones, the photooxygenation of which furnishes lactone endoperoxides with antiplasmodial potential. Tetronic acids can be acylated by 3 at C3 to give the corresponding acyl ylides. Their saponification yields the respective 3-acetyl compounds, e.g. the fungal metabolite pesthetoxin. α-Hydroxy acids react with 3 to afford the corresponding 3-phosphoranylidenefuran-2,4-diones. The antibiotic (R)-reutericyclin was built up from benzyl d-leucinate and 3 in four steps by downstream acylation first at C3, then at N1 without racemization.

51

According to the WHO protocol (see, http://www.who.int/csr/drugresist/malaria/en/markiii.pdf).

54

Crystallographic data (excluding structure factors) for the structure reported in this paper have been deposited with the Cambridge Crystallographic Data Centre (CCDC number 616240). Copies of the data can be obtained free of charge on application to The Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [fax: +44(1223)336033, e-mail: teched@chemcrys.cam.ac.uk].