Synthesis 2016; 48(24): 4564-4568
DOI: 10.1055/s-0035-1562625
paper
© Georg Thieme Verlag Stuttgart · New York

A Short Synthesis of the Mould Metabolite (R)-(+)-Carolinic Acid from (S)-Lactic Acid

David Linder
Organisch-chemisches Laboratorium der Universität Bayreuth, Gebäude NW I, 95440 Bayreuth, Germany   Email: Rainer.Schobert@uni-bayreuth.de
,
Rainer Schobert
Organisch-chemisches Laboratorium der Universität Bayreuth, Gebäude NW I, 95440 Bayreuth, Germany   Email: Rainer.Schobert@uni-bayreuth.de
› Author Affiliations
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Publication History

Received: 25 July 2016

Accepted after revision: 27 July 2016

Publication Date:
02 September 2016 (online)


Abstract

(R)-(+)-Carolinic acid was prepared in seven steps and 59% yield from inexpensive benzyl l-lactate, the configuration of which was inverted by a Mitsunobu reaction with trifluoroacetate. The resulting benzyl d-lactate was cyclised by a domino addition–Wittig alkenation reaction with Ph3PCCO. The product tetronic acid was acylated with a second equivalent of this ylide to give a 3-acylylidenetetronic acid, which was olefinated directly with tert-butyl glyoxylate. The product alkene was hydrogenated and deprotected to afford pure crystalline (R)-(+)-carolinic acid, which proved inactive against Staphylococcus aureus and Escherichia coli mutant D21f2.

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