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Synthesis 2009(7): 1095-1098  
DOI: 10.1055/s-0028-1088008
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

Short and Practical Syntheses of (S)-(+)-3-(p-Tolylsulfinyl)furan-2(5H)-one and (S)-(+)-3-(p-Tolylsulfinyl)-5,6-dihydropyran-2-one

David Cruz Cruza, Angélica Hernández Linaresa, Francisco Yuste*a, M. Rosario Martínb, José Luis García Ruano*b
a Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Cd. Universitaria, Coyoacán 04510, Mexico
Fax: +52(55)56162217; e-Mail: yustef@servidor.unam.mx;
b Departamento de Química Orgánica, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
Fax: +34(914)973966; e-Mail: joseluis.garcia.ruano@uam.es;
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Publication History

Received 7 April 2008
Publication Date:
06 March 2009 (online)

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Abstract

(S)-(+)-3-(p-Tolylsulfinyl)furan-2(5H)-one and (S)-(+)-3-(p-tolylsulfinyl)-5,6-dihydropyran-2-one can be synthesized by a new and significantly improved method consisting of Knoevenagel condensation of benzyl (R)-(+)-(p-tolylsulfinyl)acetate with the tert-butyldimethylsilyl derivatives of 2-hydroxyacetaldehyde or 3-hydroxypropanal, followed by subsequent reactions of the resulting mixtures with hydrogen in the presence of palladium-on-carbon and ethereal hydrogen chloride.

Key words

asymmetric synthesis - chiral auxiliaries - sulfoxides - α,β-unsaturated lactones - butenolides

16

One of the starting products is not commercially available and needs to be prepared by ozonolysis of suitable precursors.

17

The synthesis of (±)-1b (three steps and 25% overall yield) has also been reported; see ref. 8b.

19

5-Hydroxyfuran-2(5H)-one was the only product we could identify when the crude reaction mixture containing 1a was purified by column chromatography.

20

Starting from menthyl p-toluenesulfinate (commercially available in the two possible configurations at sulfur), compounds 1a and 1b are obtained in 41% (30% on 5 mmol scale) and 26% (24% on 8 mmol scale) overall yield, respectively.

21

The ee of (+)-1b was determined from the well-separated p-tolyl signals in the ¹H NMR spectrum by use of tris[3-(hep-tafluoropropylhydroxymethylene)-(+)-camphorato]ytter-bium(III) as chiral shift reagent.