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Synfacts 2013; 9(1): 0052
DOI: 10.1055/s-0032-1317749
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York

Rhodium-Catalyzed Asymmetric Vinylogous Addition to Vinyldiazoacetates

Rezensent(en):
Mark Lautens
,
Lei Zhang
Smith AG, Davies HM. L * Emory University, Atlanta, USA
Rhodium-Catalyzed Enantioselective Vinylogous Addition of Enol Ethers to Vinyldiazoacetates.

J. Am. Chem. Soc. 2012;
134: 18241-18244
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Publikationsverlauf

Publikationsdatum:
17. Dezember 2012 (online)

 
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Key words

rhodium - vinylogous addition - silyl enol ethers - siloxyvinyldiazoacetate - chiral tetracarboxylate ligands

Significance

A rhodium-catalyzed asymmetric vinylogous addition of silyl enol ethers to siloxy­vinyldiazoacetates is reported. Depending on the sterics of the substituents on the substrate, this method can access cyclopentenones 2 or alkynoates 3 with high yield and excellent enantioselectivity.


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Comment

The use of (Z)-silyl enol ethers is critical in achieving the observed enantioselectivity. In the proposed mechanism, vinylogous adduct 5 can undergo a stereoselective 1,4-silyoxy shift to form 3. Bulkier R1 groups favor the aldol reaction to form formal [3+2] adduct 6, which in one pot, in acid, can afford 2.


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