García Ruano JL, Fernández-Ibáñez MA, Maestro MC. Efficient trans-Selectivity in the Cyclocondensation of (S)-2-[2-(p-Tolylsulfinyl)phenyl]acetaldehyde with Activated Dienes Catalyzed by Yb(OTf)3.
J Org Chem 2006;
71:7683-9. [PMID:
16995674 DOI:
10.1021/jo061128n]
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Abstract
Reactions of (S)-2-[2-(p-tolylsulfinyl)phenyl]acetaldehyde 1 with Danishefsky's and related dienes took place in the presence of Yb(OTf)3 in a completely stereoselective manner, mediated by a remote sulfinyl group (1,5-asymmetric induction), to afford the corresponding 2,3-dihydro-4H-pyran-4-ones. These reactions followed a stepwise mechanism, as was corroborated by isolation of the corresponding intermediates, with a high level of trans-selectivity for 4-methyl-substituted dienes. Treatment of the adducts with Raney Ni provided concomitant cleavage of the C-S bond and reduction of the conjugated carbonyl grouping.
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