Asymmetric Claisen Rearrangements on Chiral Vinyl Sulfoxides
作者:Roberto Fernández de la Pradilla、Carlos Montero、Mariola Tortosa、Alma Viso
DOI:10.1002/chem.200801680
日期:2009.1.5
Highly diastereoselective Claisen rearrangements of acyclic allyl vinyl ethers bearing a chiralsulfoxide at C‐5 provide γ‐δ‐unsaturated aldehydes or ketones with up to two consecutive asymmetric centers in the molecule whilst preserving a useful vinyl sulfoxide. The reactivity of related vinyl sulfides and sulfones has also been examined in this work.
Nucleophilic reactions with Grignardreagents and the Mukaiyama aldol reactions of the naphthaldehydes having the (2,4, 6-triisopropylphenyl)sulfinyl group produced products with high stereoselectivity. In these reactions, the stereochemistry of the major products changes depending on the Lewis acids used. Reduction of the 2-acyl-1-[(2,4,6-triisopropylphenyl)sulfinyl]naphthalenes also proceeds with
An improvedprocedure of the Sharpless method for the preparation of chiral sulfinates by triphenylphosphine is described. A mixture of sulfonyl chlorides and diacetone-d-glucose or l-menthol in the presence of triethylamine was treated with triphenylphosphine in CH2Cl2 at 0°C to give the sulfinates in good yields.
New chiral sulfoxide ligands which are useful for catalytic asymmetric Diels–Alder reactions have been developed. The newligands involve a chiral sulfinyl function and a 1,3-oxazoline ring with an asymmetric carbon center, in which the chiral sulfinyl group has been revealed to play a crucial role in achieving high enantioselectivity in asymmetric Diels–Alder reactions. Among the Lewis acid catalysts