Enantioselective Synthesis of 1,5-anti- and 1,5-syn-Diols Using a Highly Diastereoselective One-Pot Double Allylboration Reaction Sequence
Eric M. Flamme and William R. Roush*
*Department of Chemistry, University of Michigan, Ann Arbor, Michigan
48109-1055, Email: roush
umich.edu
E. M. Flamme, W. R. Roush, J. Am. Chem. Soc., 2002, 124, 13644-13645.
DOI: 10.1021/ja028055j
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Abstract
Highly diastereo- and enantioselective syntheses of 1,5-disubstituted (E)-1,5-anti-pent-2-endiols and (Z)-1,5-syn-pent-2-endiols have been achieved via the one-pot coupling of two different aldehydes with bifunctional γ-boryl-substituted allylborane reagents, which were generated in situ by the hydroboration of allenes with diisopinocampheylborane. The stereospecificity is discussed.
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Details
The document details a study by Eric M. Flamme and William R. Roush on the enantioselective synthesis of 1,5-anti- and 1,5-syn-diols using a highly diastereoselective one-pot double allylboration reaction sequence. The researchers aimed to develop a method for the diastereo- and enantioselective synthesis of these diols via reactions of two different aldehydes with a chiral, 1,3-bifunctionalized allylmetal reagent. They explored the use of (E)-[(1,3,2-dioxaborinanyl)allyl]diisopinocampheylborane (4) and its reactions with various aldehydes, achieving high diastereoselectivity and enantioselectivity. The study demonstrated that the allylboration of intermediate 5 proceeds with excellent selectivity, providing 1,5-anti-diols with 84-95% ee and 1,5-syn-diols with 91-95% ee. The method's success is attributed to the stereocontrol in the allylboration step and the ability of the diol auxiliary to induce equatorial or axial placement of the R-boryl substituent in the transition states. The research offers a novel approach to synthesizing 1,5-diols with high stereocontrol, which could be applied in natural product synthesis. The study was supported by the National Institutes of Health and further details, including experimental procedures, are available in the supporting information.
Key Words
Hydroboration, Allylic Alcohols, Homoallylic Alcohols
ID: J48-Y2002-1340
