Stereocontrolled asymmetric synthesis of syn-E-1,4-diol-2-enes using allyl boronates and its application in the total synthesis of solandelactone F

Anna Robinson, Varinder K. Aggarwal*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

20 Citations (Scopus)

Abstract

The solandelactones A-H comprise a novel class of oxygenated fatty acids bearing an eight-membered lactone, trans cyclopropane, and a 2-ene-1,4-diol subunit. The relative stereochemistry of the 1,4-diol subunit is anti in solandelactones A, C, E & G, and syn in solandelactones B, D, F & H. Having prepared one member of the solandelactones bearing anti stereochemistry (solandelactone E), we have targeted the syn series and developed methodology for the synthesis of enantioenriched syn-2-ene-1,4-diols. The methodology comprises asymmetric deprotonation of an alkyl 2,4,6-triisopropylbenzoate using sBuLi/sparteine, followed by addition of the alpha-lithiobenzoate to beta-silyl vinyl boronic acid ethylene glycol ester. The boron-ate complex generated undergoes a 1,2-metallate rearrangement furnishing an intermediate allyl boronic ester which is trapped by an aldehyde in the presence of MgBr2 to furnish anti-beta-hydroxy E-allylsilanes in good yields, high diastereoselectivity and high enantioselectivity. These sensitive products were oxidized using mCPBA to the corresponding epoxides and subsequently treated with acid to furnish syn-E-2-ene-1,4-diols (similar to 4 : 1 d.r.). Application of the methodology to appropriately functionalized aldehyde and.-alkenyl 2,4,6-triisopropylbenzoate coupling partners, led to a short, highly selective route to solandelactone F (bearing a syn-E-2-ene-1,4-diol).

Original languageEnglish
Pages (from-to)1795-1801
Number of pages7
JournalOrganic and Biomolecular Chemistry
Volume10
Issue number9
DOIs
Publication statusPublished - 2012

Keywords

  • HYDROID SOLANDERIA-SECUNDA
  • ENANTIOSELECTIVE SYNTHESIS
  • STEREOSELECTIVE-SYNTHESIS
  • DIASTEREOSELECTIVE SYNTHESIS
  • BORONIC ESTERS
  • ALPHA-HYDROXYALLYLATION
  • ALLYLBORATION REACTIONS
  • HOMOALLYLIC ALCOHOLS
  • CHIRAL CROTYLSILANES
  • MIGRATORY APTITUDES

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