Stereocontrol in Diels-Alder cycloaddition to unsaturated sugars: reactivities of acyclic seven-carbon trans dienophiles dervied from aldopentoles

✍ Scribed by Derek Horton; Dongsoo Koh

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 854 KB
• Volume: 250
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(93)84004-p

✦ Synopsis

Acyclic trans-2,3-unsaturated aldoheptonate derivatives (1-9) obtained from D-aldopentoses by Wittig chain-extension served as dienophiles for a detailed comparative study of their asymmetric Diels-Alder cycloaddition with cyclopentadiene. Cycloaddition under uncatalyzed thermal conditions gave mixtures of the four possible stereoisomeric norbornene adducts. The endo:exo ratios and the diastereofacial selectivities in the formation of the adducts were determined by NMR spectroscopy and by chemical transformations. The quantitative distribution of adducts as a function of stereochemistry of the dienophile is discussed.