Chiral acyl radical equivalents: 5-exo cyclization of conformationally constrained 1,3-dioxolanyl radicals

✍ Scribed by D. Stien; D. Crich; M.P. Bertrand

• Book ID: 104208786
• Publisher: Elsevier Science
• Year: 1998
• Tongue: French
• Weight: 532 KB
• Volume: 54
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(98)00633-4

✦ Synopsis

Chiral 1,3-dioxolan-2-yl radicals derived from acetals 8 and 9 underwent intramolecular hydrogen abstraction followed by 5-exo-trig cyclization on treatment with tributyltin hydride and AIBN with modest and opposite stereoselectivities. The more highly substituted substrate 13 took part in a similar cascade, triggered by a 5-exo-dig cyclization. In this example the more highly substituted nature of the alkene in the stereocontrolled cyclization resulted in essentially complete diastereoselectivity.