Chiral acyl radical equivalents: 5-exo cyclization of conformationally constrained 1,3-dioxolanyl radicals
1998; Elsevier BV; Volume: 54; Issue: 36 Linguagem: Inglês
10.1016/s0040-4020(98)00633-4
ISSN1464-5416
AutoresDidier Stien, David Crich, M. P. BERTRAND,
Tópico(s)Oxidative Organic Chemistry Reactions
ResumoChiral 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.
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