Regio- and stereochemical studies on the nitroso-Diels-Alder reaction with 1,2-disubstituted dienes
Gilles Galvani1, Robert Lett, Cyrille Kouklovsky
1Institut de Chimie Moléculaire et des Matériaux d'Orsay, Bâtiment 410, Université de Paris-Sud, 91405 Orsay (France), Fax: (33) 1-69-15-46-79.
Abstract:
The regioselectivity of the nitroso-Diels-Alder reaction between unsymmetrical acyclic dienes and Boc-nitroso (Boc=tert-butoxycarbonyl) reagent or the Wightman chiral chloronitroso reagents has been studied. With the Boc-nitroso reagent, the selectivity is a consequence of steric effects at the C1-position in the diene and electronic effects at the C2-position in the diene. The combination of an unprotected hydroxyethyl side chain at C1 and an electron-withdrawing group at C2 allows complete regioselectivity in favour of the proximal isomer. The same isomer was obtained exclusively with the chiral nitroso reagent with high enantioselectivities. A model based on steric effects is proposed.
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