Regioselectivity of intramolecular Diels-Alder

Very recently, Cook and Danishefsky [24] reported an interesting regioselectivity of intramolecular Diels-Alder reactions reversed by the change in the dienophihc moieties from vinyl to allenyl group (Scheme 19). For R = 2-propenyl group, C is bonded to the methyl substituted carbon Cj of the cyclohexadienone ring. For R = 2,3-butadienyl, C is bonded to Cy... 

Like the intermolecular variant, the rate and regioselectivity of intramolecular Diels-Alder reactions may profoundly be affected by the use of Bronsted or Lewis acids. Cycloadditions with these added reagents frequently proceed at significantly lower temperatures, with a corresponding increase in selectivity in cases where the noncatalyzed reactions are only moderately selective. 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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