INFLUENCE OF MAGNESIUM BROMIDE ON THE REGIOSELECTIVITY OF THE CYCLOADDITION OF YNAMINES WITH CYCLENONES : DIFFERENCE IN REACTIVITY BETWEEN CYCLOHEXENONES AND CYCLOPENTENONES.

Article abstract of DOI:10.1016/0040-4039(81)80134-7

The cycloaddition of ynamines with cyclohexenones occurs in the presence of magnesium bromide at the carbonyl but proceeds by attack on the carbon-carbon double bond without catalyst whereas, in contrast, with cyclopentenones, the reaction takes place at the carbon-carbon double bond with or without magnesium bromide.