Stereochemistry of Addition of the Allyl Grignard Reagent to Hydroxybicyclohept-2-enes

Article abstract of DOI:10.1021/jo01313a004

Reactions of syn-bicyclo<2.2.1>hept-2-en-7-ol with an excess of allylmagnesium chloride in tetrahydrofuran or of allylmagnesium bromide in diethyl ether furnish an addition product shown to be 2-exo-allyl-syn-bicyclo<2.2.1>heptan-7-ol.Reactions of endo-bicyclo<2.2.1>hept-5-en-2-ol with the same reagents and with diallylmagnesium in ether furnish a compound shown to be 5-endo-allyl-endo-bicyclo<2.2.1>heptan-2-ol.A metalated hydroxyl group must play an active role in facilitating these additions since they proceed more rapidly than addition to the parent hydrocarbon,bicyclo<2.2.1>hept-2-ene, which furnishes 2-exo-allylbicyclo<2.2.1>heptane.They must also be considerably more rapid than additions to the epimeric alcohols (anti-bicyclo<2.2.1>hept-2-en-7-ol and exo-bicyclo<2.2.1>hept-5-en-2-ol) since no addition products were obtained from reactions with these alcohols.Attachment of the allyl group to the double bond of each bicycloheptenol from the side nearer the hydroxyl group suggests that at the time of addition the allyl is associated with the metalated hydroxyl group.