ORBITAL CONTROL OF STEREOCHEMISTRY IN ACID-CATALYSED ADDITION REACTIONS OF ENDO-TRICYCLO2.4>OCT-6-ENE

Article abstract of DOI:10.1016/S0040-4020(01)82440-6

The reaction of endo-tricyclo<3.2.1.0^2.4>oct-6-ene 1 with methanol in the presence of catalytic amounts of toluene-p-sulphonic acid has been shown to give 2-exo- and endo-methoxybicyclo<3.2.1>oct-3-ene (2c) and (2d) and 2-endo-methoxybicyclo<3.2.1>oct-6-ene (13).The formation of 2-exo-methoxybicyclo<3.2.1>oct-3-ene (2c), the major product of reaction, has been probed by deuterium labelling experiments and a series of 6-exo-7-exo-dideuterobicyclo<3.2.1>oct-3-enes synthesised for (2)H, (1)H and (13)C NMR spectral analysis in order unambiguously to determine the stereochemistry of proton attack on endo-tricyclo<3.2.1.0^2.4>oct-6-ene ( 1).The formation of 2-exo-methoxybicyclo<3.2.1>oct-3-ene (2c) has been determined to involve corner protonation of the cyclopropyl moiety and skeletal rearrangement to an allylic cation with a small but measurable memory effect.