The chemistry of carbonlum Ion stabilized by means of an acprouriately located'it-bond or, in some cases, of a c-bond has been remarkably advanced(l).
The observed strong C+-'ilinteractlon suuaests that If an unconjuqated diene is treated wlth catlonic rea.qent, transannular cyclizatlon should take place.
Cls, cls-1,5-cyclooctadlene seems to be a very favorable unconjugated diene for cationlc z-it (concerted) or C+ -K (stepwelse) cyclization since l-and 5-double bond are parallel with only a small anale of Pz axis (39.5') and ca. l.il! C-C bond distance apart so that overlau of 7L-orbitals seems to be very effective.
And yet, a little is known on the cationic addition-cycllzatlon of 1,5-cyclooctadiene (COD)(2), although radical addition to COD was investigated somewhat
In detail where a transannular cyclization (Cn-2) DrodUCtS were obtained in fairly good yield(3).
In this communication, the authors describe the stereochemistry of addition of methoxymethyl acetate or other dlsubstltuted methanes on COD in the presence of boron trlfluoride catalyst.
Products are shown In scheme 1.