Propellanes 100. The Nature of the Stereoelectronic Effect in the Highly Stereospecific Hydroxyl Elimination from syn, anti‐[4.3.3]Propellane‐8,11‐diol upon Isobutane Chemical Ionization

A stereospecific 18O‐labelling study shows that the syn‐hydroxy group is preferentially lost from the syn, anti‐title diol upon i‐C4H10 chemical ionization, indicating occurrence of a stereoelectronic effect in this process. A collision‐induced dissociation study of deuterium‐ and 18O‐labelled analogs shows that a symmetrical ether structure is not formed in the above process by an SNi mechanism. This result leads to the conclusion that the stereoelectronic assistance of the anti‐OH group in the loss of the syn‐hydroxyl is expressed either in a weak transition state interaction or by other processes such as β‐elimination via hydrogen transfer with concomitant double bond formation.