jo0401218_si_001.pdf (298.17 kB)
Nortricyclyl−Norbornenyl Cation System Accessed by Carbene Fragmentation
journal contribution
posted on 2004-05-28, 00:00 authored by Robert A. Moss, Yan Ma, Ronald R. Sauers, Mahvash MadniFragmentation of nortricyclyloxychlorocarbene 5 in pentane occurs by an SNi-like process which
yields nortricyclyl chloride 3g. In more polar solvents, fragmentation leads to nortricyclyl cation
chloride anion pairs (9) that give mainly 3g, accompanied by ∼10% of exo-2-norbornenyl chloride
4g. From exo-2-norbornenyloxychlorocarbene 6 in hydrocarbon solvents, “SNi” reactions lead mainly
to exo- (4g) and endo-2-chloro-5-norbornenes (4g‘). Leakage to ion pairs adds ∼16% of nortricyclyl
chloride 3g. In more polar solvents, the main product remains chloride 4g, but increasing quantities
of 3g appear due to enhanced participation of ion pairs. Fragmentations of 5 and 6 in MeOH afford
chlorides 3g and 4g as well as the corresponding methyl ethers 3b and 4b. Nortricyclyl cation and
norbornenyl cation chloride anion pairs and methanol-solvated nortricyclyl cations are invoked to
rationalize the results.