Nortricyclyl-norbornenyl cation system accessed by carbene fragmentation.
Fragmentation of nortricyclyloxychlorocarbene 5 in pentane occurs by an S(N)i-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 approximately 10% of exo-2-norbornenyl chloride 4g. From exo-2-norbornenyloxychlorocarbene 6 in hydrocarbon solvents, "S(N)i" reactions lead mainly to exo- (4g) and endo-2-chloro-5-norbornenes (4g'). Leakage to ion pairs adds approximately 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.
Moss
Robert A
RA
Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08903, USA. moss@rutchem.rutgers.edu
Ma
Yan
Y
Sauers
Ronald R
RR
Madni
Mahvash
M