Rearrangements concerted with fragmentation of cyclopropylmethoxychlorocarbene and cyclobutoxychlorocarbene in hydrocarbon solvents and Ar matrices.
Fragmentations of cyclopropylmethoxychlorocarbene (6) and cyclobutoxychlorocarbene (10) lead to rearrangments that afford mixtures of cyclopropylmethyl chloride (7), cyclobutyl chloride (8), and 3-butenyl chloride (9). Isotopic substitution studies show that these rearrangments are accompanied by partial exchange of the methylene groups within 6 and 10. Surprisingly, these processes that are typical of carbocations persist in hydrocarbon solvents such as pentane and cyclohexane-d(12). Quantum chemical calculations reveal that the cis-conformers of the incipient oxychlorocarbenes C(4)H(7)OC(..)Cl decay to C(4)H(7)Cl + CO via transient hydrogen bonded C(4)H(7)(delta)(+)...Cl(delta-) complexes which possess significant ion pair character, even in the gas phase or in nonpolar solvents. In contrast to benzyloxychlorocarbene, no free radicals are formed upon generation or photolysis of 6 or 10 in Ar matrixes, although acid chlorides (the recombination products of these radical pairs) are observed. The IR spectra obtained in these experiments show the presence of several conformers of the two C(4)H(7)OC(..)Cl.
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
Sauers
Ronald R
RR
Zheng
Fengmei
F
Fu
Xiaolin
X
Bally
Thomas
T
Maltsev
Alexander
A