Bethell

Los Angeles, Calif. Westminster, N.Y. Bethel, Conn. Carpentersvike, Ik. 

D. Bethell and V Gold, Carbonium Ions, An Introduction, Academic Press, London, 1967. 

Other possibilities (e.g., Overhauser effects) exist for the complication of the patterns of polarization predicted by the simple theory. Interesting transienf. splittings have been observed in polarized F-spectra (Bethell et al, 1972a, b). Nevertheless, straightforward application of the simple rules seems to yield reliable conclusions in most cases. Clearly, however, it is unwise to rely on CIDNP results alone in studies of organic reaction mechanisms other information is invariably necessary to ensure that the correct interpretation is chosen from among the several possibilities which CIDNP may suggest. 

A radical pair pathway has been identified for the conversion of 29 into 30 as indicated by the E/A multiplet due to the A2B2 system in the amine side chain at S 2-5-3-0 ppm (Baldwin and Brown, 1969 for CIDNP in the formation of a methylenecyclohexadiene, see Bethell et al., 1972c). The low enhancement factor (5-20) at maximum polarization suggests that a concerted [1,3] sigmatropic rearrangement may occur concurrently. 

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