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Carbon-13 substituent chemical shifts are reported for a series of 4-substituted bicyclo[2.2.2]octyl acetylenes, benzenes, cyanides, ethylenes, aldehydes, and esters. These shifts, for atoms contained in unsaturated probe linkages, are proportional to substituent field effects ( cF). Unlike fluorine-19 chemical shifts in corresponding bicyclo[ 2.2.2loctyl fluorides, no definitive evidence is found for significant substituent electronegativity effects. This result is confirmed by ab initio molecular orbital calculations on bicyclo[2.2.2]octyl acetylenes and cyanides and some corresponding model systems. Unlike the corresponding aromatic side-chain derivatives, infrared intensity data for stretching absorptions of the unsaturated probes in the bicyclo[2.2.2]octyl compounds do not follow polar substituent effects.The stereochemistry of the intramolecular 1,5 carbon-hydrogen insertion reaction of alkylidenecarbenes to form cyclopentenea has been determined. The isotope effects for two intramolecular examples of insertion reactions of this class of carbenes have been measured, and the dependence upon temperature of one of them has been evaluated. It is concluded that the reaction path is devoid of long-lived intermediates and that its trajectory involves a nonlinear disposition of the carbenic carbon atom and the carbon-hydrogen bond into which insertion occurs.

Gas-phase acidities are reported for series of substituted quinuclidinium and bicyclo [2.2.2] octylammonium ions. A b initio calculations are also reported for these equilibria at the ST03G and 3-216 (for the quinuclidines) bases and can be used to extend the results. pK, values obtained for the bicyclooctylammonium ions are compared with previously reported results for the quinuclidinium ions. The results, as a whole, are considered together with similar values obtained for other saturated systems, to look at the varying transmission of field effects with distance. The falloff observed between the two series in the gas phase is considerably less than expected from simple electrostatics. In contradication with a recent claim, it is also shown that field effects, as measured by the parameter UF, give a good measure of the effect of the substituents in each series compared with a combination of resonance and electronegativity effects.Two additional important series are 4-substituted quinuclidines and bicyclo L2.2.21 octylamines. We report here the experimental AGw values for processes (1) and H I w imental and theoretical results for substituted X

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