Octane, isotopically labelled

The use of isotopically labeled proton donors affords a useful synthesis of labeled compounds. For example, abstraction of a proton from the methyl group of exo-3-acetyl-e do-tricyclo[3.2.1.0 ]octane (5) gave an enolate ion that could abstract a deuterium ion from solvent to produce the monodeuterated compound. Repeated exchange of the methyl protons led to a nearly quantitative yield of trideutero product 6 (Scheme 3.21). 

Photolysis of bicyclo[2.2.2]octan-2-one (A) gives B in good yield. When A labeled as shown is used, the aldehyde group carries deuterium to the extent of 51.7%. Write a mechanism to account for the overall transformation. Calculate the isotope effeet for the step in which hydrogen-atom transfer occurs. What mechanistic conclusion do you... 

Macheroux et al. also examined the deuterium isotope effects of [ 1- H]-labeled octanal and dodecanal by reacting with isolated luciferase Intermediate II.Three kinetic phases were detected, and isotope effects of 1.23 to 1.62 were observed for the second kinetic phase and the parallel Hght decay. Importantly, the first kinetic phase is free from deuterium isotope effect. This optically and kineticaUy definable phase is postulated to correspond to the luciferase flavin-4a-peroxyhemiacetal Intermediate III, detected for the first time in this work. 

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