Intermolecular Hydrogen Abstraction Reactions Research Articles

ChemInform Abstract: Intermolecular Hydrogen Abstraction Reaction Between Nitrogen Radicals in Purine Rings and Alkyl Ethers: A Highly Selective Method for the Synthesis of N‐9 Alkylated Purine Nucleoside Derivatives.

A highly selective method for the synthesis of N-9 alkylated purine nucleoside derivatives via an intermolecular hydrogen abstraction reaction between nitrogen radicals in purine rings and alkyl ethers was developed. Novel purine nucleoside derivatives were obtained with good to high yields in the presence of (diacetoxyiodo)benzene (DIB) and iodine in one-step reaction.

Intermolecular Hydrogen Abstraction Reaction between Nitrogen Radicals in Purine Rings and Alkyl Ethers: A Highly Selective Method for the Synthesis of N‐9 Alkylated Purine Nucleoside Derivatives

AbstractA highly selective method for the synthesis of N‐9 alkylated purine nucleoside derivatives via an intermolecular hydrogen abstraction reaction between nitrogen radicals in purine rings and alkyl ethers was developed. Novel purine nucleoside derivatives were obtained with good to high yields in the presence of (diacetoxyiodo)benzene (DIB) and iodine in one‐step reaction.

Photochemical reactions of alkoxy-containing-alkyl phenylglyoxylates: remote hydrogen abstraction

A series of alkoxy-containing-alkyl phenylglyoxylates have been synthesized and their photochemical reactions studied. The intention was to probe structural requirements for remote hydrogen abstraction. Products resulting from 1,10- and 1,11-hydrogen abstraction were isolated from the photochemical reactions of 4′-methoxybutyl phenylglyoxylate 3d and 5′-benzyloxypentyl phenylglyoxylate 3h respectively. Products resulting from Norrish Type II and intermolecular hydrogen abstraction reactions were also isolated. Triplet lifetimes of representative compounds were measured by laser flash photolysis.

Reactivity and Efficiency of Singlet- and Triplet-Excited States in Intermolecular Hydrogen Abstraction Reactions

The rate constants for quenching of the singlet- and triplet-excited state of acetone and a cyclic azoalkane by the hydrogen donors tributyltin hydride, 1,4-cyclohexadiene, and 2-propanol have been determined by time-resolved spectroscopy. It is concluded, in variance with previous studies, that singlet-excited states are significantly more reactive than triplet-excited states and that the reactivity difference between the two states of different spin multiplicity increases (i) with decreasing reactivity of the hydrogen donor and (ii) with increasing singlet−triplet energy gap of the excited state. This result is corroborated by semiempirical calculations. The relative efficiency for photoreduction by tributyltin hydride, which was determined by monitoring the formation of tributyltin radicals upon flash photolysis, was found to be four times lower for singlet-excited acetone than for the triplet state. The discrepancy between higher reactivity but lower efficiency in the intermolecular interaction of n,π...

The kinetics of photochemical reactions. Part II. Calculation of kinetic parameters for the intermolecular hydrogen abstraction reactions of the triplet state of carbonyl compounds

By application of a novel method based on the Bond-Energy–Bond-Order method, a series of kinetic parameters for reactions involving hydrogen abstraction by carbonyl triplets have been calculated. In principle the method is only applicable in the gas-phase; however, a good agreement with experiment is generally observed in reactions involving n–π* triplets in non-polar solvents. The possibility of using the method for carbonyl compounds having low lying π–π* triplets is discussed. A series of pre-calculated kinetic parameters are reported in order to allow the fast estimation of rate constants avoiding detailed calculations.