Barton reaction

The Barton reaction, also known as the Barton nitrite ester reaction, is a photochemical reaction that involves the photolysis of an alkyl nitrite to form a δ-nitroso alcohol.

Discovered in 1960, the reaction is named for its discoverer, Nobel laureate Sir Derek Barton. Barton's Nobel Prize in Chemistry in 1969 was awarded for his work on understanding conformations of organic molecules, work which was key to realizing the utility of the Barton Reaction.

The Barton reaction involves a homolytic RO–NO cleavage, followed by δ-hydrogen abstraction, free radical recombination, and tautomerization to form an oxime. Selectivity for the δ-hydrogen is a result of the conformation of the 6-membered radical intermediate. Often, the site of hydrogen atom abstraction can be easily predicted. This allows the regio- and stereo-selective introduction of functionality into complicated molecules with high yield. Due to its unique property at the time to change otherwise inert substrates, Barton used this reaction extensively in the 1960s to create a number of unnatural steroid analogues.

While the Barton reaction has not enjoyed the popularity or widespread use of many other organic reactions, together with the mechanistically similar Hofmann–Löffler reaction it represents one of the first examples of C-H activation chemistry, a field which is now the topic of much frontline research in industrial and academic chemistry circles.