Aryllithium reagents are key intermediates in the synthesis of a vast number of substances. The prep — Organic Chemistry Chemistry Question
Where is lithium?
Aryllithium reagents are key intermediates in the synthesis of a vast number of substances. The preparation of such reagents can be achieved by the reaction of aryl halides with lithium or butyllithium. Another possibility involves an acid-base reaction of aromatic/heteroaromatic compounds with a strong base.
[VISUAL]
The reaction of substituted iodobenzene 4 with lithium diisopropylamide (LDA) is an example of an aromatic carboxylic acid synthesis via an acid-base reaction known as the halogen dance reaction. In this case, the reaction affords acid 6 as the major product along with trace amount of acid 5.
[VISUAL]
Draw the mechanism for the reaction of general aryl halide 1 with lithium.
Model Answer
The formation of organolithium reagents involves a radical pathway.
[VISUAL]
Draw the structures of intermediates A, B, C, and D that explain the mechanism of formation of acids 5 and 6.
Model Answer
The structures of intermediates A, B, C, and D:
[VISUAL]
Acid 5 can be prepared by the so-called haloform reaction. Suggest a synthetic route from substrate E (C8H3F3I2O) with suitable reagents.
Model Answer
[VISUAL]
Other reagents, such as NaOH + I2 or NaClO can also be used.