Oxidative coupling of carboxylic acid dianions

The synthesis of biologically active indolocarbazole natural products

“…106 The key step in their approach was oxidative coupling of the methyl indol-3-ylacetate dianon to give diester 136 as a mixture of dl and meso forms, which were easily separated by crystallisation and chromatography. [107][108][109] Their initial approach was centred on formation of the indol-3-ylacetate trianion utilising similar chemistry, however it proved more fruitful to proceed via the dianion. The diester 136 was then subjected to imidation with benzylamine before an oxidative cyclisation gave N-benzyl protected arcyriaavin A 37.…”

Stereoselective coupling of ketone and carboxylate enolates

“…4 However, an electron transfer (ET) process appears to be much more likely. [5][6][7] In this case, the enolate 2 is oxidized with iodine by SET to give an initial radical cation which eliminates MI to afford radical 3, which may further react with [I] 2 • to give an a-iodocarbonyl compound 5. This can react with the excess of enolate present in solution by an S N 2 or SET pathway, affording the observed products 4.…”

“…Thus, the oxidative coupling of carboxylic acid dianions was inhibited when the amine arising from enolate generation with Li-amides was present in the reaction medium. 5,12 3 Stereoselective coupling of the enolates of carboxylic acid derivatives One of the key features of the oxidative dimerization reaction of carboxylic acid derivatives is the possibility of achieving a high degree of simple diastereoselectivity (syn+anti ratio). 13 This has been observed in the oxidative dimerization of the Li-dianions of carboxylic acids.…”

Oxidative cross-coupling: an alternative way for C–C bond formations

“…(3) Oxidative coupling of carboxylic acid. The third type oxidative coupling was developed by Belletire et al [10] in 1984. They employed the carboxylic acid compounds as the substrates and successfully achieved the homo-coupling products when lithium diisopropylamide (LDA) completed the hydrogen abstraction and I 2 acted as oxidant (Scheme 1c).…”