α-Arylation of 2-Arylacetates and Benzofuran-2-one with Tricarbonyl(fluoroarene)chromium Complexes

3 Transition metals in organic synthesis : Part (ii) Stoichiometric applications

“…Liebscher and co-workers have reported the α-arylation of both 2-arylacetates and benzofuran-2-one with fluoroarene-Cr(CO) 3 complexes through nucleophilic displacement of fluoride. 74 For benzofuran-2-one, excellent diastereoselectivity was observed (dr = 85 : 15). Asymmetric catalysis using planar chiral η 6 -arene-Cr(CO) 3 complexes continues to attract attention and the area has been authoritatively reviewed by Gibson.…”

The synthetic challenge of diazonamide A, a macrocyclic indole bis-oxazole marine natural product

“…An alternative solution for the activation of the tyrosine fragment was investigated by Liebscher and co-workers, and relied on the formation of a tricarbonylchromium arene complex to decrease the electron density in the aromatic ring. 59 Such chromium arene complexes are known to undergo facile nucleophilic substitution, providing that they possess a good leaving group such as chloride or fluoride. When the fluoroarene complex 72 was exposed to the enolate of benzofuranone, the 3-arylbenzofuran-2-one 73 was obtained in good yield after decomplexation of the aromatic ring by exposure to the sunlight in the presence of air (Scheme 19).…”

12 Chromium, molybdenum and tungsten

“…58 During the course of synthesis of some natural product fragments with the aid of [(η 6 -fluoroarene)Cr(CO) 3 ], the species, [LCr(CO) 3 ] (L = methyldiarylacetate, α-arylbenzofuranone) were isolated and structurally characterised. 59 Mechanistic aspects of radical aromatic substitution reactions of [(η 6 -chloroarene)Cr(CO) 3 ] have been discussed. 60 There has been a 95 Mo and 13 C solidstate NMR study of [(η 6 -mes)Mo(CO) 3 ] which has also included a relativistic DFT investigation.…”