Grignard Cyclization Reaction of Fluorinated N‐Arylimidoyl Chlorides: A Novel and Facile Access to 2‐Fluoroalkyl Indoles.

Abstract

The yields of the title reaction are greatly affected by the electronic effect of the substituent on the benzene ring. Good yields are obtained with imidoyl chlorides bearing no or electron-donating substituents. The utility of the indole products is demonstrated by conversion of indole (IIb) into heterotauxin derivative (III). -(GE, F.; WANG, Z.; WAN, W.; HAO*, J.; Synlett 2007, 3, 447-450; Dep. Chem., Shanghai Univ., Shanghai 201800, Peop. Rep. China; Eng.) -Klein 25-113

Trifluoroacetimidoyl halides: a potent synthetic origin

“…Hao and co-workers established a facile strategy for the assembly of biologically important 2-fluoroalkyl-substituted indoles via the Grignard cyclization reaction of N-[2-(bromoalkyl) phenyl]imidoyl chlorides (Scheme 62). 80 The α-bromination at the benzylic position of N-[2-(alkyl)phenyl]imidoyl chlorides 62-A with N-bromosuccinimide (NBS)/benzoyl peroxide (BPO) yielded 62-B. The Grignard cyclization reaction proceeded well in the presence of magnesium and was greatly influenced by the electronic effect of the substituent group on the benzene ring.…”

An Efficient Approach to 2-CF3-Indoles Based on ortho-Nitrobenzaldehydes

“…Both radical and electrophilic trifluoromethylations was performed using bis(perfluoroalkanoyl) peroxides [ 48 ], difluorodiiodomethane [ 49 ], hypervalent iodine reagents [ 50 , 51 , 52 , 53 ], CF 3 I [ 54 , 55 , 56 , 57 , 58 ], Umemoto’s reagents [ 59 , 60 ], [(phen)CuCF 3 ] [ 61 ], and CF 3 SO 2 Na [ 62 , 63 , 64 , 65 ]. Cyclization approaches are based on formation of C2-C3 bond as a key step and deal with transformations of compounds having ortho -toluidine fragment [ 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 ]. One work reported transformation of 4- and 6-nitro-1-hydroxy indoles to NH indoles under treatment with bromoacetophenone ( Figure 2 ) [ 77 ].…”