Anions rearrangements induced

The alkenyl complexes / 7 r-[Fe(X)(CH=CHC6Hs)(dmpe)2] (X = C1, N3, SCN), which resemble 107, were obtained by a completely different synthetic method. This consists in quantitative anion-induced rearrangement of the hydrido-acetylide complex /ra r-[FeH(C CG6Hs)(dmpe)2] in methanol solution containing chloride, azide, or... 

Based on the above results and the anion-induced rearrangement previously reported by Moss et al./ the following reaction pathway, as illustrated in Scheme 14, is proposed to account for what is happening in the anionic polymerization of... 

Cleavage of a C—S bond in the initially formed anion radical has been shown to be the first chemical step in the electrochemically induced rearrangement of 5,5-diarylbenzene-1,2-dicarbothioates to 3,3-bis(arylthio)phthalides in dimethylformamide. The reaction can be effected with 0.1 F/mol and is considered a kind of internal SRN1 reaction (Praefke et al. 1980). 

Intermolecular transfer of trifluoromethyl has been demonstrated in the fluoride ion induced rearrangement of the perfluorinated alkene (77) to the isomer (78). Again, the driving force in this process is to produce an isomer (78) with fewer vinylic fluorine sites than in the starting isomer (77). The intermediate trifluoromethyl anion has been trapped with perfluoropyrimidine (79)... 

The reaction of 5-silyl-y,5-epoxypentanenitrile derivatives with a base and an alkylating agent gives (Z) - 3 - s i I o x y- y, 3 -u n saturated pentanenitrile derivatives via a tandem process that involves the formation of a cyclopropane derivative by epoxy nitrile cyclization followed by Brook rearrangement and an anion-induced cleavage of the cyclopropane ring (Scheme 105).152... 

Formation of a pentacoordinate 1,2-oxastannetanide by a base-induced rearrangement of a bis(/3-hydroxyalkyl)-stannane has also been reported <1997PS513>. Synthesis of pentacoordinate anionic oxasiletanides, oxagermeta-nides, and oxastannetanides has been reviewed (Scheme 17) <19980M367, 2000JOM256, 2002CSR195>. 

Horne, S., Rodrigo, R. A complex induced proximity effect in the anionic Fries rearrangement of o-iodophenyl benzoates synthesis of dihydro-O-methylsterigmatocystin and other xanthones. J. Org. Chem. 1990, 55,4520-4522. 

The literature offers many more examples of electron transfer induced rearrangements of compounds containing three-membered rings. In general it is not known whether the rearrangement occurs at the radical anion or dianion stage, as is the case in the above-mentioned examples. 

One of the most striking features of the base-induced rearrangement of unsaturated sulfoncs is the high regioselectivity. Both a,/ - and y.d-unsaturated substrates yield the same product via path a. The observed regioselectivity has been explained by the greater stability of a / -oxo sulfone anion compared to a ketone enolate104. 

Retrosynthetic considerations suggested that the obvious inducement for us was the opportunity to transform the known optically pure ketone 82 [49] into 83 in advance of an anionic Cope rearrangement (Scheme XI) [50]. Although 1,2-addition of the cerate prepared from 3-furyllithium proceeded with appropriately high facial selectivity, subsequent isomerization of the potassium salt of 83... 

Compounds containing a l,5-hexadien-3-ol system undergo anionic oxy-Cope rearrangement when treated with the phosphazene superbase Bu-P4. The sigmatropic rearrangement occurs in hexane as well as in THF. The weaker phophazene base Et-P2 failed to induce rearrangement. This is the first example of the use of a metal-free base to induce anionic oxy-Cope rearrangement [49] (Scheme 5.30). 

Scheme Phosphate anion-induced coordination rearrangement of 31 upon binding to a phosphate derivative...

Home S, Rodrigo R (1990) A Complex Induced Proximity Effect in the Anionic Fries Rearrangement of o-Iodophenyl Benzoates Synthesis of Dihydro-O-methylsterigmatocystin and Other Xanthones. J Org Chem 55 4520... 

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