N. A. Nesmeyanov

Interaction of lithium alkylamides or lithium dialkylamides with tetraphenylphosphonium chloride reaction course as a function of reaction conditions and dialkylamide structures

Reaction of Ph4P+Cl− with LiNHR (where R = CH3, C2H5, i-C3H7, n-C4H9, but not C(CH3)3) gives phosphineimines III, whereas the reaction with LiNR2 proceeds via three routes depending on the size of R and the dialkylamide excess. With larger R groups, homolytic decomposition of pentacoordinate phosphorus compounds occurs. With smaller R groups, Ph3P and PhNR2 are formed. Higher excesses of lithium amide result, probably, in ligand exchange at the pentacoordinate phosphorus followed by decomposition of the exchange products. Charge transfer complex intermediates are assumed to be formed in all the reactions.

Reaction of allyltriphenylphosphonium iodide with amines

Conclusions1.Allyltriphenylphosphonium iodide rearranges to propenyltriphenylphosphonium: iodide in the presence of tertiary amine.2.Ammonia and primary and secondary amines smoothly add to propenyltriphenylphosphonium iodide to form N-substituted (2-aminopropyl)triphenylphosphonium salts.

Reaction of stable ylids of arsenic with ketones

1. Triphenylarsinobenzoylmethylenes react with cyclohexanone and acetone in harmony with the Wittig reaction. 2. The reaction rates decrease with decrease in the nucleophilicity of the ylids.

Reaction of phosphorylides with diphenyliodonium salts

The reaction between phosphorylides and diphenyliodonium fluoborate leads to the formation of the fluoborates of nonarylated phosphonium salts. An exception is acetylmethylene-triphenylphosphorane, which is arylated at the oxygen of the carbonyl group.

Reaction of stable arsenic ylides with aldehydes

Stable arsenic ylides can be successfully used for the synthesis of olefins according to the Wittig reaction.

Z, E isomerization of alkoxypropenylphosphonium salts by the action of nucleophiles

Conclusions1.Heating Z-triphenyl(2-alkoxyprop-1-enyl)phosphonium iodides with diethylamine and triethylamine leads to their partial geometric isomerization.2.Heating of these salts with alcohols leads to their exchange of the alkoxy group and partially reversible addition of the alcohol at the double bond in addition to isomerization.

Propenyltriphenylarsonium iodide and its reaction with alcohols

Conclusions1.Allyltriphenylarsonium iodide rearranges in the presence of diethylamine or triethylamine to give propenyltriphenylarsonium iodide. The ratio of the starting and rearranged salts is 1:3.2.Alcohols in the presence of sodium alcoholate add to propenyltriphenylarsonium iodide to form (2-alkoxypropyl)triphenylarsonium salts.

Tautomerism of β-dicarbonyl compounds containing a triphenylarsonium group

Conclusion1.The enolization of triphenylarsoniodiacylmethylene salts depends significantly on the basicity of the anion. The enol form is stabilized by the OH⋯X− bond.2.Triphenylarsoniodiacylmethylene salts are less enolized than their phosphorus analogs and their enol forms have identical structure.

Acylation of arsenic β-ketoylides by carboxylic acid halides

Conclusions1.In contrast to the corresponding phosphorus ylide, triphenylarsinebenzoylmethylene is acylated by acyl bromides at two reaction centers: at the O and C atoms. Triphenylarsineacetylmethylene gives only an O-acylation product.2.In contrast to the phosphorus analogs, acyloxyvinylarsonium salts rearrange on heating into the C-acylated analogs.3.During rearrangement of β-substituted benzoyloxyvinyltriphenylarsoriium bromides in the presence of sodium acetate and β-substituted acetoxyvinyltriphenylarsonium bromides in the presence of sodium benzoate, one and the same mixture of diacyl ylides is formed. It was shown that the rearrangement proceeds via the stage of splitting of the acyl group, followed by C-acylation of the ylide formed by an anhydride.

Acylation of arsenic β-ketoylides by trifluoroacetic anhydride

Conclusions1.Ambident arsenicβ-ketoylides are acylated by trifluoroacetic anhydride at the O atom of the carbonyl group to give diacyltriphenylarsinomethylenes.2.In contrast to their phosphorus analogs, the diacyltriphenylarsinomethylenes are cleaved by strong acids with rupture of either the CF3CO-C bond or the As-C bond.