Search

The complexation reactions of monoaryl- and diaryl-substituted [2.2]paracyclophanes with (NH3)3Cr(CO)3 have been studied. The aromatic rings of [2.2]paracyclophane are more favorable for coordination than aryl substituents. This leads to the regioselective formation of the corresponding mono- or binuclear tricarbonylchromium complexes. In some cases, the tricarbonylchromium group is coordinated to the aryl ring of the substituent to form (in low yields) the corresponding mononuclear complex or binuclear complexes with both the aromatic ring of paracyclophane and the aryl ring of the substituent involved in coordination. The structure of such complex, namely, [4-(η6-2,4,6-trimethylpheny)-11-16-η6-[2,2]paracyclophane]bis[tricarbonylchromium(0)] was confirmed by X-ray diffraction study.

The cross-coupling reactions of 4-bromo[2.2]paracyclophane withp-tolylmagnesium bromide in the presence of various palladium and nickel complexes have been studied. It was found that [1,1 ′-bis(diphenylphosphinoferrocene)]palladium dichloride (PdCl2 · dppf) shows the highest catalitic activity in this reaction. A series of new mono- and diaryl [2.2]paracyclophane derivatives with various substituents in the arene ring have been synthesized using this catalyst. It was shown that it is possible to cross-couple organozinc [2.2]paracyclophane derivatives with aromatic bromides. The composition and structure of the compounds obtained have been established on the basis of elemental analysis and spectral data. Some correlations between the structure and spectral parameters of mono- and diarylsubstituted [2.2]paracyclophanes have been found.

From the reaction mixtures in the uncatalyzed polybromination of [2.2]paracyclophane by the action of excess Br2 in CCl4, there have been found along with the known products — 4,15- and 4,16-dibromo[2.2]paracyclophanes — two new aromatic tribromides of this series, which have been isolated in pure form: 4,12,15- and 4,15,16-tribromo[2.2]paracyclophanes. Special experiments demonstrated that the mixtures of these tribromides are formed as a result of competitive monobromination of 4,15-dibromo[2.2]paracyclophane; the 4,15,16-tribromo[2.2]paracyclophane, together with still another newly isolated isomer of this series — 4,8,12-tribromo[2.2]paracyclophane — is formed as a result of competitive monobromination of 4,16-dibromo[2.2]paracyclophane. As an explanation of the features of the orienting effect of substituents in these competing reactions, a rule was proposed: On the conventional orientation (from the electronic point of view) of entry of the bromine atom into the substituted ring (para > ortho > meta), a steric limitation is imposed on its attack in the pseudo-gem-position, owing to the bulky bromine atom that is transannularly positioned above it in the neighboring aromatic ring. The structures of all of the tribromides were established on the basis of elemental analyses, mass spectrometry, and1H NMR spectrometry (including PMR using the homonuclear Overhauser effect). The data obtained in this work indicate that the 4,12,15-tribromo[2.2]paracyclophane and 4,15,16-tribromo[2.2]paracyclophane are predecessors of the two tetrabromides previously obtained by Cram — 4,7,12,15- and 4,5,15,16-tetrabromo[2.2]paracyclophanes; and the 4,8,12-tribromo[2.2]paracyclophane is a possible predecessor of 4,8,12,16-tetrabromo[2.2]paracyclophane, which is unknown up to the present time.

The cross-coupling reactions of 4-bromo[2.2]paracyclophane withp-tolylmagnesium bromide in the presence of various palladium and nickel complexes have been studied. It was found that [1,1 ′-bis(diphenylphosphinoferrocene)]palladium dichloride (PdCl2 · dppf) shows the highest catalitic activity in this reaction. A series of new mono- and diaryl [2.2]paracyclophane derivatives with various substituents in the arene ring have been synthesized using this catalyst. It was shown that it is possible to cross-couple organozinc [2.2]paracyclophane derivatives with aromatic bromides. The composition and structure of the compounds obtained have been established on the basis of elemental analysis and spectral data. Some correlations between the structure and spectral parameters of mono- and diarylsubstituted [2.2]paracyclophanes have been found.

From the reaction mixtures in the uncatalyzed polybromination of [2.2]paracyclophane by the action of excess Br2 in CCl4, there have been found along with the known products — 4,15- and 4,16-dibromo[2.2]paracyclophanes — two new aromatic tribromides of this series, which have been isolated in pure form: 4,12,15- and 4,15,16-tribromo[2.2]paracyclophanes. Special experiments demonstrated that the mixtures of these tribromides are formed as a result of competitive monobromination of 4,15-dibromo[2.2]paracyclophane; the 4,15,16-tribromo[2.2]paracyclophane, together with still another newly isolated isomer of this series — 4,8,12-tribromo[2.2]paracyclophane — is formed as a result of competitive monobromination of 4,16-dibromo[2.2]paracyclophane. As an explanation of the features of the orienting effect of substituents in these competing reactions, a rule was proposed: On the conventional orientation (from the electronic point of view) of entry of the bromine atom into the substituted ring (para > ortho > meta), a steric limitation is imposed on its attack in the pseudo-gem-position, owing to the bulky bromine atom that is transannularly positioned above it in the neighboring aromatic ring. The structures of all of the tribromides were established on the basis of elemental analyses, mass spectrometry, and1H NMR spectrometry (including PMR using the homonuclear Overhauser effect). The data obtained in this work indicate that the 4,12,15-tribromo[2.2]paracyclophane and 4,15,16-tribromo[2.2]paracyclophane are predecessors of the two tetrabromides previously obtained by Cram — 4,7,12,15- and 4,5,15,16-tetrabromo[2.2]paracyclophanes; and the 4,8,12-tribromo[2.2]paracyclophane is a possible predecessor of 4,8,12,16-tetrabromo[2.2]paracyclophane, which is unknown up to the present time.

1. Depending on the size of the alkyl groups, the reaction of tetraphenylphosphonium chloride with a lithium dialkylamide can proceed in two directions to give 9-phenyl-9-phosphafluorene (I) and benzene, or triphenylphosphine and the dialkylaniline. 2. Lithium monoalkylamides react with tetraphenylphosphonium chloride to give (also depending on the size of the substituents) either N-alkyltriphenylphosphines or phosphine (I). 3. A general scheme was proposed for these reactions, which specifies the formation of the charge-transfer complex or pentacovalent phosphorus compounds.

1. 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 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.

1. Depending on the size of the alkyl groups, the reaction of tetraphenylphosphonium chloride with a lithium dialkylamide can proceed in two directions to give 9-phenyl-9-phosphafluorene (I) and benzene, or triphenylphosphine and the dialkylaniline. 2. Lithium monoalkylamides react with tetraphenylphosphonium chloride to give (also depending on the size of the substituents) either N-alkyltriphenylphosphines or phosphine (I). 3. A general scheme was proposed for these reactions, which specifies the formation of the charge-transfer complex or pentacovalent phosphorus compounds.

1. 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.