An effective strategy of P,N-containing macrocycle design

Abstract

An effective strategy of P,N-containing macrocycle design is described, which is based on covalent self-assembly processes in the course of Mannich-type condensations in threecomponent systems: primary phosphine (or secondary diphosphine)-formaldehydediamine with spatially divided functional groups (or primary amine). This approach allowed the authors to obtain various types of macrocyclic phosphines, namely cage cyclophanes with a 1,5-diaza-3,7-diphosphacyclooctane fragment in the basic framework, cyclophanes with linear P,N-containing spacers, P,N-containing corands and the first P,Ncontaining cryptand with four phosphine centers.

New P,N-Containing Cyclophanes with Exocyclic Pyridyl Containing Substituents on Phosphorus Atoms

“…It should be mentioned that the signal of 5 at d P -43.97 ppm was the most intensive one in the 31 P NMR spectrum of the final reaction mixture, but its content was only 48 % of all phosphorus-containing products, so the selectivity of the covalent self-assembly of the macrocycle has decreased in comparison with analogous condensations of primary arylphosphines where the macrocycle contents were 70-80 %. [18,26] The interaction of this diamine with bis(hydroxymethyl) [2-(pyridine-2-yl)ethyl]phosphine under analogous conditions was very slow and less selective. 31 P NMR monitoring of the reaction has shown that at the initial steps of the reaction the main products were probably oligomeric aminomethylphosphines which provided a wide intensive signal at d P -54.9 ppm.…”

“…[25] The data obtained indicate that the structures of cyclophanes 1 and 2 are similar to that of previously described 28-membered cage P,N-containing macrocycles with two diazadiphosphacyclooctane fragments in chairchair conformations with axial lone electron pairs of phosphorus atoms directed inward the macrocyclic cavity. [18,21,25] The treatment of 1 and 2 with the excess of aqueous hydrochloric acid in chloroform leads to the formation of the microcrystalline precipitates of their monohydrochlorides 3 and 4 (Scheme 1) according to the elemental analysis data. …”

“…The precipitate formed was filtered off at -10 --20 °C, washed with cold DMF and twice with acetonitrile and dried at 0.05 torr for 4 h. Yield: 0.090 g (7 % steps like previously described analogous macrocyclizations on the basis of primary aryl-and benzylphosphines. [18,24,25] At the first step (pyridine-2-yl)-or [2-(pyridine-2-yl) ethyl]phosphine have reacted with solid paraformaldehyde at elevated temperature (90-110 °C) to give corresponding bis(hydroxymethyl)organylphoshine. [10] On the second step the obtained diol has interacted with primary aromatic diamine in DMF at 100-110 °C.…”

“…The successful use of this strategy has resulted in the synthesis of a series of 28-38-membered cage macrocyclic tetraphoshines with two diazadiphosphacyclooctane rings and various phane fragments depending on the nature of starting diamines. [18,21,22] The use of available pyridyl-containing primary phosphines, namely (pyridine-2-yl)phosphine [10,23] and [2-(pyridine-2-yl)ethylphosphine [24] in analogous condensations could become a route to the synthesis of functionalized P,N-containing cyclophanes with pyridyl-containing groups on the periphery. In the present paper we describe the synthesis of the first representatives of 28-and 36-membered cage P,N-containing macrocycles with pyridyl-and pyridylethyl substituents on phosphorus atoms on the basis of the covalent selfassembly approach.…”

“…The inclusion of two P-pyridyl substituted diazadiphosphacyclooctane rings into the macrocycle could definite their spatial positions, change their conformational and coordination behavior. In addition the cyclophanes should have internal molecular cavities which are capable to bind various organic substrates, [18][19][20] and this phenomenon could influence on the catalytic and luminescent properties of the metal complexes of the proposed ligands. The approach to the synthesis of this type of cyclophanes has been previously developed for P-aryl, benzyl-and alkyl-substituted compounds and is based on the covalent self-assembly by Mannich-like condensations between primary phosphines, formaldehyde and primary aromatic diamines with spatially divided amine groups.…”