Phosphorotropic rearrangement in synthesis of asymmetrically-substituted calix[4]arenes

Abstract

Monosodium derivatives of 1,3-bis(diethoxyphosphoryl)calix[4]arenes undergo 0,O-phosphorotropic rearrangement into corresponding 1,2-bis(diethoxyphosphoryl)calix[4]arenes which are useful reagents in the synthesis of asymmetrically substituted calix[4]arenes with AABH-type substitution of the lower rim.

Titanacalixarenes in Homogeneous Catalysis: Synthesis, Conformation and Catalytic Activity in Ethylene Polymerisation

“…A new and easy method to synthesize the 1,2‐diOH‐depleted p ‐ tert ‐butylcalix[4]arene L6 32 was developed (Scheme ). Firstly, the proximal diethyl diphosphate ester precursor P2 was obtained from the distal diethyl diphosphate ester precursor P1 a in quantitative yield by phosphorotropic rearrangement as described by Markovsky et al33 Compound P2 was then used without further purification to obtain L6 (80 % yield) by reductive cleavage of the phosphate groups. 1,2‐Functionalised p ‐ tert ‐butylcalix[4]arene compounds ( L7 and L8 ) have also been prepared by adapting the method described by Narumi et al34 The mono‐OH‐depleted monomethoxy‐ p ‐ tert ‐butylcalix[4]arene ( L9 ) was synthesised according to the method previously described by Fukazawa and co‐workers 35…”

Inherently Chiral Calixarenes: Synthesis and Applications

“…Twoe xamples of acyl migration have been reported, using either ad initrobenzoyl group [12] or aphosphoryl group. [13,14] In both cases the problem is separation of enantiomers, but it still begs the question whether ac hiral acyl group might migrate stereoselectively.…”

“…The term 'family members' is in itself extremelyb road and can be used to described either the overall size of the calixarene (i.e. number of phenolr ings, which can range from [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] or even other classes of the structurally related molecules, such as the aza-, oxa and thiacalixarenes, not that we should forget the resorcinarenes and other structurally similar compounds.A si ft his is not enough,w ithin each family,d ifferent conformers are also possible:f or example Figure 1shows the four possible conformations of calix [4]arene (note:t he number 4r epresents the four phenol rings). It should therefore be very easy to appreciate the sheer broadness of the field of calixarenes and why many books, and even ac onference series have been dedicated to them.…”

Phosphorus-Containing Chiral Macrocycles

“…Phosphorotropic isomerization of the distally substituted diphosphorylcalixarene 76 into proximal isomer 78 proceeds smoothly under the influence of 1 mole of sodium hydride in THF or benzene solution (Scheme 24) [68,69]. Internally chiral calixarenes 79 b, c, d with an AABH substitution type on the lower rim were obtained by following alkylation or acylation of salt 78.…”