Synthetic strategies to inherently chiral calix[4]arenes with mixed ligating functionalities at the lower rim
摘要:
The syntheses of 19 atropisomeric inherently chiral calix[4]arenes derived from syn-proximal (1,2)-bis[(2-pyridylmethyl)oxy]calix[4]arene 2 and mixed syn-distal (1,3)-[(2-pyridylmethyl)oxy][(2-quinolylmethyl)oxy]calix[4] arene 6 are described. Treatment of 2 with 1 equiv of electrophile RX in DMF in the presence of Cs2CO3 afforded racemic tri-O-alkylated cone conformers 3a-k (A(alpha)A(alpha)B(alpha)C(alpha) type), while with an excess of alkylating agent under analogous conditions the chiral tetra-O-alkylated partial cone conformers 4a-d (A(alpha)A(alpha)B(alpha)B(beta) type) were formed. Similarly, exhaustive alkylation of 6 with either PicCl.HCl or QuinCl.HCl gave the chiral partial cone derivatives 7a,b (A(alpha)A(alpha)A(beta)B(alpha) type), respectively. Further alkylation of 3i (R=benzyl) with PicCl.HCl and Cs2CO3 provided partial cone derivative 7c (A(alpha)A(alpha)A(beta)B(alpha) type), while with PrBr and NaH cone tetraether 8 (A(alpha)A(alpha)B(alpha)C(alpha) type) was obtained. Proton and carbon NMR spectral features of these compounds are discussed. Atropisomerism in tri-O-alkylated calix[U arenes was demonstrated by dynamic NMR studies on the less encumbered allyl derivative 3a, which showed no hint for conformational inversion up to 375 K. 2D COSY spectra clearly show that in partial cone structures 4d and 7a-c the N-heteroaryl pendant group of the rotated aryl moiety lies in, and effectively fills, the calix cavity produced by the remaining three aryl rings, The structure of the trisubstituted racemic calix[4]arene 3i has been determined by X-ray crystallography. The molecule adopts a distorted cone conformation with the two pendant pyridinyl groups in the syn-proximal arrangement on one side of the pendant benzyl moiety. There is an intramolecular O-H...O hydrogen bond between the phenolic oxygen OD and the proximal ethereal oxygen OA (to which is bonded the benzyl residue) with O...O 2.85 Angstrom.
Exhaustive alkylation of syn-proximalbis[(2-pyridylmethyl)oxy]calix[4]arene 1 with t-butyl bromoacetate or 2-(chloromethyl)quinoline hydrochloride in the presence of Cs2CO3 affords selectively a new type of inherently chiral calix[4]arenes 2a,b in the partial cone conformation. (±) 2b has been resolved into its optical antipodes by an HPLC method.
在Cs 2 CO 3存在下用溴乙酸叔丁酯或2-(氯甲基)喹啉盐酸盐将近邻双[(2-吡啶基甲基)氧基]杯[4]芳烃1进行彻底的烷基化,选择性地提供了一种新型的固有手性杯[4]芳烃2a,b处于部分圆锥构象。(±)2b已通过HPLC方法拆分为其旋光对映体。
Ferguson George, Gallagher John F., Giunta Luigi, Neri Placido, Pappalard+, J. org. Chem, 59 (1994) N 1, S 42-53
作者:Ferguson George, Gallagher John F., Giunta Luigi, Neri Placido, Pappalard+
DOI:——
日期:——
Synthetic strategies to inherently chiral calix[4]arenes with mixed ligating functionalities at the lower rim
作者:George Ferguson、John F. Gallagher、Luigi Giunta、Placido Neri、Sebastiano Pappalardo、Melchiorre Parisi
DOI:10.1021/jo00080a010
日期:1994.1
The syntheses of 19 atropisomeric inherently chiral calix[4]arenes derived from syn-proximal (1,2)-bis[(2-pyridylmethyl)oxy]calix[4]arene 2 and mixed syn-distal (1,3)-[(2-pyridylmethyl)oxy][(2-quinolylmethyl)oxy]calix[4] arene 6 are described. Treatment of 2 with 1 equiv of electrophile RX in DMF in the presence of Cs2CO3 afforded racemic tri-O-alkylated cone conformers 3a-k (A(alpha)A(alpha)B(alpha)C(alpha) type), while with an excess of alkylating agent under analogous conditions the chiral tetra-O-alkylated partial cone conformers 4a-d (A(alpha)A(alpha)B(alpha)B(beta) type) were formed. Similarly, exhaustive alkylation of 6 with either PicCl.HCl or QuinCl.HCl gave the chiral partial cone derivatives 7a,b (A(alpha)A(alpha)A(beta)B(alpha) type), respectively. Further alkylation of 3i (R=benzyl) with PicCl.HCl and Cs2CO3 provided partial cone derivative 7c (A(alpha)A(alpha)A(beta)B(alpha) type), while with PrBr and NaH cone tetraether 8 (A(alpha)A(alpha)B(alpha)C(alpha) type) was obtained. Proton and carbon NMR spectral features of these compounds are discussed. Atropisomerism in tri-O-alkylated calix[U arenes was demonstrated by dynamic NMR studies on the less encumbered allyl derivative 3a, which showed no hint for conformational inversion up to 375 K. 2D COSY spectra clearly show that in partial cone structures 4d and 7a-c the N-heteroaryl pendant group of the rotated aryl moiety lies in, and effectively fills, the calix cavity produced by the remaining three aryl rings, The structure of the trisubstituted racemic calix[4]arene 3i has been determined by X-ray crystallography. The molecule adopts a distorted cone conformation with the two pendant pyridinyl groups in the syn-proximal arrangement on one side of the pendant benzyl moiety. There is an intramolecular O-H...O hydrogen bond between the phenolic oxygen OD and the proximal ethereal oxygen OA (to which is bonded the benzyl residue) with O...O 2.85 Angstrom.