New chiral stationary phases based on (R)-1-naphthylethylamine bound to 2,4,5,6-tetrachloro-1,3-dicyanobenzene

Abstract

Chiral functionalization of 2,4,5,6‐tetrachloro‐1,3‐dicyanobenzene (1) by regioselective nucleophilic substitution of one or two chlorine atoms by optically pure (R)‐(+)‐1‐naphthylethylamine (NEA), or by a glycine unit as a spacer to (R)‐NEA, enables the preparation of brush‐type chiral selectors (2, 3, 9, 13). By the introduction of the 3‐aminopropyltriethoxysilyl (APTES) group, reactive intermediates 4a/b, 5, 10a/b, and 14a/b are obtained (a/b indicate a mixture of regioisomers with APTES in 6‐ and 2‐position). Binding of these to silica gel afforded four novel chiral stationary phases (CSPs) 6, 7, 15, and 16. HPLC columns containing CSPs with (R)‐NEA directly linked to polysubstituted aromatic ring (6, 7) are not very effective in resolution of most of the 23 racemic analytes, whereas the columns with distant π‐basic subunits (15, 16) exhibited higher resolving efficacy, in particular towards the isopropyl esters of racemic N‐3,5‐dinitrobenzoyl‐α‐amino acids. Effective resolution of test racemates reveals the importance of the presence of the hydrogen bond donor amido group and the distance between the persubstituted benzene ring in 1 and the π‐basic naphthalene ring of (R)‐NEA. Chirality 11:722–730, 1999. © 1999 Wiley‐Liss, Inc.

Preparation and Studies of Chiral Stationary Phases Containing Enantiopure Acridino‐18‐Crown‐6 Ether Selectors

“…Primary amines are formed during the degradation of amino acids or serve as neurotransmitters . 1‐NEA has several applications: it is often applied as a chiral auxiliary in purification, and it can also be used as a building block of a chiral stationary phase . Furthermore, its derivatives also possess antiarrhythmic and local anesthetic activities .…”

“…18 1-NEA has several applications: it is often applied as a chiral auxiliary in purification, 19 and it can also be used as a building block of a chiral stationary phase. 20 Furthermore, its derivatives also possess antiarrhythmic and local anesthetic activities. 21 One of the main factors, which determines the enantiomeric separation ability of these crown ethers, the π-π interaction, can be enhanced by incorporating a heterocyclic unit containing a more extended aromatic system into the macroring, for example, an acridine unit.…”

Preparation and evaluation of biselector bonded‐type multifunctional chiral stationary phase based on dialdehyde cellulose and 6‐monodeoxy‐6‐monoamino‐β‐cyclodextrine derivatives

“…In general, bonded‐type CSPs have good solvent resistance but show poor enantioseparation ability compared with coated‐type CSPs. To enhance the chiral resolution ability and broaden the scope of chiral recognition, several biselector bonded‐type CSPs have been developed . Chen et al prapared biselector bonded‐type CSP derived from two D‐tartrates, which showed enhanced enantioseparation ability compared with single selector CSPs .…”

“…To enhance the chiral resolution ability and broaden the scope of chiral recognition, several biselector bonded-type CSPs have been developed. [25][26][27][28] Chen et al prapared biselector bonded-type CSP derived from two D-tartrates, which showed enhanced enantioseparation ability compared with single selector CSPs. 29 Wei et al prepared a biselector bonded-type CSP and proved that its enantioseparation ability was relatively lower than that of single selector CSP.…”

Solid‐phase synthesis of chiral stationary phases based on 2,4,5,6‐tetrachloro‐1,3‐dicyanobenzene derivatives spaced from N‐3,5‐dinitrobenzoyl α‐amino acids: Comparative study of their resolution efficacy

“…CSPs II comprise (R)-1-naphthylethyl-amine as the chiral unit in the terminal position, bound directly to, or spaced by, the glycine amido unit from TC-DCB. 10 In CSPs III and IV the chirality resides in the incorporated ␣-AA unit. In CSPs III this unit connects the ␥-aminopropyl silica, 11 whereas in CSPs IV the amide derivatives of ␣-AA's and APTES are bound to the persubstituted aromatic ring in 2,4 or 4,6-position.…”