Synthesis, resolution and absolute configuration determination of (S)- and (R)-4-formyl-5-hydroxy [2.2]paracyclophane and its application in the asymmetric synthesis of α-amino acids

A chiral photochromic Schiff base: (R)-4-methoxy-2-[(1-phenylethyl)iminomethyl]phenol

“…As for the methoxy group, the O2-C4 and O2 -C16 bond distaces are 1.374 (3) and 1.422 (3) Å, respectively, and the C4-O2-C16 bond angle is 116.9 (2)°. Beside them, geometric parameters reported here agree with corresponding values reported for analogous Schiff base compounds containing the 1-phenylethylamine group (Antonov et al, 1995;Liu et al, 1997). The planarity of (I) is stabilized by an intramolecular O-H•••N hydrogen bond (Table 1).…”

“…For chiral metal complexes and their hybrid materials, see: Akitsu (2007); , 2005a,b, 2006a; Akitsu et al (2009); Yamada (1999). For structral comparison of the 1phenylethylamine moiety, see: Antonov et al (1995); Liu et al (1997). For related Schiff base ligands and their functions, see: ; Akitsu & Einaga (2006b); Hadjoudis et al (1987Hadjoudis et al ( , 2004; Santoni & Rehder (2004); Sliwa et al (2005).…”

Synthesis of novel planar-chiral [2.2]paracyclophane derivatives as potential ligands for asymmetric catalysis

“…Only the use of the amidine base DBU (1,8-diazabicyclo[5.4.0]undecen-7-ene) gave trifluoromethanesulfonic acid- (5-acetyl-[2.2]paracyclophane-4-yl)ester in 25% yield (entry 9). To yield the corresponding imines, two approaches were possible: conversion of the literature known hydroxy-imines [12] to the triflates or condensation of the above synthesized triflates with a-chiral amines. For the AHPC-or BHPC-derived ketimines, the former was the method of choice (Scheme 1).…”

(R)-(–)-[1-(1-Naphthyl)ethyl]salicylaldimine

“…The burgeoning field of asymmetric synthesis relies mainly on the use of chiral ligands for transition metal-based catalysis. Metal complexes of chiral Schiff bases derived from salicylaldehyde and chiral amines have been used successfully for a myriad of reactions, including asymmetric cyclopropanation, oxidation of sulfides, epoxidation of olefins and silylcyanation of aldehydes (Antonov et al, 1995).…”