Functionalized Major-Groove and Minor-Groove Chiral Polybinaphthyls:  Application in the Asymmetric Reaction of Aldehydes with Diethylzinc

Abstract

A series of functionalized and optically active major-groove polybinaphthyls and minor-groove polybinaphthyls have been synthesized by using the Suzuki coupling reaction and have been spectroscopically characterized. The application of these chiral polymers in the asymmetric addition of diethylzinc to aldehydes has been studied. A minor-groove polybinaphthyl is found to be an excellent catalyst for the asymmetric reaction of diethylzinc with a number of aldehydes. The molecular weight and the molecular weight distribution of the polymer have little effects on the catalytic process. The chiral polymer can be easily recovered and reused without loss of catalytic activity as well as enantioselectivity. These rigid and sterically regular chiral polybinaphthyls represent a new generation of enantioselective polymeric catalysts. The reaction of the polybinaphthyls as well as certain monomeric binaphthyl molecules with diethylzinc has been investigated which has provided further information on the novel polymeric catalysts.

Synthesis and properties of chiral helical chromophore-functionalised polybinaphthalenes for second-order nonlinear optical applications

“…The polymer backbone consists of chiral binaphthalene unit, connected with rigid groups, to ensure the chiral, helical conformation [6][7]10]. Hexyl groups were incorporated for solubility reasons and the chromophores were linked to the polymer backbone through the naphthol functions.…”

“…The organic layer was washed with a saturated NaHCO 3 -solution and brine and dried over Fig. 2 ppol I was synthesized according to literature procedure [6], by reaction of 3a [7] and 4 [6]. …”

Asymmetric Catalysis with Helical Polymers

“…This forms a chiral base complex, which is able to initiate the helix-sense-selective anionic polymerization. [15,21] These polymers were used in the palladium-catalyzed enantioselective allylic substitution reaction of 1,3-diphenylprop-2-enyl acetate (27) with dimethylmalonate (Scheme 9).…”

“…[27][28][29] When the 1,2-addition reaction of benzaldehyde with diethylzinc was performed using the major groove polymers www.chemeurj.org 29 and 30, a rather low enantioselectivity was obtained and also considerable amounts of benzylalcohol were found as a side product. [27] Using the minor groove polybinaphthyl 31, high chemo-and enantioselectivities were obtained; by extending the spacer between the binaphthyl units of 32 the selectivity could be further increased up to 98 % ee. [29] This demonstrates the importance of the position of the catalyst in the polymer.…”

Synthesis of a series of soluble main-chain chiral nonracemic poly(alkyl-aryl ketone)

“…To further extend our research in new polymer synthesis, we have developed the strategy of synthesizing main-chain chiral polyketones using palladium catalyzed condensation polymerization. The chirality of the polyketone main chain is achieved by utilizing chiral binaphthyl moiety, which has been previously reported as chiral monomer for other polymer synthesis [31][32][33][34][35][36][37]. The synthesized chiral polyketones have been extensively characterized by 1 H and 13 C NMR, gel permeation chromatography (GPC), polarimeter, UV-Vis spectrometry and circular dichroism (CD).…”