Novel isolated, L-amino acid-ligated rhodium catalysts that induce highly helix-sense-selective polymerization of an achiral 3,4,5-trisubstituted phenylacetylene

Abstract

Two novel chiral well‐defined rhodium complexes, Rh(cod)(L‐Phe) (cod = 1,5‐cyclooctadiene, Phe = phenylalanine) and Rh(cod)(L‐Val) (Val = valine) were synthesized, isolated by recrystallization, and characterized. The helix‐sense‐selective polymerization (HSSP) of an achiral 3,4,5‐trisubstituted phenylacetylene, p‐dodecyloxy‐m,m‐dihydroxyphenylacetylene (DoDHPA) was examined by using the two Rh complexes as catalysts. These catalysts provided high molecular weight polymers (Mw 28 × 104−45 × 104) in about 40%–85% yields. The resulting polymers exhibited a bisignated CD signal at about 300 nm and a broad signal around 470 nm, indicating that they have preferential one‐handed helical structure. The present catalysts achieved larger molar ellipticity up to [θ]310 = 13.0 × 104 deg cm2/dmol than those with binary chiral catalytic systems, [Rh(cod)Cl]2/(L‐phenylalaninol), [Rh(cod)Cl]2/(L‐valinol), and [Rh(nbd)Cl]2/(R)‐PEA. All these results manifest that the present, well‐defined Rh complexes serve as excellent catalysts for the HSSP of DoDHPA. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2346–2351

[Rh(L-alaninate)(1,5-Cyclooctadiene)] Catalyzed Helix-Sense-Selective Polymerizations of Achiral Phenylacetylenes

“…Asymmetric catalysis is one of the best methods for the synthesis of optically active organic compounds [1,2]. The design and development of novel catalytic systems for asymmetric synthesis and polymerizations have been active research areas in recent years [3,4,5,6,7,8,9,10]. In particular, in the field of phenylacetylene ( PA ) asymmetric polymerizations, Rh catalysts have been found to play a vital role and cannot be replaced by other metal catalysts [11].…”

The oxidative coupling between benzaldehyde derivatives and phenylacetylene catalyzed by rhodium complexes via C-H bond activation

“…In previous studies, rhodium catalysts have been used in many different domains, such as oxidative coupling reactions [1,2], activated chemical bond reactions [3,4], polymerizations [5,6], and asymmetric hydrogenation reactions [7,8]. Rh complexes have shown high catalytic activity, especially in the case of polymerizations of various substituted acetylenes [9,10,11]. We previously reported two kinds of novel Rh complexes containing l-amino acids and 1,5-cyclooctadiene (cod) as ligands to catalyze the helical selective polymerization of m-dihydroxyphenylacetylene, 3,4,5-trisubstituted phenylacetylene, and p-dodecyloxy-m,m-dihydroxyphenylacetylene [11].…”

“…Rh complexes have shown high catalytic activity, especially in the case of polymerizations of various substituted acetylenes [9,10,11]. We previously reported two kinds of novel Rh complexes containing l-amino acids and 1,5-cyclooctadiene (cod) as ligands to catalyze the helical selective polymerization of m-dihydroxyphenylacetylene, 3,4,5-trisubstituted phenylacetylene, and p-dodecyloxy-m,m-dihydroxyphenylacetylene [11].…”

“…We synthesized Rh(l-amino acid)(cod)s, which are chiral, highly selective and highly active Rh complexes [11]. In this paper, these Rh complexes were used in oxidative coupling reactions between phenylacetylene and benzaldehyde derivatives.…”