A novel type of optically active helical polymers: Synthesis and characterization of poly(N-propargylureas)

Organocatalytic chiral polymeric nanoparticles for asymmetric aldol reaction

Chiral polymeric particles (CPPs) were studied extensively in recent years due to their importance in pharmaceutical applications. Here, nanosized CPPs were synthesized and applied as catalysts for direct asymmetric aldol reaction. The CPPs were prepared by miniemulsion or inverse miniemulsion based on various chiral amino acid derivatives and characterized by dynamic light scattering and scanning electron microscopy. The nanoparticles with spherical structure between 250 and 400 nm and high chiral surface area were used as catalysts in the aldol reaction at room temperature without additional solvent. l-tryptophan gave the highest enantiomeric excess, >86% with similar catalytic performance four times.

Optically active helical poly(α,β-unsaturated ketone) from anionic polymerization of (S)-3-acrylyl-2,2′- bis(methoxymethoxy)-1,1′-binaphthyl

(S)-3-acrylyl-2,2′-bis(methoxymethoxy)-1,1′-binaphthyl (3a) was synthesized and anionically polymerized using n-BuLi as an initiator. The polymer derived from 3a had a tremendous specific optical rotation [Formula: see text] = −304.2, while that of the monomer 3a is −68.7. Poly-3a was confirmed to exist in the form of a one-handed helical structure in solution by means of comparing the specific optical rotation, the circular dichroism, and UV-vis spectra with that of 3a and the model compounds such as (S)-3-propionyl-2,2′-bis(methoxymethoxy)-1,1′-binaphthyl (3b) and (S)-3-heptanoyl-2,2′-bis(methoxymethoxy)-1,1′-binaphthyl (3c). This conclusion was also confirmed by the fact that the g value of poly-3a is about 15 times of that of the monomer 3a.

Preparation and application of abietic acid-derived optically active helical polymers and their chiral hydrogels

A novel chiral monomer N-propargyl abietamide, M1, was synthesized from abietic acid and catalytically polymerized with (nbd)Rh+B-(C6H5)4 (nbd=norbornadiene), providing polymer [poly(1)] with a molecular weight of 13,000-36,000 at a yield of 59-84%. Poly(1) did not form stable helices in tetrahydrofuran at room temperature whereas copolymerization of M1 and the achiral N-propargylamide monomer, M2, led to the formation of helical optically active copolymers as indicated by circular dichroism studies, UV-vis spectroscopy, and specific optical rotation measurements. Hydrogels were prepared based on an optically active helical copolymer, poly(M1(0.32)-co-M2(0.68)) that exhibited enantioselective recognition toward l-alanine. The novel chiral polymers derived from abietic acid are expected to find applications in such areas as chiral recognition, chiral resolution, and chiral catalysis.