1198791-58-0Relevant articles and documents
α-Propargyl amino acid-derived optically active novel substituted polyacetylenes: Synthesis, secondary structures, and responsiveness to ions
Sogawa, Hiromitsu,Shiotsuki, Masashi,Sanda, Fumio
experimental part, p. 2008 - 2018 (2012/07/13)
Novel optically active substituted acetylenes HCi￡ CCH 2CR1(CO2CH3)NHR2 [(S)-/(R)-1: R1 = H, R2 = Boc, (S)-2: R1 = CH3, R2 = Boc, (S)-3: R1 = H, R2 = Fmoc, (S)-4: R1 = CH3, R2 = Fmoc (Boc = tert-butoxycarbonyl, Fmoc = 9-fluorenylmethoxycarbonyl)] were synthesized from α-propargylglycine and α-propargylalanine, and polymerized with a rhodium catalyst to provide the polymers with number-average molecular weights of 2400-38,900 in good yields. Polarimetric, circular dichroism (CD), and UV-vis spectroscopic analyses indicated that poly[(S)-1], poly[(R)-1], and poly[(S)-4] formed predominantly one-handed helical structures both in polar and nonpolar solvents. Poly[(S)-1a] carrying unprotected carboxy groups was obtained by alkaline hydrolysis of poly[(S)-1], and poly[(S)-4b] carrying unprotected amino groups was obtained by removal of Fmoc groups of poly[(S)-4] using piperidine. Poly[(S)-1a] and poly[(S)-4b] also exhibited clear CD signals, which were different from those of the precursors, poly[(S)-1] and poly[(S)-4]. The solution-state IR measurement revealed the presence of intramolecular hydrogen bonding between the carbamate groups of poly[(S)-1] and poly[(S)-1a]. The plus CD signal of poly[(S)-1a] turned into minus one on addition of alkali hydroxides and tetrabutylammonium fluoride, accompanying the red-shift of λmax. The degree of λmax shift became large as the size of cation of the additive.
