Novel chiral N-propargylphosphonamidate monomers (HC CCH2NHP (=O)R-O-menthyl, 1: R = CH3, 2: R = C2H5, 3: R = n-C3H7, 4: R = Ph) were synthesized by the reaction of the corresponding phosphonic dichlorides with menthol and propargylamine. Pairs of diastereomeric monomers 1-4 with different ratios were obtained due to the chiral P-center and menthyl group. One diastereomer could be separated from another one in the cases of monomers 1 and 2. Polymerization of 1-4 with (nbd)Rh+[eta(6)-C6H5B-(C6H5)(3)] as a catalyst in CHCl3 gave the polymers with number-average molecular weights ranging from 5000 to 12,000 in 65-85%. Poly(1)poly(4) exhibited quantitative cis contents, and much larger specific rotations than 14 did in CHCl3. The polymers showed an intense Cotton effect around 325 nm based on the conjugated polyacetylene backbone. It was indicated that the polymers took a helical structure with predominantly one-handed screw sense, and intramolecular hydrogen bonding between P=O and N-H of the polymers contributed to the stability of the helical structure. Poly(1a) and poly(2a) decreased the CD intensity upon raising CH3OH content in CHCl3/CH3OH. (c) 2006 Wiley Periodicals, Inc.