Polynucleotide analogues. VI. Synthesis and characterization of alternating copolymers of maleic anhydride and dihydropyran containing guanine derivatives

2-Amino-6-chloropurine was reacted with 2-(tosyloxymethyl)-2,3-dihydro-2H-pyran to give 2-(2-amino-6-chloropurin-9-ylmethyl)-2,3-dihydro-2H-pyran ( 3 ) and its N⁷-isomer ( 4 ), which were treated with 5% aqueous trimethylamine to result in 2-(guanin-9-ylmethyl)-2,3-dihydro-2H-pyran ( 5 ) and its N⁷-isomer ( 6 ), respectively. 2-(N²-Acetylguanin-9-yl-methyl)-3,4-dihydro-2H-pyran ( 7 ) and 2-(N²-acetylguanin-7-ylmethyl)-3,4-dihydro-2H-pyran ( 8 ), obtained by acetylation of compounds 5 and 6 , were copolymerized with maleic anhydride to give the alternating copolymers 9 and 10 , and they were hydrolyzed to result in poly {2-(guanin-9-ylmethyl)tetrahydropyran-5,6-diyl} {1,2-dicarboxyethylene}] ( 11 ) and poly {2-(guanin-7-ylmethyl)tetrahydropyran-5,6-diyl} {1,2-dicarboxyethylene}] ( 12 ), re-spectively. Polymer 11 showed hypochromicity whereas 12 exhibited hyperchromicity in aqueous solutions. Polymers 11 and 12 in aqueous solutions showed very strong excimer fluorescence with the maximum intensities at 432 and 446 nm, respectively, at room tem-perature. The two polymers showed polyelectrolyte effects, e.g., very high GPC molecular weights as well as reduced viscosities at low concentrations in water. Normal behavior was retained by addition of inorganic salts. Sodium salts of polymers 11 and 12 migrated to the anode by electrophoresis and both showed two bands. © 1995 John Wiley & Sons, Inc.