CYCLO-COPOLYMERIZATION OF ALPHA,OMEGA-DIENES WITH CARBON-MONOXIDE CATALYZED BY (R,S)-BINAPHOS-PD(II)

Cyclocopolymerization of 1,4-pentadiene with carbon monoxide gave poly ketone 3 in the presence of a Pd(II) catalyst bearing an unsymmetrical bidentate ligand, (R,S)-BINAPHOS =(R)-2-(diphenylphosphino)-1,1'-bina phthalen-2'-yl (S)-1,1'-binaphthalene-2,2'-diyl phsophite}. In the rep eating unit of 3, exclusive formation of a cyclopentanone framework ra ther than cyclohexanone has been revealed by C-13 NMR and IR spectrosc opies. A single-unit analog 2 was prepared to identify the structure o f 3. In the cyclopentanone unit of 3, the two substituents are cis and trans to each other in almost 1:1 ratio. The polymer 3 showed differe nt behavior in thermal analysis from that of propene-CO alternating co polymer. 1,5-Hexadiene also afforded the corresponding cyclocopolymer 5. The molar optical rotation of polymer 3 was much lower than that of 5.