168330-97-0Relevant articles and documents
Cyclocopolymerization of α,ω-Dienes with Carbon Monoxide Catalyzed by (R,S)-BINAPHOS-Pd(II)
Nozaki, Kyoko,Sato, Naomasa,Nakamoto, Koji,Takaya, Hidemasa
, p. 659 - 664 (1997)
Cyclocopolymerization of 1,4-pentadiene with carbon monoxide gave polyketone 3 in the presence of a Pd(II) catalyst bearing an unsymmetrical bidentate ligand, (R,S)-BINAPHOS {=(R)-2-(diphenylphosphino)-1.1′-binaphthalen-2′yl (S)-1,1′-binaphthalene-2,2′-diyl phsophite}. In the repeating unit of 3, exclusive formation of a cyclopentanone framework rather than cyclohexanone has been revealed by 13CNMR and IR spectroscopies. A single-unit analog 2 was prepared to identify the structure of 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 different behavior in thermal analysis from that of propene-CO alternating copolymer. 1,5-Hexadiene also afforded the corresponding cyclocopolymer 5. The molar optical rotation of polymer 3 was much lower than that of 5.
Alternating copolymerization of fluoroalkenes with carbon monoxide
Fujita, Tomoyuki,Nakano, Koji,Yamashita, Makoto,Nozaki, Kyoko
, p. 1968 - 1975 (2007/10/03)
The palladium-catalyzed alternating copolymerization of fluoroalkenes, represented as CH2= CH-CH2-CnF2n+1, with CO was performed using (R,S)-BINAPHOS (2e) as a ligand. The CH 2-CnF2n+1 group is the most electronegative substituent ever reported for the copolymerization (Taft's σ* value of 0.90 for CH2CF3). The copolymer obtained from CH 2=CH-CH2-C8F17 (1a) existed as a mixture of polyspiroketal and polyketone, while that from CH2=CH- CH2-C4F9 (1b) was a pure polyspiroketal, as was revealed by infrared and 13C-CP/MAS NMR spectroscopies. The terminal structure of the polymer from 1b was confirmed by MALDI-TOF MS spectrometry. Detailed NMR studies suggested that the much higher reactivity with (R,S)-BINAPHOS (2e) than that with the conventional ligand DPPP (2a) can be attributed to the unique 1,2-insertion of the fluoroalkene into acylpalladium species. The existence of an electronegative substituent on the α-carbon of the palladium center is successfully avoided in the 1,2-insertion mechanism.
Alternating copolymerization of ω-perfluoroalkyl-1-alkenes with carbon monoxide catalyzed by homogeneous and polymer-supported Pd-complexes
Nozaki,Shibahara,Elzner,Hiyama
, p. 593 - 597 (2007/10/03)
Alternating copolymerization of fluorinated olefins (CnF2n + 1)(CH2)mCH=CH2 (1) and carbon monoxide was carried out using cationic Pd(II)-(R,S)-BINAPHOS complexes (2) as catalysts. To obtain polymeric products sufficiently, existence of at least two methylenes in 1 were essential (m ≥ 2). The products thus obtained formed polyspiroketal (4) rather than polyketone (3), the structures being determined by solid- and solution-state NMR and IR analyses. The water contact angle was 108° for a sample of 4f when it was casted on a glass surface from C6F6 solution.
High-pressure NMR studies on the alternating copolymerization of propene with carbon monoxide catalyzed by a palladium(II) complex of an unsymmetrical phosphine-phosphite ligand
Nozaki, Kyoko,Hiyama, Tamejiro,Kacker, Smita,Horváth, István T.
, p. 2031 - 2035 (2008/10/08)
When high-pressure NMR techniques are employed, the following two facts are revealed. (1) The cis/trans isomerization from (SP-4-4)-[Pt(CH3)(CO)(L1)][BAr4] (8a; L1 = (R,S)-BINAPHOS; Ar = 3,5-(CF3)2C6H3) to the more stable SP-4-3 isomer (8b) is faster than CO insertion into either 8a or 8b, the CO insertion being reversible. (2) For the Pd11-L1-catalyzed copolymerization of propene and CO, there exist at least two major resting states, most probably acylpalladium, (SP-4-3)-[Pd(COR)(L2)(L1)][BAr4] (3; L2 = CH3CN, CO), and alkyl-palladium, [Pd{CH2CH(CH3)C(=O)R}(L1)][BAr4] (5a).
Mechanistic aspects of the alternating copolymerization of propene with carbon monoxide catalyzed by Pd(II) complexes of unsymmetrical phosphine - Phosphite ligands
Nozaki, Kyoko,Sato, Naomasa,Tonomura, Yoichi,Yasutomi, Masako,Takaya, Hidemasa,Hiyama, Tamejiro,Matsubara, Toshiaki,Koga, Nobuaki
, p. 12779 - 12795 (2007/10/03)
The reaction steps responsible for the highly enantioselective asymmetric copolymerization of propene with carbon monoxide catalyzed by a cationic Pd(II) complex bearing an unsymmetrical chiral bidentate phosphine- phosphite, (R,S)-BINAPHOS [(R,S)-2-(diphenylphosphino)-1,1'-binaphthalen-2'- yl 1,1'-binaphthalene-2,2'-diyl phosphite = L1], have been studied. Stepwise identification and characterization were carded out for catalyst precursors (SP-4-2)- and (SP-4-3)-Pd(CH3)Cl(L1) (1a and 1b) and (SP-4-3)- [Pd(CH3)(CH3CN)(L1)]·X1 (X1 = B{3,5-(CF3)2C6H3}4) (2), and complexes related to the reaction steps, (SP-4-3)- [Pd(COCH3)(CH3CN)(L1)]·X1 (3), (SP-4-3)- and (SP-4-4)- [Pd{CH2CH(CH3)COCH3}(L1)]·X1 (4a and 4b), (SP-4-3)- [Pd{COCH2CH(CH3)COCH3}(CH3CN)(L1)]·X1 (5), and (SP-4-3)- [Pd{CH2CH(CH3)COCH2CH(CH3)COCH3}(L1]·X1 (6). An X-ray structure of alkyl complex 4a has been obtained. Studies on [Pt(CH3)2(L1)] (8) reveal that the methyl group is more stabilized at a position trans to the phosphine than at the cis position. This is consistent with the structures of 1-6 in which all carbon substituents are trans to the phosphine moiety in their major forms. On the basis of analogous studies using platinum complexes, an isomerization from (SP-4-3)-[Pd(CH3)(CO)(L1)]·X1 (13a) to the (SP-4-4) isomer (13b) is suggested to occur for the CO-insertion process 2 → 3, which results in the activation of the methyl group for the migration to the coordinated CO. Rapid equilibrium was observed between the two isomers 4a and 4b during the CO insertion process to give 5. Theoretical studies have been carded out on the transformation of 3 to 4a and 4b. The B3LYP and MPn calculations indicated that the alkene insertion into the Pd-acyl bond trans to a phosphine is more favorable than that into the Pd-acyl bond trans to a phosphite. The MM3 calculations demonstrated that one specific transition structure is more favorable than the other possible transition structures for the transformation of (SP-4-4)-[Pd(COCH3)(propene)(L1)]·X1 (14b) to 4b. The difference originates from the steric effects of the BINAPHOS ligand, and the results account for high enantio- and regioselectivities experimentally observed. The two key steps, propene insertion into 3 and CO insertion into 4, were monitored by 1H NMR spectroscopy. The activation energies for these two steps were estimated to be 19.0-19.6 kcal/mol at -20 to 0 °C, their difference being insignificant. The living nature of the copolymerization was proved. Some related chiral ligands were examined for the copolymerization. Copolymerization of other olefins with CO was also investigated.
