Selective and efficient cycloisomerization of alkynols catalyzed by a new ruthenium complex with a tetradentate nitrogen-phosphorus mixed ligand.
The new ruthenium complex [Ru(N(3)P)(OAc)][BPh(4)] (4), in which N(3)P is the N,P mixed tetradentate ligand N,N-bis[(pyridin-2-yl)methyl]-[2-(diphenylphosphino)phenyl]methanamine was synthesized. The complex was found to be catalytically active for the endo cycloisomerization of alkynols. The catalytic reactions can be used to synthesize five-, six-, and seven-membered endo-cyclic enol ethers in good to excellent yields. A catalytic cycle involving a vinylidene intermediate was proposed for the catalytic reactions. Treatment of complex 4 with PhC[triple bond]CH and H(2)O gave the alkyl complex [Ru(CH(2)Ph)(CO)(N(3)P)][BPh(4)] (30), which supports the assumption that the catalytic reactions involve addition of a hydroxyl group to the C=C bond of vinylidene ligands.
Department of Chemistry, Hong Kong University of Science & Technology Institution, Clear Water Bay, Kowloon, Hong Kong, P. R. China.
Pei Nian
PN
Liu
Fu Hai
FH
Su
Ting Bin
TB
Wen
Herman H-Y
HH
Sung
Ian D
ID
Williams
Guochen
G
Jia
D000480:Alkynes / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D007192:Indenes / Q000737:chemistry*; D007536:Isomerism; D008024:Ligands; D015394:Molecular Structure; D009584:Nitrogen / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010758:Phosphorus / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D014753:Vinyl Compounds / Q000737:chemistry*
D000480:Alkynes; D007192:Indenes; D008024:Ligands; D009942:Organometallic Compounds; D014753:Vinyl Compounds; C545570:vinylindene; D010758:Phosphorus; D012428:Ruthenium; D009584:Nitrogen