179797-06-9Relevant academic research and scientific papers
Utilizing terpene derivatives in the synthesis of annulated terpene-imidazoles with application in the nitroaldol reaction
Kulhanek, Jiri,Bures, Filip,Simon, Petr,Bernd Schweizer
scheme or table, p. 2462 - 2469 (2009/04/11)
Two classes of terpene derivatives (diketones and monoximes) were condensed into annulated terpene-imidazoles using two general methods. Method A, involving the condensation of terpene diketones and aldehydes, gave lower yields than Method B, which employed terpene monoximes and amines. The mechanism of Method B is discussed. Using both methods, overall 11 new imidazole ligands were synthesized and fully characterized. The molecular structures of the side product 16 and intermediate 4b were also characterized by X-ray analysis. Regarding 1a, N-methylation and subsequent ortho-lithiation and quenching with diphenylphosphinechloride were proven. The synthesized ligands were tested in the Henry reaction providing reaction times 24-72 h and enantioselectivities up to 32% especially for the pyridine 2-substituted ligands 1c, 2c, 3b and N,P-ligand 17.
Platinum(II) compounds with enantiomerically pure bis(pinene)-fused bipyridine ligands - Diimine-dichloro complexes and their substitution reactions
Kolp, Brunhilde,Abeln, Dirk,Stoeckli-Evans, Helen,Von Zelewsky, Alexander
, p. 1207 - 1220 (2007/10/03)
The synthesis of chiral square-planar PtII complexes using symmetrical and unsymmetrical bis(pinene)-fused 2,2′-bipyridine is described. The neutral diimine dichloro complexes show a strong deviation of the coordination sphere from planarity if the pinene groups are attached at the 5-and 6-positions of the pyridine rings. However, this distortion does not occur in parallel with the chiral configuration at the diimine ligands. The substitution of the two cis-chloro ligands with diamines to form five-membered chelate rings shows little diastereoselectivity when racemic mixtures of chiral diamines are used. Also, ligands that are prochiral at the ligating centers show little selectivity upon coordination.
Modular pyridine-type P,N-ligands derived from monoterpenes: Application in asymmetric Heck addition
Malkov, Andrei V.,Bella, Marco,Stará, Irena G.,Ko?ovsky, Pavel
, p. 3045 - 3048 (2007/10/03)
Novel (diphenylphosphinophenyl)pyridine ligands (+)-8, (+)-15, (-)-21, and (-)-26 were synthesized from (-)-β-pinene, (+)-3-carene, (+)-2-carene, and (-)-α-pinene, respectively, via Kro?hnke annulation as the key step, and shown to effect ≤88% ee in Heck addition (27→28). Ligands (+)-15 and (-)-21 are quasi-enantiomeric; ligands 8 and 26 can be prepared in both enantiomeric forms from (+)- and (-)-enantiomers of α- and β-pinene, respectively.
