35216-82-1Relevant academic research and scientific papers
Synthesis, Resolution, and Applications of 1,16-Dihydroxytetraphenylene as a Novel Building Block in Molecular Recognition and Assembly
Wen, Jian-Feng,Hong, Wei,Yuan, Ke,Mak, Thomas C. W.,Wong, Henry N. C.
, p. 8918 - 8931 (2003)
This paper concerns the synthesis of 1,16-dihydroxytetraphenylene (DHTP) (2) by employing a novel NBS bromination route. (±)-DHTP 2 was successfully resolved into its optical antipodes and converted to (±)-1,16-bis(diphenylphosphino)tetraphenylene (BPTP) (26), whose platinum complex BPTP-PtCl2 (27) was also obtained. As a hydrogen bond donor, racemic and optically active DHTP 2 was allowed to assemble with 4,4′-bipyridine to form single crystals of good quality. X-ray Diffraction studies of these crystals revealed that the crystallographic packing of the hydrogen bonded complex between (±)-2 and 4,4′-bipyridine was different from the one formed from (S)-2 and 4,4′-bipyridine. It was found that an infinite zigzag chain with alternate chirality was formed in the assembly of (±)-2 and 4,4′-bipyridine, while (S)-2 and 4,4′-bipyridine failed to show the same assembly pattern. The reason (±)-2 formed an alternate and zigzag chain with 4,4′-bipyridine was most likely due to the inherent stability of this supramolecular assembly. The chiral recognition between 2 and optically active BINAP under the direction of platinum(II) has also been examined. 1H and 31P NMR spectroscopic studies demonstrated that there was an obvious discrimination of 2 between the enantiomers of BINAP-PtCO3.
New biphenyl iminium salt catalysts for highly enantioselective asymmetric epoxidation: Role of additional substitution and dihedral angle
Bulman Page, Philip C.,Bartlett, Christopher J.,Chan, Yohan,Allin, Steven M.,McKenzie, Michael J.,Lacour, Jér?me,Jones, Garth A.
, p. 4220 - 4232 (2016/05/24)
New biaryl iminium salt catalysts for enantioselective alkene epoxidation containing additional substitution in the heterocyclic ring are reported. The effects upon conformation and enantioselectivity of this additional substitution, and the influence of dihedral angle in these systems, has been investigated using a synthetic approach supported by density functional theory. Enantioselectivities of up to 97% ee were observed.
New, axially chiral, bimetallic catalysts for asymmetric alkylation of aldehydes with diethylzinc
Keller, Felix,Rippert, Andreas Johannes
, p. 125 - 137 (2007/10/03)
Axially chiral bis(salicylidene)ethylenediamine (H2salen)-type ligands 3 (cf. Schemes 1 and 3) are efficient ligands for the enantioselective addition of diethylzinc to aldehydes. There is ample evidence that an active bimetallic catalyst forms an effective chiral pocket (see Fig. 2); of a series of first-row transition-metal complexes with these ligands, the most stereoselective were the Co(II) complexes (see Fig. 1). Best ee values as well as the fastest rates (see Tables 2 and 3) were obtained with these Co(II) complexes when an EtO substituent was present at C(3) of the salicylaldehyde residues of ligand 3 (R1 = EtO), i.e., complex [Co(II)(3'h)] produce d up to 93% ee with aromatic aldehydes and 78% ee for aliphatic aldehydes (see Table 4).
