1.Highly enantioselective copper-catalyzed conjugate addition of diethylzinc to enones using chiral spiro phosphoramidites as ligands.
Zhou H1, Wang WH, Fu Y, Xie JH, Shi WJ, Wang LX, Zhou QL. J Org Chem. 2003 Feb 21;68(4):1582-4.
Novel monodentate chiral spiro phosphoramidite ligands have been readily synthesized in good yields from enantiomerically pure 1,1'-spirobiindane-7,7'-diol. The new ligands were highly efficient in the copper-catalyzed conjugate addition of Et(2)Zn to enones with up to 98% enantiomeric excess.
2.Antibacterial Biphenanthrenes from the Fibrous Roots of Bletilla striata.
Qian CD1, Jiang FS1, Yu HS1, Shen Y1, Fu YH1, Cheng DQ1, Gan LS2, Ding ZS1. J Nat Prod. 2015 Apr 24;78(4):939-43. doi: 10.1021/np501012n. Epub 2015 Mar 11.
Four new 9',10'-dihydro-biphenanthrenes, including an unprecedented 1,2'-linked biphenanthrene, 4,7,3',5'-tetramethoxy-9',10'-dihydro(1,2'-biphenanthrene)-2,7'-diol (1), a new 1,3'-linked biphenanthrene, 4,7,7'-trimethoxy-9',10'-dihydro(1,3'-biphenanthrene)-2,2',5'-triol (2), and two new 1,1'-linked biphenanthrenes, 4,7,4'-trimethoxy-9',10'-dihydro(1,1'-biphenanthrene)-2,2',7'-triol (3) and 4,7,3',5'-tetramethoxy-9',10'-dihydro(1,1'-biphenanthrene)-2,2',7'-triol (4), as well as two known biphenanthrenes (5, 6), were isolated from a 95% ethanol extract of the fibrous roots of Bletilla striata. Their structures were determined by spectroscopic and spectrometric methods. Atropisomerism of these compounds was considered based on their chiral optical properties and potential energy surface scans at the ab initio HF/3-21G level, which revealed their racemic mixture form. Compounds 2-6 showed potent antibacterial activities against six Gram-positive bacterial strains.
3.Synthesis and application of chiral spiro phospholane ligand in Pd-catalyzed asymmetric allylation of aldehydes with allylic alcohols.
Zhu SF1, Yang Y, Wang LX, Liu B, Zhou QL. Org Lett. 2005 Jun 9;7(12):2333-5.
[reaction: see text] A novel chiral monodentate spiro phenylphospholane ligand 4 was prepared from a readily accessible, enantiomerically pure 1,1'-spirobiindane-7,7'-diol in high yield. This ligand has proven to be efficient for Pd-catalyzed enantioselective allylation of aldehydes with allylic alcohols. Aromatic, heteroaromatic, and aliphatic aldehydes gave homoallylic alcohols in good enantioselectivities (up to 83% ee) and excellent anti diastereoselectivities (up to 99:1 dr).
4.Rhodium-catalyzed asymmetric hydrogenation of functionalized olefins using monodentate spiro phosphoramidite ligands.
Fu Y1, Guo XX, Zhu SF, Hu AG, Xie JH, Zhou QL. J Org Chem. 2004 Jul 9;69(14):4648-55.
Novel chiral monodentate phosphorus ligands, SIPHOS, were conveniently synthesized from 1,1'-spirobiindane-7,7'-diol. The Rh complexes of SIPHOS can catalyze the hydrogenation of alpha-dehydroamino esters in mild conditions, providing alpha-amino acid derivatives in up to 99% ee. Enamides and beta-dehydroamino esters can also be hydrogenated in good to excellent enantioselectivities (up to 99% and 94% ee, respectively). The SIPHOS ligand with smaller alkyl groups on the N-atom afforded higher enantioselectivity. The X-ray analysis of single crystal showed that the structure of Rh/SIPHOS catalyst is [Rh(COD)((S)-SIPHOS-Me)(2)](+), which clarified the configuration of the catalyst with the monodentate chiral phosphorus ligand in Rh-catalyzed asymmetric hydrogenation. A positive nonlinear effect in the relationship of the optical purities of ligand and product was observed in the hydrogenation of dehydroamino acid derivatives. The kinetic study of hydrogenation showed that the reaction is zero order in the concentration of substrate and first order in the concentration of Rh catalyst and the hydrogenation pressure.
