114784-19-9Relevant academic research and scientific papers
A new class of tunable dendritic diphosphine ligands: Synthesis and applications in the Ru-catalyzed asymmetric hydrogenation of functionalized ketones
Ma, Baode,Miao, Tingting,Sun, Yihua,He, Yanmei,Liu, Ji,Feng, Yu,Chen, Hui,Fan, Qing-Hua
supporting information, p. 9969 - 9978 (2014/08/18)
A series of tunable G0-G3 dendritic 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP) ligands was prepared by attaching polyaryl ether dendrons onto the four phenyl rings on the P atoms. Their ruthenium complexes were employed in the asymmetric hydrogenation of β-ketoesters, α-ketoesters, and α-ketoamides to reveal the effects of dendron size on the catalytic properties. The second- and third-generation catalysts exhibited excellent enantioselectivities, which are remarkably higher than those obtained from the small molecular catalysts and the first-generation catalyst. Molecular modeling indicates that the incorporation of bulky dendritic wedges can influence the steric environments around the metal center. In addition, the ruthenium catalyst bearing a second-generation dendritic ligand could be recycled and reused seven times without any obvious decrease in enantioselectivity.
An improved asymmetric Reformatsky reaction mediated by (-)-N,N-dimethylaminoisoborneol
Kloetzing, Ralf J.,Thaler, Tobias,Knochel, Paul
, p. 1125 - 1128 (2007/10/03)
(-)-N,N-Dimethylaminoisoborneol ((-)-DAIB) was found to be an excellent ligand for the enantioselective addition of Reformatsky reagents to aromatic and aliphatic aldehydes. Enantioselectivities up to 93% ee were obtained with sulfur-containing aldehydes.
Dirhodium(II) tetrakis[N-benzene-fused phthaloyl-(S)-piperidinonate] as a chiral lewis acid: Catalytic enantioselective aldol reactions of acetate-derived silylketene acetals and aldehydes
Washio, Takuya,Nakamura, Seiichi,Anada, Masahiro,Hashimoto, Shunichi
, p. 567 - 578 (2007/10/03)
A first example of chiral dirhodium(II) complex-catalyzed enantioselective Mukaiyama aldol reactions is described. The aldol addition reaction of methyl acetate-derived trimethylsilylketene acetal with specific aldehydes such as benzyloxyacetaldehyde and electron-poor aromatic aldehydes is effectively catalyzed by dirhodium(II) tetrakis[N-benzene-fused phthaloyl-(S)-piperidinonate] (1a), providing silylated aldol adducts in up to 94% ee.
Asymmetric Hydrogenation of 3,5-Dioxoesters Catalyzed by Ru-binap Complex: A Short Step Asymmetric Synthesis of 6-Substituted 5,6-dihydro-2-pyrones
Shao, Liming,Kawano, Hiroyuki,Saburi, Masahiko,Uchida, Yasuzo
, p. 1997 - 2010 (2007/10/02)
Asymmetric hydrogenation of 3,5-dioxoesters 1a-c using Ru2Cl4((R) or (S)-binap)2(NEt3) as the catalyst gave dominantly anti 3,5-dihydroxyesters 2, which were then converted into unsaturated lactones 5a-b (ca. 80percent e.e.).The pathway of the hydrogenation reaction was also investigated by asymmetric hydrogenation of (R)- or (S)-5-hydroxy-3-oxoesters 8a-c.It was revealed that the Ru-binap catalyzed hydrogenation of 1a-b proceed dominantly via the β-diketone mode.A convenient asymmetric synthesis of hydroxylactone 3c and unsaturated lactone 5c was presented.Key words: 3,5-dioxoester; Ru-binap catalyst; asymmetric hydrogenation; asymmetric synthesis; lactone
STUDIES ON THE SYNTHESIS OF THE APLYSIATOXINS: SYNTHESIS OF A SELECTIVELY-PROTECTED FORM OF THE C27-C30 (DIHYDROXYBUTANOATE) MOIETY OF OSCILLATOXIN A
Walkup, Robert D.,Cunningham, Raymond T.
, p. 4019 - 4022 (2007/10/02)
A protected form of (R)-3,4-dihydroxybutanoic acid bearing a benzyl protecting group at the C4 hydroxyl and a dimethylthexylsilyl protecting group at the C3 hydroxyl was synthesized via a selective Ag(I)-mediated monobenzylation of (R)-methyl 3,4-dihydroxybutanoate.An alternative synthetic route from a chiral allylic ether was successful but problematic.The acid could be clenly coupled to a model for the C3-C11 moiety of the aplysiatoxins.
