Enantioselective oxidative-coupling of polycyclic phenols
摘要:
Enantioselective oxidative-coupling of polycyclic phenols, such as 2-anthracenol, 9- or 3-phenanthrol, and 5-chrysenol was established by using vanadium(V/IV) catalysis under air or 02 as a co-oxidant. In the vanadium catalyzed reaction, the corresponding coupling products were obtained in good to excellent yields with up to 93% enantiomeric excess. (C) 2014 Elsevier Ltd. All rights reserved.
spirosilabi[fluorene] moiety, the two helicene units in 4 are symmetrically and nearly perpendicularly arranged. (P,P)-4 and (M,M)-4 exhibit unique optical properties attributable to the LUMO spiro-conjugation between the two sila[7]helicene units.
A New Optically Active Monodentate Phosphine Ligand, (<i>R</i>)-(+)-3-Diphenylphosphino-3′-methoxy-4,4′-biphenanthryl (MOP-phen): Preparation and Use for Palladium-Catalyzed Asymmetric Reduction of Allylic Esters with Formic Acid
(R)-(+)-3-Diphenylphosphino-3′-methoxy-4,4′-biphenanthryl (MOP-phen, 8) was prepared starting with (-)-3,3′-dihydroxy-4,4′-biphenanthryl. The absolute configuration of (+)-8 was determined to be R by X-ray crystal structure analysis of its Ï-allylpalladium complex. The monodentate optically active phosphine 8 was found to be a more enantioselective ligand than (R)-(+)-2-diphenylphosphino-2′-methoxy-1,1′-binaphthyl (MOP, 1a) for palladium-catalyzed asymmetric reduction of allylic esters with formic acid giving optically active olefins of up to 85% ee.
A one-pot transformation of biaryl dicarboxylic acids to (NH)-phenanthridinone derivatives based on a Curtiusrearrangement and subsequent basic hydrolysis was developed. This method is also applicable for the preparation of optically active amide-functionalized [7]helicene-like molecules. Furthermore, aza[5]helicene derivatives with a phosphate moiety were isolated as a product of the Curtius rearrangement
开发了基于 Curtius 重排和随后的碱性水解的联芳基二羧酸向 ( NH )-菲啶酮衍生物的一锅法转化。该方法也适用于光学活性酰胺官能化[7]类螺烯分子的制备。此外,在带有硫属元素原子的底物的情况下,具有磷酸盐部分的氮杂[5]螺烯衍生物被分离为 Curtius 重排步骤的产物。通过 X 射线衍射分析揭示了这些产品的立体结构,表明硫属元素键合和磷元素键合相互作用可能有助于它们的稳定性。进一步研究了类螺烯分子的构型稳定性及其手性。
Benzylic-type couplings provide an important asymmetric entry to functionalized, non-racemic helicenes
Benzylic-type couplings are key reactions to make non-racemic helicenes.
苯基型偶联反应是制备非消旋螺旋烯的关键反应。
Synthesis and chiral recognition of optically active crown ethers incorporating a 4,4′-biphenanthryl; moiety as the chiral centre
作者:Koji Yamamoto、Koji Noda、Yoshio Okamoto
DOI:10.1039/c39850001065
日期:——
Two chiral crown ethers (+)-(S)-(4) and (–)-(R,R)-(5) with a 4,4′-biphenanthryl moiety as the chiralcentre have been prepared, and their chiralrecognition properties were examined to show that (+)-(S)-(4) has a high enantiomer selectivity for 2-aminotetralin and 1,2-diphenylethylamine.