114182-19-3Relevant academic research and scientific papers
Enantiopure Chiral Concave 1,10-Phenanthrolines
Reck, Lisa M.,Haberhauer, Gebhard,Lüning, Ulrich
, p. 1119 - 1131 (2016)
Chiral information has been introduced into concave 1,10-phenanthrolines of different ring sizes by using a 2,7-disubstituted naphthalene bridgehead, which causes axial chirality. A tetraphenolic 2-(dihydroxynaphthyl)-9-(dihydroxyphenyl)-1,10-phenanthroline was synthesized as a key intermediate. Two strategies were followed to obtain the bimacrocyclic chiral concave 1,10-phenanthrolines: quadruple Williamson ether synthesis or alkenylation of the OH groups and subsequent ring-closing metathesis followed by hydrogenation. The overall yields of bimacrocyles 19 were 10 to 17 % starting from the respective Suzuki coupling of the substituted arenes 11 and 13 to 2,9-dichloro-1,10-phenanthroline (5). Racemic mixtures of the three concave 1,10-phenanthrolines 19 were separated by using chiral high-performance liquid chromatography (HPLC) techniques, and their absolute stereochemistry was assigned by comparison of simulated and experimental circular dichroism (CD) spectra. The enantiopure concave 1,10-phenanthrolines were used as ligands in a copper-catalysed cyclopropanation, and their selectivity was determined by chiral gas chromatography (GC).
Concave 1,10-phenanthrolines as ligands for cyclopropanations - Towards a deeper understanding of the stereoselectivity
Eggers, Friederike,Luening, Ulrich
experimental part, p. 2328 - 2341 (2009/09/05)
Four new mono- and bimacrocyclic 1,10-phenanthrolines - 3b and 4a-c - containing aryl bridgeheads have been synthe- sised. The etherification of the aryl bridgeheads was accomplished by Williamson or Mitsunobu reactions. A key step in the synthesis of the macrocyclic phenanthrolines 3 and 4 is the Suzuki coupling of 2,9-diiodo-1,10-phenan- throline (12) with the appropriately substituted boronic acids 17 and 20. Ring-closing metathesis and hydrogenation completed the synthesis. The resulting macrocyclic 1,10-phenan- throlines 3b and 4a-c were tested as ligands in a copper(I)- catalysed stereoselective cyclopropanation.
Concave reagents 32: Syn- and anti-selective cyclopropanation of alkenes with diazoacetates catalyzed by copper(I) complexes of concave 1,10- phenanthrolines
L?ffler, Frank,Hagen, Martin,Lüning, Ulrich
, p. 1826 - 1828 (2007/10/03)
Two classes of concave 1,10-phenanthroline ligands 1 and 2 have been used in the copper(I) catalyzed cyclopropanation of several acyclic and cyclic alkenes 3 with three diazoacetates 4-6. The bimacrocyclic 2,9-diaryl- 1,10-phenanthrolines 1 favor the anti(trans- or exo-) cyclopropanation with anti/syn-selectivities of up to > 99:1 (8g). In contrast, with the 1,10- phenanthroline bridged calix[6]arenes 2 as ligands a rarely observed syn- selective cyclopropanation was achieved. Methyl diazoacetate (6) showed the best syn-selectivities with anti/syn-ratios of up to 14:86 (9g).
Cyclopropanation of alkenes with ethyl diazoacetate: Copper(I) complexes of concave 1,10-phenanthrolines as diastereoselective catalysts
Hagen, Martin,Liining, Ulrich
, p. 231 - 234 (2007/10/03)
Concave 1,10-phenanthrolines 1a-c have been used as ligands in the copper(I)-catalyzed cyclopropanation of alkenes 2 with ethyl diazoacetate. The complexes proved to be efficient cyclopropanation catalysts and exhibited an enhanced diastereoselectivity, particularly in the reactions of cyclic alkenes 2b-d. The preferred formation of exo-cyclopropanes 3b-d can be explained by the concave shape of these catalysts. VCH Verlagsgcsellschaft mbH.
