Weichih Lee | University of Nevada, Reno (original) (raw)
Papers by Weichih Lee
Inorganica Chimica Acta, 2015
Two chiral chelating 1,3,5-triaza-7phosphaadamantane (PTA) derivatives were synthesized, in racem... more Two chiral chelating 1,3,5-triaza-7phosphaadamantane (PTA) derivatives were synthesized, in racemic form, by addition of ClP i Pr 2 or ClP(N i Pr) 2 (CH 2) 2 to lithiated PTA. PTA-P i Pr 2 (1) and PTA-P(N i Pr) 2 (CH 2) 2 (2) were isolated in good yield, 73 % and 56 % respectively, and fully characterized by multinuclear NMR spectroscopy, mass spectrometry, and X-ray crystallography. PTA-P i Pr 2 is highly air sensitive, but stable and somewhat soluble in degassed water. PTA-P(N i Pr) 2 (CH 2) 2 (2) is air-stable, but decomposes in water over the course of hours. Two tungsten tetracarbonyl complexes were prepared by addition of the PTA-PR 2 to [W(CO) 4 (pip) 2 ] and characterized by NMR and IR spectroscopies and X-ray crystallography in the case of [W(CO) 4 (PTA-P i Pr 2)]. Based on IR spectroscopy PTA-P i Pr 2 (1) is more electron donating than PTA-P(N i Pr) 2 (CH 2) 2 (2) or the previously published PTA-PPh 2. Products isolated from the reaction of [(η 6toluene)RuCl 2 ] 2 with two equivalents of 1 were found to contain monodentate (κ 1), bidentate (κ 2), and possibly bridging coordination modes of PTA-P i Pr 2. These ruthenium complexes were explored as catalysts for aqueous phase nitrile hydration. Of the ruthenium explored [(η 6-toluene)RuCl 2 (κ 1-PTA-P i Pr 2)] (7) was the most active towards nitrile hydration. In the presence of air at 100 °C 7 converted various nitriles to the respective amides with 43-99% conversions in 7 h.
Organic letters, Jan 19, 2014
The catalytic method features a cooperative interaction between Ni and Al imparting remote C-H al... more The catalytic method features a cooperative interaction between Ni and Al imparting remote C-H alkenylation at the C5 position of imidazo[1,5-a]pyridine with alkynes at mild conditions. Exclusion of AlMe3 switches the selectivity to the C3 position. Reactions with styrene and other olefinic substrates affording C5-adducts by Ni/Al catalysis are also included.
Polyhedron, 2010
Eight group 12 metal complexes of PTA derivatives,[ZnCl2 (OPTA)(H2O)](1),[ZnCl2 (μ-OPTA)] n (2),[... more Eight group 12 metal complexes of PTA derivatives,[ZnCl2 (OPTA)(H2O)](1),[ZnCl2 (μ-OPTA)] n (2),[CdCl2 (OPTA)(H2O)](3),[Cd (OPTA)(H2O) Br2](4),[CdI2 (κ1-OPTA)(μ-OPTA)](5),[HgCl2 (μ-OPTA)] n (6),[ZnCl2 (SPTAH)(SPTAZnCl3)](7), and [CdCl2 (SPTA)( ...
Journal of Organometallic Chemistry, 2014
ABSTRACT The synthesis and characterization of silver, copper and gold complexes supported by sev... more ABSTRACT The synthesis and characterization of silver, copper and gold complexes supported by several amino-NHC ligands with different amino side arms was reported. The catalytic activities of copper complexes are examined for arylation of caffeine via C–H bond activation.
Inorganic Chemistry, 2013
A series of β-aminophosphines derived from 1,3,5-triaza-7-phosphaadamantane (PTA) are described. ... more A series of β-aminophosphines derived from 1,3,5-triaza-7-phosphaadamantane (PTA) are described. PTA-CHPhNHPh (1), PTA-CH(p-C(6)H(4)OCH(3))NHPh (2), and PTA-CPh(2)NHPh (3) were prepared in good yield (62-77%) by reaction of lithiated PTA with the corresponding imine followed by hydrolysis. Compounds 1 and 2 were synthesized as pairs of diastereomers which were separated by successive recrystallization from THF/hexane. Compounds 1-3 are somewhat soluble in water (S(25)(o) = 4.8 (1), 4.9 (2), 2.7 (3) g/L). Upon coordination to Ru(II) arene centers both monodentate (κ(1)-P) [RuCl(2)(η(6)-toluene)(1-3)] and bidentate (κ(2)-P,N) [RuCl(η(6)-toluene)(1-3)]Cl coordination modes were observed. Ru(II) arene complexes 4-6 exhibited hemilabile behavior transitioning between κ(1)-P and κ(2)-P,N coordination upon change in solvent or addition of a coordinating ligand such as Cl(-) or CH(3)CN. Complexes (4-6) were found to be active air stable catalysts for the aqueous phase hydration of various nitriles with TOF up to 285 h(-1) and TON of up to 97,000 observed.
Green Chemistry, 2012
ABSTRACT [RuCl2(PTA)4] (PTA = 1,3,5-triaza-7-phosphaadamantane) was found to be a highly active c... more ABSTRACT [RuCl2(PTA)4] (PTA = 1,3,5-triaza-7-phosphaadamantane) was found to be a highly active catalyst for aqueous phase nitrile hydration at 100 °C in air. Near quantitative conversion of aromatic, alkyl, and vinyl nitriles to their corresponding amides was observed. The reaction tolerated ether, hydroxyl, nitro, bromo, formyl, pyridyl, benzyl, alkyl, and olefinic functional groups. Some amides were isolated by simple decantation from the aqueous phase catalyst. Catalyst loading down to 0.001 mol% was examined with turnover numbers as high as 22000 observed. The catalyst was stable for weeks in solution and could be reused more than five times without significant loss of activity.
Chemical Communications, 2014
An efficient Pd-catalyzed cross-dehydrogenative coupling of heteroarenes with alkenes has been de... more An efficient Pd-catalyzed cross-dehydrogenative coupling of heteroarenes with alkenes has been developed. This alkenylation paradigm encompasses a wide range of substrates and provides a straightforward approach toward C2-E-alkenylated azole motifs.
Inorganic Chemistry, 2008
Inorganica Chimica Acta, 2015
Two chiral chelating 1,3,5-triaza-7phosphaadamantane (PTA) derivatives were synthesized, in racem... more Two chiral chelating 1,3,5-triaza-7phosphaadamantane (PTA) derivatives were synthesized, in racemic form, by addition of ClP i Pr 2 or ClP(N i Pr) 2 (CH 2) 2 to lithiated PTA. PTA-P i Pr 2 (1) and PTA-P(N i Pr) 2 (CH 2) 2 (2) were isolated in good yield, 73 % and 56 % respectively, and fully characterized by multinuclear NMR spectroscopy, mass spectrometry, and X-ray crystallography. PTA-P i Pr 2 is highly air sensitive, but stable and somewhat soluble in degassed water. PTA-P(N i Pr) 2 (CH 2) 2 (2) is air-stable, but decomposes in water over the course of hours. Two tungsten tetracarbonyl complexes were prepared by addition of the PTA-PR 2 to [W(CO) 4 (pip) 2 ] and characterized by NMR and IR spectroscopies and X-ray crystallography in the case of [W(CO) 4 (PTA-P i Pr 2)]. Based on IR spectroscopy PTA-P i Pr 2 (1) is more electron donating than PTA-P(N i Pr) 2 (CH 2) 2 (2) or the previously published PTA-PPh 2. Products isolated from the reaction of [(η 6toluene)RuCl 2 ] 2 with two equivalents of 1 were found to contain monodentate (κ 1), bidentate (κ 2), and possibly bridging coordination modes of PTA-P i Pr 2. These ruthenium complexes were explored as catalysts for aqueous phase nitrile hydration. Of the ruthenium explored [(η 6-toluene)RuCl 2 (κ 1-PTA-P i Pr 2)] (7) was the most active towards nitrile hydration. In the presence of air at 100 °C 7 converted various nitriles to the respective amides with 43-99% conversions in 7 h.
Organic letters, Jan 19, 2014
The catalytic method features a cooperative interaction between Ni and Al imparting remote C-H al... more The catalytic method features a cooperative interaction between Ni and Al imparting remote C-H alkenylation at the C5 position of imidazo[1,5-a]pyridine with alkynes at mild conditions. Exclusion of AlMe3 switches the selectivity to the C3 position. Reactions with styrene and other olefinic substrates affording C5-adducts by Ni/Al catalysis are also included.
Polyhedron, 2010
Eight group 12 metal complexes of PTA derivatives,[ZnCl2 (OPTA)(H2O)](1),[ZnCl2 (μ-OPTA)] n (2),[... more Eight group 12 metal complexes of PTA derivatives,[ZnCl2 (OPTA)(H2O)](1),[ZnCl2 (μ-OPTA)] n (2),[CdCl2 (OPTA)(H2O)](3),[Cd (OPTA)(H2O) Br2](4),[CdI2 (κ1-OPTA)(μ-OPTA)](5),[HgCl2 (μ-OPTA)] n (6),[ZnCl2 (SPTAH)(SPTAZnCl3)](7), and [CdCl2 (SPTA)( ...
Journal of Organometallic Chemistry, 2014
ABSTRACT The synthesis and characterization of silver, copper and gold complexes supported by sev... more ABSTRACT The synthesis and characterization of silver, copper and gold complexes supported by several amino-NHC ligands with different amino side arms was reported. The catalytic activities of copper complexes are examined for arylation of caffeine via C–H bond activation.
Inorganic Chemistry, 2013
A series of β-aminophosphines derived from 1,3,5-triaza-7-phosphaadamantane (PTA) are described. ... more A series of β-aminophosphines derived from 1,3,5-triaza-7-phosphaadamantane (PTA) are described. PTA-CHPhNHPh (1), PTA-CH(p-C(6)H(4)OCH(3))NHPh (2), and PTA-CPh(2)NHPh (3) were prepared in good yield (62-77%) by reaction of lithiated PTA with the corresponding imine followed by hydrolysis. Compounds 1 and 2 were synthesized as pairs of diastereomers which were separated by successive recrystallization from THF/hexane. Compounds 1-3 are somewhat soluble in water (S(25)(o) = 4.8 (1), 4.9 (2), 2.7 (3) g/L). Upon coordination to Ru(II) arene centers both monodentate (κ(1)-P) [RuCl(2)(η(6)-toluene)(1-3)] and bidentate (κ(2)-P,N) [RuCl(η(6)-toluene)(1-3)]Cl coordination modes were observed. Ru(II) arene complexes 4-6 exhibited hemilabile behavior transitioning between κ(1)-P and κ(2)-P,N coordination upon change in solvent or addition of a coordinating ligand such as Cl(-) or CH(3)CN. Complexes (4-6) were found to be active air stable catalysts for the aqueous phase hydration of various nitriles with TOF up to 285 h(-1) and TON of up to 97,000 observed.
Green Chemistry, 2012
ABSTRACT [RuCl2(PTA)4] (PTA = 1,3,5-triaza-7-phosphaadamantane) was found to be a highly active c... more ABSTRACT [RuCl2(PTA)4] (PTA = 1,3,5-triaza-7-phosphaadamantane) was found to be a highly active catalyst for aqueous phase nitrile hydration at 100 °C in air. Near quantitative conversion of aromatic, alkyl, and vinyl nitriles to their corresponding amides was observed. The reaction tolerated ether, hydroxyl, nitro, bromo, formyl, pyridyl, benzyl, alkyl, and olefinic functional groups. Some amides were isolated by simple decantation from the aqueous phase catalyst. Catalyst loading down to 0.001 mol% was examined with turnover numbers as high as 22000 observed. The catalyst was stable for weeks in solution and could be reused more than five times without significant loss of activity.
Chemical Communications, 2014
An efficient Pd-catalyzed cross-dehydrogenative coupling of heteroarenes with alkenes has been de... more An efficient Pd-catalyzed cross-dehydrogenative coupling of heteroarenes with alkenes has been developed. This alkenylation paradigm encompasses a wide range of substrates and provides a straightforward approach toward C2-E-alkenylated azole motifs.
Inorganic Chemistry, 2008