The Noyori‐Ikariya (arene)Ru(II)/TsDPEN precatalyst has been anchored to amorphous silica and DAV... more The Noyori‐Ikariya (arene)Ru(II)/TsDPEN precatalyst has been anchored to amorphous silica and DAVISIL through the η6‐coordinated arene ligand via a straightforward synthesis and the derived systems, (arene)Ru(II)/TsDPEN@silica and (arene)Ru(II)/TsDPEN@DAVISIL, form highly efficient catalysts for the asymmetric transfer hydrogenation of a range of electron‐rich and electron‐poor aromatic ketones, giving good conversion and excellent ee's under mild reaction conditions. Moreover, catalyst generated in situ immediately prior to addition of substrate and hydrogen donor, by reaction of silica‐supported [(arene)RuCl2]2 with (S,S)‐TsDPEN, was as efficient as that generated from its preformed counterpart [(arene)Ru{(S,S)‐TsDPEN}Cl]@silica. Gratifyingly, the initial TOFs (up to 1085 h−1) and ee's (96–97 %) obtained with these catalysts either rivalled or outperformed those previously reported for catalysts supported by either silica or polymer immobilized through one of the nitrogen ...
Phosphine oxide-decorated polymer immobilized ionic liquid stabilized RuNPs catalyse the hydrogen... more Phosphine oxide-decorated polymer immobilized ionic liquid stabilized RuNPs catalyse the hydrogenation of aryl ketones with remarkable selectivity for the CO bond, complete hydrogenation to the cyclohexylalcohol and hydrogenation of levulinic acid to γ-valerolactone.
The iridium-catalyzed C-H borylation of diethyl phenylphosphonate results in nonselective mono an... more The iridium-catalyzed C-H borylation of diethyl phenylphosphonate results in nonselective mono and bisborylation to afford a near statistical mixture of 3-, 3,5- and 4-boryl substituted aryl phosphonates whereas 3-substituted aryl phosphonates undergo highly regioselective C-H borylation to afford the corresponding meta-phosphonate substituted arylboronic esters as the sole product; the resulting boronic esters were used as nucleophilic reagents in a subsequent palladium-catalyzed Suzuki–Miyaura cross-coupling to generate a range of biarylmonophosphonates. Gratifyingly, the Suzuki–Miyaura cross-coupling can be conducted without purifying the boronic ester which greatly simplifies the synthetic procedure. Graphical Abstract
Platinum nanoparticles stabilized by imidazolium‐based phosphine‐decorated Polymer Immobilized Io... more Platinum nanoparticles stabilized by imidazolium‐based phosphine‐decorated Polymer Immobilized Ionic Liquids (PPh2‐PIIL) catalyze the hydrolytic evolution of hydrogen from sodium borohydride with remarkable efficiency, under mild conditions. The composition of the polymer influences efficiency with the catalyst based on a polyethylene glycol modified imidazolium monomer (PtNP@PPh2‐PEGPIILS) more active than its N‐alkylated counterpart (PtNP@PPh2‐N‐decylPIILS). The maximum initial TOF of 169 moleH2.molcat−1.min−1 obtained at 30 °C with a catalyst loading of 0.08 mol% is among the highest to be reported for the aqueous phase hydrolysis of sodium borohydride catalyzed by a PtNP‐based system. Kinetic studies revealed that the apparent activation energy (Ea) of 23.9 kJ mol−1 for the hydrolysis of NaBH4 catalyzed by PtNP@PPh2‐PEGPIILS is significantly lower than that of 35.6 kJ mol−1 for PtNP@PPh2‐N‐decylPIILS. Primary kinetic isotope effects kH/kD of 1.8 and 2.1 obtained with PtNP@PPh2‐P...
An aqueous phase hydrogenation of α,β-unsaturated aldehydes with remarkable selectivity for the C... more An aqueous phase hydrogenation of α,β-unsaturated aldehydes with remarkable selectivity for the CC double bond under mild conditions.
Phosphino-decorated polymer immobilised ionic liquid-stabilised PdNPs are highly efficient cataly... more Phosphino-decorated polymer immobilised ionic liquid-stabilised PdNPs are highly efficient catalysts for the aqueous phase hydrogenation and transfer hydrogenation of aromatic nitro compounds in batch and continuous flow.
This protocol describes the synthesis of a representative example of the enantiopure biaryl-like ... more This protocol describes the synthesis of a representative example of the enantiopure biaryl-like CATPHOS class of diphosphines, (S)-9,9'-dimethyl-9,9',10,10'-tetrahydro-9,10,9',10'-biethenobianthracene-11,11'-bis(diphenylphosphino)-12,12'-diyl ((S)-Me(2)-CATPHOS), and its derived cationic rhodium-based hydrogenation precatalyst. The C(2)-symmetric framework of Me(2)-CATPHOS is the result of a regioselective Diels-Alder cycloaddition between 1,4-bis(diphenylphosphinoyl)buta-1,3-diyne and 9-methylanthracene, such that the bulky methyl-substituted bridgehead carbon atoms are attached to C2 and C3 of the 1,3-butadiene tether. Enantiopure Me(2)-CATPHOS is obtained in an operationally straightforward three-step procedure and isolated in ∼50-60% overall yield and <99% enantiopurity, after diastereoselective resolution with (2R,3R)-(-)-2,3-O-dibenzoyltartaric acid. The derived rhodium complex forms a highly effective catalyst for the asymmetric hydrogenation of a range of dehydroamino acid derivatives, as well as (E)-β-aryl-(enamido)phosphonates, giving ee values in excess of 99%, the highest to be reported for the latter class of substrate. The total time required for the synthesis of (S)-Me(2)-CATPHOS, including resolution, reduction and crystallizations, is 130 h and preparation of the corresponding rhodium precatalyst requires an additional 24-26 h.
Reaction of the chiral anionic ligand [Mo(CO)5(PPhH)]− with [PtCl2(L-L)] affords the neutral trim... more Reaction of the chiral anionic ligand [Mo(CO)5(PPhH)]− with [PtCl2(L-L)] affords the neutral trimetallic monophosphido bridged complexes [Pt(μ-PPhH)2{Mo-(CO)5}2(L-L)] (L-L = dppe, Ph2PCH2CH2PPh2, 2; dpae, Ph2AsCH2CH2AsPh2, 3; dppe′, cis-Ph2PCH=CHPPh2, 4). Compounds 2–4 are the first examples of heterometallic complexes that contain two chiral primary phosphido bridges existing as pairs of diastereoisomers. [Pt(μ-PPhH)2{Mo(CO)5}2(dppe)] (2) has been characterized spectroscopically and by a single-crystal X-ray analysis. The molecular structure of 2 can be considered either as Mo2Pt phosphido-bridged trimer or a square-planar PtII complex bonded to one chelating dppe and two anionic phosphine ligands. The latter PtP4 description successfully accounts for the line broadening observed in the 31P{1H} NMR spectra of 2–4, which can be understood in terms of the existence of several interconverting rotameric forms arising from restricted rotation about the Pt-phosphido bond. The PtPMo angles of 122.1(1) and 123.5(1)° are some of the largest ever to be reported for phosphido-bridged heterometallics, reflecting the long PtMo separations [4.349(2) and 4.320(2) Å] and the electronic and structural flexibility of the phosphido bridge. The PtMo compound [Pt(μ-PPhH)2{Mo-(CO)4} (dppe)] (5), comprised of one neutral and one dianionic chelate ligand, was prepared from [Li]2[Mo(CO)5(PPhH)2] and [PtCl2(dppe)] and was shown to contain a conformationally rigid PtP4 structure with characteristically sharp 31P resonances. The 31P{1H} NMR spectrum of 5 is rich with information analysing as two overlapping AA′XX′ spin systems together with their AA′XX′M (M = 195Pt) counterparts. The values of 2J(P-P) and are significantly lower for PPhH{Mo(CO)5}− than dppe, a difference that cannot be accounted for solely on the basis of bond length variations. Meso-[Pt(μ-PPhH)2{Mo(CO)5}2(dppe)] (2) is thermodynamically unstable, undergoing a rapid intramolecular elimination of [Mo(CO)6] to generate [Pt(μ-PPhH)2{Mo(CO)4} (dppe)] (5), while its racemic diastereoisomer, that which was observed in the crystal, decomposes to unidentified phosphorus-containing products.
Deprotonation of the primary phosphine complex [Mo(CO)5(PPhH2)] generated [Mo(CO)5(PPhH)]−, a chi... more Deprotonation of the primary phosphine complex [Mo(CO)5(PPhH2)] generated [Mo(CO)5(PPhH)]−, a chiral anionic ligand which reacted readily with cis- or trans-[PtCl2(PEt3)2] via facile nucleophilic substitution of one or both chloride ligands to afford trans-[PtCl(PEt3)2(μ-PPhH)∗Mo(CO)5∗] (1) and cis- and trans-[Pt(PEt3)2(μ-PPhH)2∗Mo(CO)5∗2] (2), respectively. These are rare examples of heterometallic complexes containing primary phosphido bridges. Compound (1) can be described either as the square-planar Pt11 complex with the anionic ligand PPhH∗Mo(CO)5∗− or as the PtMo phosphido-bridged dimer trans-[PtCl(PEt3)2(μ-PPhH)∗Mo(CO)5∗]. As a phosphido-bridged heterobimetallic (1) possesses an exceptionally large PtPMo angle [120.9(1) °] reflecting the long PtMo nonbonding interaction (4.5 Å). Compound 2 can correspondingly be described either as a phosphido-bridged PtMo2 trimer or a square-planar arrangement of two neutral PEt3 and two anionic PPhH∗Mo(CO)5∗ ligands at Pt. The low-temperature 31P∗1H∗ NMR spectrum of 1 showed several ABXY spin systems together with their associated ABXYM () counterparts and variable-temperature studies revealed the dynamic interconversion of several rotametric isomers arising from restricted rotation about the PtPμ bond. The 31P∗1H∗ NMR spectrum of trans-2 shows its two possible RR/SS and meso diastereoisomers, the latter existing in clearly identifiable rotameric forms which interconvert slowly at −75°C. We note very different values between for the anionic ligands [PPhH∗Mo(CO)5∗]− and PEt3, unattributable to bond length variation but which must reflect reduced s-orbital contribution to the PtP bond of the anionic phosphines PPhH∗Mo(CO)5∗.
The Noyori‐Ikariya (arene)Ru(II)/TsDPEN precatalyst has been anchored to amorphous silica and DAV... more The Noyori‐Ikariya (arene)Ru(II)/TsDPEN precatalyst has been anchored to amorphous silica and DAVISIL through the η6‐coordinated arene ligand via a straightforward synthesis and the derived systems, (arene)Ru(II)/TsDPEN@silica and (arene)Ru(II)/TsDPEN@DAVISIL, form highly efficient catalysts for the asymmetric transfer hydrogenation of a range of electron‐rich and electron‐poor aromatic ketones, giving good conversion and excellent ee's under mild reaction conditions. Moreover, catalyst generated in situ immediately prior to addition of substrate and hydrogen donor, by reaction of silica‐supported [(arene)RuCl2]2 with (S,S)‐TsDPEN, was as efficient as that generated from its preformed counterpart [(arene)Ru{(S,S)‐TsDPEN}Cl]@silica. Gratifyingly, the initial TOFs (up to 1085 h−1) and ee's (96–97 %) obtained with these catalysts either rivalled or outperformed those previously reported for catalysts supported by either silica or polymer immobilized through one of the nitrogen ...
Phosphine oxide-decorated polymer immobilized ionic liquid stabilized RuNPs catalyse the hydrogen... more Phosphine oxide-decorated polymer immobilized ionic liquid stabilized RuNPs catalyse the hydrogenation of aryl ketones with remarkable selectivity for the CO bond, complete hydrogenation to the cyclohexylalcohol and hydrogenation of levulinic acid to γ-valerolactone.
The iridium-catalyzed C-H borylation of diethyl phenylphosphonate results in nonselective mono an... more The iridium-catalyzed C-H borylation of diethyl phenylphosphonate results in nonselective mono and bisborylation to afford a near statistical mixture of 3-, 3,5- and 4-boryl substituted aryl phosphonates whereas 3-substituted aryl phosphonates undergo highly regioselective C-H borylation to afford the corresponding meta-phosphonate substituted arylboronic esters as the sole product; the resulting boronic esters were used as nucleophilic reagents in a subsequent palladium-catalyzed Suzuki–Miyaura cross-coupling to generate a range of biarylmonophosphonates. Gratifyingly, the Suzuki–Miyaura cross-coupling can be conducted without purifying the boronic ester which greatly simplifies the synthetic procedure. Graphical Abstract
Platinum nanoparticles stabilized by imidazolium‐based phosphine‐decorated Polymer Immobilized Io... more Platinum nanoparticles stabilized by imidazolium‐based phosphine‐decorated Polymer Immobilized Ionic Liquids (PPh2‐PIIL) catalyze the hydrolytic evolution of hydrogen from sodium borohydride with remarkable efficiency, under mild conditions. The composition of the polymer influences efficiency with the catalyst based on a polyethylene glycol modified imidazolium monomer (PtNP@PPh2‐PEGPIILS) more active than its N‐alkylated counterpart (PtNP@PPh2‐N‐decylPIILS). The maximum initial TOF of 169 moleH2.molcat−1.min−1 obtained at 30 °C with a catalyst loading of 0.08 mol% is among the highest to be reported for the aqueous phase hydrolysis of sodium borohydride catalyzed by a PtNP‐based system. Kinetic studies revealed that the apparent activation energy (Ea) of 23.9 kJ mol−1 for the hydrolysis of NaBH4 catalyzed by PtNP@PPh2‐PEGPIILS is significantly lower than that of 35.6 kJ mol−1 for PtNP@PPh2‐N‐decylPIILS. Primary kinetic isotope effects kH/kD of 1.8 and 2.1 obtained with PtNP@PPh2‐P...
An aqueous phase hydrogenation of α,β-unsaturated aldehydes with remarkable selectivity for the C... more An aqueous phase hydrogenation of α,β-unsaturated aldehydes with remarkable selectivity for the CC double bond under mild conditions.
Phosphino-decorated polymer immobilised ionic liquid-stabilised PdNPs are highly efficient cataly... more Phosphino-decorated polymer immobilised ionic liquid-stabilised PdNPs are highly efficient catalysts for the aqueous phase hydrogenation and transfer hydrogenation of aromatic nitro compounds in batch and continuous flow.
This protocol describes the synthesis of a representative example of the enantiopure biaryl-like ... more This protocol describes the synthesis of a representative example of the enantiopure biaryl-like CATPHOS class of diphosphines, (S)-9,9'-dimethyl-9,9',10,10'-tetrahydro-9,10,9',10'-biethenobianthracene-11,11'-bis(diphenylphosphino)-12,12'-diyl ((S)-Me(2)-CATPHOS), and its derived cationic rhodium-based hydrogenation precatalyst. The C(2)-symmetric framework of Me(2)-CATPHOS is the result of a regioselective Diels-Alder cycloaddition between 1,4-bis(diphenylphosphinoyl)buta-1,3-diyne and 9-methylanthracene, such that the bulky methyl-substituted bridgehead carbon atoms are attached to C2 and C3 of the 1,3-butadiene tether. Enantiopure Me(2)-CATPHOS is obtained in an operationally straightforward three-step procedure and isolated in ∼50-60% overall yield and <99% enantiopurity, after diastereoselective resolution with (2R,3R)-(-)-2,3-O-dibenzoyltartaric acid. The derived rhodium complex forms a highly effective catalyst for the asymmetric hydrogenation of a range of dehydroamino acid derivatives, as well as (E)-β-aryl-(enamido)phosphonates, giving ee values in excess of 99%, the highest to be reported for the latter class of substrate. The total time required for the synthesis of (S)-Me(2)-CATPHOS, including resolution, reduction and crystallizations, is 130 h and preparation of the corresponding rhodium precatalyst requires an additional 24-26 h.
Reaction of the chiral anionic ligand [Mo(CO)5(PPhH)]− with [PtCl2(L-L)] affords the neutral trim... more Reaction of the chiral anionic ligand [Mo(CO)5(PPhH)]− with [PtCl2(L-L)] affords the neutral trimetallic monophosphido bridged complexes [Pt(μ-PPhH)2{Mo-(CO)5}2(L-L)] (L-L = dppe, Ph2PCH2CH2PPh2, 2; dpae, Ph2AsCH2CH2AsPh2, 3; dppe′, cis-Ph2PCH=CHPPh2, 4). Compounds 2–4 are the first examples of heterometallic complexes that contain two chiral primary phosphido bridges existing as pairs of diastereoisomers. [Pt(μ-PPhH)2{Mo(CO)5}2(dppe)] (2) has been characterized spectroscopically and by a single-crystal X-ray analysis. The molecular structure of 2 can be considered either as Mo2Pt phosphido-bridged trimer or a square-planar PtII complex bonded to one chelating dppe and two anionic phosphine ligands. The latter PtP4 description successfully accounts for the line broadening observed in the 31P{1H} NMR spectra of 2–4, which can be understood in terms of the existence of several interconverting rotameric forms arising from restricted rotation about the Pt-phosphido bond. The PtPMo angles of 122.1(1) and 123.5(1)° are some of the largest ever to be reported for phosphido-bridged heterometallics, reflecting the long PtMo separations [4.349(2) and 4.320(2) Å] and the electronic and structural flexibility of the phosphido bridge. The PtMo compound [Pt(μ-PPhH)2{Mo-(CO)4} (dppe)] (5), comprised of one neutral and one dianionic chelate ligand, was prepared from [Li]2[Mo(CO)5(PPhH)2] and [PtCl2(dppe)] and was shown to contain a conformationally rigid PtP4 structure with characteristically sharp 31P resonances. The 31P{1H} NMR spectrum of 5 is rich with information analysing as two overlapping AA′XX′ spin systems together with their AA′XX′M (M = 195Pt) counterparts. The values of 2J(P-P) and are significantly lower for PPhH{Mo(CO)5}− than dppe, a difference that cannot be accounted for solely on the basis of bond length variations. Meso-[Pt(μ-PPhH)2{Mo(CO)5}2(dppe)] (2) is thermodynamically unstable, undergoing a rapid intramolecular elimination of [Mo(CO)6] to generate [Pt(μ-PPhH)2{Mo(CO)4} (dppe)] (5), while its racemic diastereoisomer, that which was observed in the crystal, decomposes to unidentified phosphorus-containing products.
Deprotonation of the primary phosphine complex [Mo(CO)5(PPhH2)] generated [Mo(CO)5(PPhH)]−, a chi... more Deprotonation of the primary phosphine complex [Mo(CO)5(PPhH2)] generated [Mo(CO)5(PPhH)]−, a chiral anionic ligand which reacted readily with cis- or trans-[PtCl2(PEt3)2] via facile nucleophilic substitution of one or both chloride ligands to afford trans-[PtCl(PEt3)2(μ-PPhH)∗Mo(CO)5∗] (1) and cis- and trans-[Pt(PEt3)2(μ-PPhH)2∗Mo(CO)5∗2] (2), respectively. These are rare examples of heterometallic complexes containing primary phosphido bridges. Compound (1) can be described either as the square-planar Pt11 complex with the anionic ligand PPhH∗Mo(CO)5∗− or as the PtMo phosphido-bridged dimer trans-[PtCl(PEt3)2(μ-PPhH)∗Mo(CO)5∗]. As a phosphido-bridged heterobimetallic (1) possesses an exceptionally large PtPMo angle [120.9(1) °] reflecting the long PtMo nonbonding interaction (4.5 Å). Compound 2 can correspondingly be described either as a phosphido-bridged PtMo2 trimer or a square-planar arrangement of two neutral PEt3 and two anionic PPhH∗Mo(CO)5∗ ligands at Pt. The low-temperature 31P∗1H∗ NMR spectrum of 1 showed several ABXY spin systems together with their associated ABXYM () counterparts and variable-temperature studies revealed the dynamic interconversion of several rotametric isomers arising from restricted rotation about the PtPμ bond. The 31P∗1H∗ NMR spectrum of trans-2 shows its two possible RR/SS and meso diastereoisomers, the latter existing in clearly identifiable rotameric forms which interconvert slowly at −75°C. We note very different values between for the anionic ligands [PPhH∗Mo(CO)5∗]− and PEt3, unattributable to bond length variation but which must reflect reduced s-orbital contribution to the PtP bond of the anionic phosphines PPhH∗Mo(CO)5∗.
Uploads
Papers by Simon Doherty