Stereochemical Exploitation of the Chiral (+)-9-Phenyldeltacyclanyl Substituent in Diphosphanes and Their Ni, Pd and Pt Complexes

Abstract

Keywords: Deltacyclenes / Chiral ligands / Phosphanes / Nickel / Palladium / PlatinumThe (+)-9-phenyldeltacyclanyl moiety as a chiral phosphorus substituent contains eight configurationally fixed asymmetric carbon atoms. It is easily obtained from the reaction of norbornadiene and phenylacetylene via a Co-catalyzed enantioselective homo-Diels−Alder reaction, to give (+)-8-phenyldeltacyclene. In the reaction of (+)-8-phenyldeltacyclene with 1,2-(H 2 P) 2 C 6 H 4 the trisubstitution product P,P,PЈ-tris[(+)-9-phenyldeltacyclan-8-yl)-1,2-bis(phosphanyl)benzene, (+) δ -LH, is obtained, in which a single P−H bond at the stereogenic phosphorus atom is left. (+) δ -LH crystallizes as a pure diastereomer, which isomerizes in solution with respect to the secondary phosphorus atom at −20°C resulting in a 64:36 diastereomer mixture. Substitution of the P−H hydrogen atom in (+) δ -LH by benzyl, 3-bromobenzyl, 6-bromo-nhexyl and 3-(diphenylphosphanyl)phenyl gave the bis(terti-

Optically Active Transition Metal Complexes. 130.1Synthesis, Crystal Structures, and Catalytic Properties of Chiral-at-Metal (η6-Arene)ruthenium(II) and (η6-Arene)osmium(II) Half-Sandwich Complexes. Crystallization of Pure Diastereomers versus Diastereomer Mixtures in a 1:1 Ratio

“…This, actually, is the basis for the resolution of racemates by diastereomer separation via crystallization. There are, however, a few examples known with two diastereomers of the same ligand configuration and opposite metal configuration present in the same single crystal. − In the present study three of the new complexes showed the structural peculiarity of a 1:1 diastereomer crystallization including a ruthenium complex, the corresponding intimately related osmium compound of which did not show 1:1 diastereomer crystallization but crystallization as a pure diastereomer in two different modifications, indicating a delicate balance between the 1:1 diastereomer crystallization and the crystallization as a pure diastereomer. This alternative, of fundamental importance for optical resolutions by diastereomer separation via crystallization, will be analyzed.…”

“…1:1 cocrystallization of two diastereomers in the same lattice has been observed occasionally . Interestingly, the phenomenon is frequently encountered in the crystallization of chiral-at-metal (η 6 -arene)ruthenium complexes of the three-legged piano-stool type from solutions containing both diastereomers.…”

Optically Active Transition Metal Complexes. 130.1Synthesis, Crystal Structures, and Catalytic Properties of Chiral-at-Metal (η6-Arene)ruthenium(II) and (η6-Arene)osmium(II) Half-Sandwich Complexes. Crystallization of Pure Diastereomers versus Diastereomer Mixtures in a 1:1 Ratio

“…This, actually, is the basis for the resolution of racemates by diastereomer separation via crystallization. There are, however, a few examples known with two diastereomers of the same ligand configuration and opposite metal configuration present in the same single crystal. − In the present study three of the new complexes showed the structural peculiarity of a 1:1 diastereomer crystallization including a ruthenium complex, the corresponding intimately related osmium compound of which did not show 1:1 diastereomer crystallization but crystallization as a pure diastereomer in two different modifications, indicating a delicate balance between the 1:1 diastereomer crystallization and the crystallization as a pure diastereomer. This alternative, of fundamental importance for optical resolutions by diastereomer separation via crystallization, will be analyzed.…”

“…1:1 cocrystallization of two diastereomers in the same lattice has been observed occasionally . Interestingly, the phenomenon is frequently encountered in the crystallization of chiral-at-metal (η 6 -arene)ruthenium complexes of the three-legged piano-stool type from solutions containing both diastereomers.…”

Phosphines and Related Tervalent Phosphorus Systems

“…This method continues to find use in phosphine synthesis, although the number of applications noted in the period under review is relatively small. Conventional thermal-or free radical-initiated conditions have been used for the addition reactions of the (R)-(þ)-limonene-based secondary phosphine (101, R¼H) to alkenes to give a series of new bicyclic tertiary phosphines (101, R¼alkyl), 228 the addition of (þ)-8-phenyldeltacyclene to 1,2-bis(phosphino)benzene to give the crowded chiral diphosphine (102) as a mixture of two diastereoisomers, 229 addition of secondary phosphines to Nvinylpyrroles to give a series of 2-(1-pyrrolyl)ethylphosphines, 230 addition of phenylphosphine to iminium salts to give the linear NPN-ligands (103), 231 and for the addition of diphenylphosphine (in excess) with vinyl-functionalised polyhedral oligomeric silsesquioxane dendrimers. 232 Base-catalysed conditions have been employed in the addition of secondary phosphines to functionalised alkenes, leading to polyfunctional tertiary phosphines in high yield, 233 and also for the regio-and stereo-specific addition of primary and secondary phosphines to aryl(cyano)alkynes, giving functionalised secondary and tertiary phosphines of Z-configuration.…”

“…676 Subtle differences have been noted in the ability of the 2,4,6-tri-t-butylphenyl and 2,4-di-t-butyl-6-methylphenyl groups to stabilise the P¼C bond of various diphosphaalkenes of the type (228). 677 Routes to a series of diphosphathienoquinones (229) 678 and the Pmetallophosphaalkene (230) (together with the corresponding arsa-and stibaalkenes) 679 have also been developed. New P¼C bonded cage isomers derived from hexaphospha-pentaprismane, P 6 C 4 t Bu 4 have been obtained by uv-irradiation or protonation of the parent system 680 and the stability of a C 2v -symmetric P¼C bonded tetraphosphabarbaralane system has been assessed by theoretical methods.…”

Optically Active Transition Metal Compounds. 135.1Half-Sandwich Complexes [(η5-C5Me5)M(P-P‘)Hal]X with Chiral Metal (Rh, Ir) and Phosphorus Atoms

“…Recently the coordination chemistry of the ligand P-P‘ and its anion toward Ni(II), Pd(II), and Pt(II) was investigated. Mononuclear, dinuclear, and, surprisingly, trinuclear complexes were formed, , in which the square-planar M(II) arrangements did not contribute to stereogenicity. This is different for half-sandwich complexes of the type [Cp*M(P-P‘)Hal]X (M = Rh, Ir) in which the metal atom is a stereogenic center.…”

Optically Active Transition Metal Complexes. 130.1Synthesis, Crystal Structures, and Catalytic Properties of Chiral-at-Metal (η6-Arene)ruthenium(II) and (η6-Arene)osmium(II) Half-Sandwich Complexes. Crystallization of Pure Diastereomers versus Diastereomer Mixtures in a 1:1 Ratio

“…This, actually, is the basis for the resolution of racemates by diastereomer separation via crystallization. There are, however, a few examples known with two diastereomers of the same ligand configuration and opposite metal configuration present in the same single crystal. − In the present study three of the new complexes showed the structural peculiarity of a 1:1 diastereomer crystallization including a ruthenium complex, the corresponding intimately related osmium compound of which did not show 1:1 diastereomer crystallization but crystallization as a pure diastereomer in two different modifications, indicating a delicate balance between the 1:1 diastereomer crystallization and the crystallization as a pure diastereomer. This alternative, of fundamental importance for optical resolutions by diastereomer separation via crystallization, will be analyzed.…”

“…1:1 cocrystallization of two diastereomers in the same lattice has been observed occasionally . Interestingly, the phenomenon is frequently encountered in the crystallization of chiral-at-metal (η 6 -arene)ruthenium complexes of the three-legged piano-stool type from solutions containing both diastereomers.…”

Phosphines and Related Tervalent Phosphorus Systems

“…This method continues to find use in phosphine synthesis, although the number of applications noted in the period under review is relatively small. Conventional thermal-or free radical-initiated conditions have been used for the addition reactions of the (R)-(þ)-limonene-based secondary phosphine (101, R¼H) to alkenes to give a series of new bicyclic tertiary phosphines (101, R¼alkyl), 228 the addition of (þ)-8-phenyldeltacyclene to 1,2-bis(phosphino)benzene to give the crowded chiral diphosphine (102) as a mixture of two diastereoisomers, 229 addition of secondary phosphines to Nvinylpyrroles to give a series of 2-(1-pyrrolyl)ethylphosphines, 230 addition of phenylphosphine to iminium salts to give the linear NPN-ligands (103), 231 and for the addition of diphenylphosphine (in excess) with vinyl-functionalised polyhedral oligomeric silsesquioxane dendrimers. 232 Base-catalysed conditions have been employed in the addition of secondary phosphines to functionalised alkenes, leading to polyfunctional tertiary phosphines in high yield, 233 and also for the regio-and stereo-specific addition of primary and secondary phosphines to aryl(cyano)alkynes, giving functionalised secondary and tertiary phosphines of Z-configuration.…”

“…676 Subtle differences have been noted in the ability of the 2,4,6-tri-t-butylphenyl and 2,4-di-t-butyl-6-methylphenyl groups to stabilise the P¼C bond of various diphosphaalkenes of the type (228). 677 Routes to a series of diphosphathienoquinones (229) 678 and the Pmetallophosphaalkene (230) (together with the corresponding arsa-and stibaalkenes) 679 have also been developed. New P¼C bonded cage isomers derived from hexaphospha-pentaprismane, P 6 C 4 t Bu 4 have been obtained by uv-irradiation or protonation of the parent system 680 and the stability of a C 2v -symmetric P¼C bonded tetraphosphabarbaralane system has been assessed by theoretical methods.…”

Optically Active Transition Metal Compounds. 135.1Half-Sandwich Complexes [(η5-C5Me5)M(P-P‘)Hal]X with Chiral Metal (Rh, Ir) and Phosphorus Atoms

“…Recently the coordination chemistry of the ligand P-P‘ and its anion toward Ni(II), Pd(II), and Pt(II) was investigated. Mononuclear, dinuclear, and, surprisingly, trinuclear complexes were formed, , in which the square-planar M(II) arrangements did not contribute to stereogenicity. This is different for half-sandwich complexes of the type [Cp*M(P-P‘)Hal]X (M = Rh, Ir) in which the metal atom is a stereogenic center.…”

Optically Active Transition Metal Complexes. 130.1Synthesis, Crystal Structures, and Catalytic Properties of Chiral-at-Metal (η6-Arene)ruthenium(II) and (η6-Arene)osmium(II) Half-Sandwich Complexes. Crystallization of Pure Diastereomers versus Diastereomer Mixtures in a 1:1 Ratio

“…This, actually, is the basis for the resolution of racemates by diastereomer separation via crystallization. There are, however, a few examples known with two diastereomers of the same ligand configuration and opposite metal configuration present in the same single crystal. − In the present study three of the new complexes showed the structural peculiarity of a 1:1 diastereomer crystallization including a ruthenium complex, the corresponding intimately related osmium compound of which did not show 1:1 diastereomer crystallization but crystallization as a pure diastereomer in two different modifications, indicating a delicate balance between the 1:1 diastereomer crystallization and the crystallization as a pure diastereomer. This alternative, of fundamental importance for optical resolutions by diastereomer separation via crystallization, will be analyzed.…”

“…1:1 cocrystallization of two diastereomers in the same lattice has been observed occasionally . Interestingly, the phenomenon is frequently encountered in the crystallization of chiral-at-metal (η 6 -arene)ruthenium complexes of the three-legged piano-stool type from solutions containing both diastereomers.…”

Phosphines and Related Tervalent Phosphorus Systems

“…This method continues to find use in phosphine synthesis, although the number of applications noted in the period under review is relatively small. Conventional thermal-or free radical-initiated conditions have been used for the addition reactions of the (R)-(þ)-limonene-based secondary phosphine (101, R¼H) to alkenes to give a series of new bicyclic tertiary phosphines (101, R¼alkyl), 228 the addition of (þ)-8-phenyldeltacyclene to 1,2-bis(phosphino)benzene to give the crowded chiral diphosphine (102) as a mixture of two diastereoisomers, 229 addition of secondary phosphines to Nvinylpyrroles to give a series of 2-(1-pyrrolyl)ethylphosphines, 230 addition of phenylphosphine to iminium salts to give the linear NPN-ligands (103), 231 and for the addition of diphenylphosphine (in excess) with vinyl-functionalised polyhedral oligomeric silsesquioxane dendrimers. 232 Base-catalysed conditions have been employed in the addition of secondary phosphines to functionalised alkenes, leading to polyfunctional tertiary phosphines in high yield, 233 and also for the regio-and stereo-specific addition of primary and secondary phosphines to aryl(cyano)alkynes, giving functionalised secondary and tertiary phosphines of Z-configuration.…”

“…676 Subtle differences have been noted in the ability of the 2,4,6-tri-t-butylphenyl and 2,4-di-t-butyl-6-methylphenyl groups to stabilise the P¼C bond of various diphosphaalkenes of the type (228). 677 Routes to a series of diphosphathienoquinones (229) 678 and the Pmetallophosphaalkene (230) (together with the corresponding arsa-and stibaalkenes) 679 have also been developed. New P¼C bonded cage isomers derived from hexaphospha-pentaprismane, P 6 C 4 t Bu 4 have been obtained by uv-irradiation or protonation of the parent system 680 and the stability of a C 2v -symmetric P¼C bonded tetraphosphabarbaralane system has been assessed by theoretical methods.…”

Optically Active Transition Metal Compounds. 135.1Half-Sandwich Complexes [(η5-C5Me5)M(P-P‘)Hal]X with Chiral Metal (Rh, Ir) and Phosphorus Atoms

“…Recently the coordination chemistry of the ligand P-P‘ and its anion toward Ni(II), Pd(II), and Pt(II) was investigated. Mononuclear, dinuclear, and, surprisingly, trinuclear complexes were formed, , in which the square-planar M(II) arrangements did not contribute to stereogenicity. This is different for half-sandwich complexes of the type [Cp*M(P-P‘)Hal]X (M = Rh, Ir) in which the metal atom is a stereogenic center.…”