Iridium Porphyrins in CD₃OD: Reduction of Ir(III), CD₃–OD Bond Cleavage, Ir–D Acid Dissociation and Alkene Reactions

Methanol solutions of iridium­(III) tetra­(<i>p</i>-sulfonatophenyl)­porphyrin [(TSPP)­Ir^III] form an equilibrium distribution of methanol and methoxide complexes ([(TSPP)­Ir^III(CD₃OD)_{(2–<i>n</i>)}(OCD₃)_n]^{(3+<i>n</i>)–}). Reaction of [(TSPP)­Ir^III with dihydrogen (D₂) in methanol produces an iridium hydride [(TSPP)­Ir^III–D­(CD₃OD)]^4– in equilibrium with an iridium­(I) complex ([(TSPP)­Ir^I(CD₃OD)]^5–). The acid dissociation constant of the iridium hydride (Ir–D) in methanol at 298 K is 3.5 × 10^–12. The iridium­(I) complex ([(TSPP)­Ir^I(CD₃OD)]^5–) catalyzes reaction of [(TSPP)­Ir^III–D­(CD₃OD)]^4– with CD₃–OD to produce an iridium methyl complex [(TSPP)­Ir^III–CD₃(CD₃OD)]^4– and D₂O. Reactions of the iridium hydride with ethene and propene produce iridium alkyl complexes, but the Ir–D complex fails to give observable addition with acetaldehyde and carbon monoxide in methanol. Reaction of the iridium hydride with propene forms both the isopropyl and propyl complexes with free energy changes (Δ<i>G</i>° 298 K) of −1.3 and −0.4 kcal mol^–1 respectively. Equilibrium thermodynamics and reactivity studies are used in discussing relative Ir–D, Ir–OCD₃ and Ir–CD₂- bond energetics in methanol

Evaluation of the Rh^(II)–Rh^(II) Bond Dissociation Enthalpy for [(TMTAA)Rh]₂ by ¹H NMR T₂ Measurements: Application in Determining the Rh–C(O)– BDE in [(TMTAA)Rh]₂CO

Toluene solutions of the rhodium­(II) dimer of dibenzotetramethylaza[14]­annulene ([(TMTAA)­Rh]₂; (<b>1</b>)) manifest an increase in the line widths for the singlet methine and methyl ¹H NMR resonances with increasing temperature that result from the rate of dissociation of the diamagnetic Rh^II–Rh^II bonded dimer (<b>1</b>) dissociating into paramagnetic Rh^II monomers (TMTAA) Rh (<b>2</b>). Temperature dependence of the rates of Rh^II–Rh^II dissociation give the activation parameters for bond homolysis Δ<i>H</i>^⧧_app = 24(1) kcal mol^–1 and Δ<i>S</i>^⧧_app = 10 (1) cal K^–1 mol^–1 and an estimate for the Rh^II–Rh^II bond dissociation enthalpy (BDE) of 22 kcal mol^–1. Thermodynamic values for reaction of <b>1</b> with CO to form (TMTAA)­Rh–C­(O)–Rh­(TMTAA) (<b>3</b>) Δ<i>H</i>₁° = −14 (1) kcal mol^–1, Δ<i>S</i>₁°= −30(3) cal K^–1 mol^–1) were used in deriving a (TMTAA)­Rh–C­(O)– BDE of 53 kcal mol^–1

Total Synthesis of Macrocarpines D and E via an Enolate-Driven Copper-Mediated Cross-Coupling Process: Replacement of Catalytic Palladium with Copper Iodide

An enolate driven copper-mediated cross-coupling process enabled cheaper and greener access to the key pentacyclic intermediates required for the enantiospecific total synthesis of a number of C-19 methyl substituted sarpagine/macroline indole alkaloids. Replacement of palladium (60–68%) with copper iodide (82–89%) resulted in much higher yields. The formation of an unusual 7-membered cross-coupling product was completely inhibited by using TEMPO as a radical scavenger. Further functionalization led to the first enantiospecific total synthesis of macrocarpines D and E

Total Synthesis of Macrocarpines D and E via an Enolate-Driven Copper-Mediated Cross-Coupling Process: Replacement of Catalytic Palladium with Copper Iodide

An enolate driven copper-mediated cross-coupling process enabled cheaper and greener access to the key pentacyclic intermediates required for the enantiospecific total synthesis of a number of C-19 methyl substituted sarpagine/macroline indole alkaloids. Replacement of palladium (60–68%) with copper iodide (82–89%) resulted in much higher yields. The formation of an unusual 7-membered cross-coupling product was completely inhibited by using TEMPO as a radical scavenger. Further functionalization led to the first enantiospecific total synthesis of macrocarpines D and E

Total Synthesis of Macrocarpines D and E via an Enolate-Driven Copper-Mediated Cross-Coupling Process: Replacement of Catalytic Palladium with Copper Iodide

An enolate driven copper-mediated cross-coupling process enabled cheaper and greener access to the key pentacyclic intermediates required for the enantiospecific total synthesis of a number of C-19 methyl substituted sarpagine/macroline indole alkaloids. Replacement of palladium (60–68%) with copper iodide (82–89%) resulted in much higher yields. The formation of an unusual 7-membered cross-coupling product was completely inhibited by using TEMPO as a radical scavenger. Further functionalization led to the first enantiospecific total synthesis of macrocarpines D and E

Total Synthesis of Macrocarpines D and E via an Enolate-Driven Copper-Mediated Cross-Coupling Process: Replacement of Catalytic Palladium with Copper Iodide

An enolate driven copper-mediated cross-coupling process enabled cheaper and greener access to the key pentacyclic intermediates required for the enantiospecific total synthesis of a number of C-19 methyl substituted sarpagine/macroline indole alkaloids. Replacement of palladium (60–68%) with copper iodide (82–89%) resulted in much higher yields. The formation of an unusual 7-membered cross-coupling product was completely inhibited by using TEMPO as a radical scavenger. Further functionalization led to the first enantiospecific total synthesis of macrocarpines D and E

Total Synthesis of Macrocarpines D and E via an Enolate-Driven Copper-Mediated Cross-Coupling Process: Replacement of Catalytic Palladium with Copper Iodide

An enolate driven copper-mediated cross-coupling process enabled cheaper and greener access to the key pentacyclic intermediates required for the enantiospecific total synthesis of a number of C-19 methyl substituted sarpagine/macroline indole alkaloids. Replacement of palladium (60–68%) with copper iodide (82–89%) resulted in much higher yields. The formation of an unusual 7-membered cross-coupling product was completely inhibited by using TEMPO as a radical scavenger. Further functionalization led to the first enantiospecific total synthesis of macrocarpines D and E

Efficient Construction of Energetic Materials via Nonmetallic Catalytic Carbon–Carbon Cleavage/Oxime-Release-Coupling Reactions

The exploitation of C–C activation to facilitate chemical reactions is well-known in organic chemistry. Traditional strategies in homogeneous media rely upon catalyst-activated or metal-mediated C–C bonds leading to the design of new processes for applications in organic chemistry. However, activation of a C–C bond, compared with C–H bond activation, is a more challenging process and an underdeveloped area because thermodynamics does not favor insertion into a C–C bond in solution. Carbon–carbon bond cleavage through loss of an oxime moiety has not been reported. In this paper, a new observation of self-coupling via C–C bond cleavage with concomitant loss of oxime in the absence of metals (either metal-complex mediation or catalysis) results in dihydroxylammonium 5,5-bistetrazole-1,10-diolate (TKX-50) as well as <i>N</i>,<i>N</i>′-([3,3′-bi­(1,2,4-oxadiazole)]-5,5′-diyl)­dinitramine, a potential candidate for a new generation of energetic materials

Efficient Construction of Energetic Materials via Nonmetallic Catalytic Carbon–Carbon Cleavage/Oxime-Release-Coupling Reactions

The exploitation of C–C activation to facilitate chemical reactions is well-known in organic chemistry. Traditional strategies in homogeneous media rely upon catalyst-activated or metal-mediated C–C bonds leading to the design of new processes for applications in organic chemistry. However, activation of a C–C bond, compared with C–H bond activation, is a more challenging process and an underdeveloped area because thermodynamics does not favor insertion into a C–C bond in solution. Carbon–carbon bond cleavage through loss of an oxime moiety has not been reported. In this paper, a new observation of self-coupling via C–C bond cleavage with concomitant loss of oxime in the absence of metals (either metal-complex mediation or catalysis) results in dihydroxylammonium 5,5-bistetrazole-1,10-diolate (TKX-50) as well as <i>N</i>,<i>N</i>′-([3,3′-bi­(1,2,4-oxadiazole)]-5,5′-diyl)­dinitramine, a potential candidate for a new generation of energetic materials

Efficient Construction of Energetic Materials via Nonmetallic Catalytic Carbon–Carbon Cleavage/Oxime-Release-Coupling Reactions

The exploitation of C–C activation to facilitate chemical reactions is well-known in organic chemistry. Traditional strategies in homogeneous media rely upon catalyst-activated or metal-mediated C–C bonds leading to the design of new processes for applications in organic chemistry. However, activation of a C–C bond, compared with C–H bond activation, is a more challenging process and an underdeveloped area because thermodynamics does not favor insertion into a C–C bond in solution. Carbon–carbon bond cleavage through loss of an oxime moiety has not been reported. In this paper, a new observation of self-coupling via C–C bond cleavage with concomitant loss of oxime in the absence of metals (either metal-complex mediation or catalysis) results in dihydroxylammonium 5,5-bistetrazole-1,10-diolate (TKX-50) as well as <i>N</i>,<i>N</i>′-([3,3′-bi­(1,2,4-oxadiazole)]-5,5′-diyl)­dinitramine, a potential candidate for a new generation of energetic materials