s‑Block-Metal-Mediated Hydroamination of Diphenylbutadiyne with Primary Arylamines Using a Dipotassium Tetrakis(amino)calciate Precatalyst

The hydroamination of diphenylbutadiyne with primary arylamines requires a reactive catalyst. In the presence of heterobimetallic K₂[Ca­{N­(H)­Dipp}₄] (Dipp = 2,6-diisopropylphenyl) the performance of this reaction in THF yields 2-<i>tert</i>-butyl-6,7,10,11-tetraphenyl-9<i>H</i>-cyclohepta­[<i>c</i>]­quinoline (<b>1a</b>) and 2-fluoro-6,7,10,11-tetraphenyl-9<i>H</i>-cyclohepta­[<i>c</i>]­quinoline (<b>1b</b>) within 3 days at room temperature when 4-<i>tert</i>-butyl- and 4-fluoroaniline, respectively, have been used. During this catalysis <i>o</i>-CH activation occurs and quinoline derivatives are formed. Blocking the <i>o</i>-CH positions by methyl groups and use of 2,4,6-trimethylaniline under similar reaction conditions leads to the formation of <i>N</i>-mesityl-7-(<i>E</i>)-((mesitylimino)­(phenyl)­methyl)-2,3,6-triphenylcyclohepta-1,3,6-trienylamine (<b>2</b>) containing a β-diketimine unit with a N–H···N hydrogen bridge. NMR experiments with labeled 4-<i>tert</i>-butylaniline verify the transfer of N-bound hydrogen atoms to the newly formed cycloheptatriene ring. If the s-block-metal-mediated hydroamination of diphenylbutadiyne is performed in refluxing THF for 6 days, <i>N-</i>aryl-2,5-diphenylpyrroles <b>3a</b>–<b>d</b> (<b>3a</b>, R = tBu, R′ = H; <b>3b</b>, R = F, R′ = H; <b>3c</b>, R = R′ = Me; <b>3d</b>, R = R′ = H) are obtained regardless of the substitution pattern of the arylamines

Calcium-Mediated Catalytic Synthesis of 1‑(Diorganylamino)-1,4-diphenyl-4-(diphenylphosphanyl)buta-1,3-dienes

The hydroamination of diphenylbutadiyne with 1 equiv of the secondary amines HNRR′ (R/R′ = Ph/Ph, Ph/Me, and pTol/Me) in the presence of catalytic amounts of the tetrakis­(amino)­calciate K₂[Ca­{N­(H)­Dipp}₄] (Dipp = 2,6-diisopropylphenyl) yields the corresponding 1-(diorganylamino)-1,4-diphenylbut-1-ene-3-ynes as a mixture of <i>E</i>/<i>Z</i> isomers. These tertiary alkenylamines react with diphenylphosphane to form RR′N–C­(Ph)CH–CHC­(Ph)–PPh₂ [R/R′ = Ph/Ph (<b>1</b>), Ph/Me (<b>2</b>), and pTol/Me (<b>3</b>)] in the presence of catalytic amounts of [(THF)₄Ca­(PPh₂)₂] or of the same calciate K₂[Ca­{N­(H)­Dipp}₄]. Whereas the hydroamination is regio- (amino group in 1-position) but not stereoselective (formation of <i>E</i> and <i>Z</i> isomers), this second hydrofunctionalization step is regio- (phosphanyl group in 4-position) and stereoselective (only <i>E</i> isomers are formed), finally leading to mixtures of (<i>E</i>,<i>E</i>)- and (<i>Z</i>,<i>E</i>)-1-(diorganylamino)-1,4-diphenyl-4-(diphenylphosphanyl)­buta-1,3-dienes

2,6-Diisopropylphenylamides of Potassium and Calcium: A Primary Amido Ligand in s‑Block Metal Chemistry with an Unprecedented Catalytic Reactivity

Transamination of KN­(SiMe₃)₂ with 2,6-diisopropylphenylamine (2,6-diisopropylaniline) in toluene at ambient temperature yields [K­{N­(H)­Dipp}·KN­(SiMe₃)₂] (<b>1</b>) regardless of the applied stoichiometry. Recrystallization of <b>1</b> in the presence of tetramethylethylenediamine (TMEDA) and tetrahydrofuran (THF) leads to the formation of [(μ-thf)­K₂{N­(H)­Dipp}₂]_∞ (<b>2</b>), whereas potassium bis­(trimethylsilyl)­amide remains in solution. Addition of pentamethyldiethylenetriamine (PMDETA) gives [(pmdeta)­K­{N­(H)­Dipp}]₂ (<b>3</b>). In contrast to the thf and pmdeta adducts, which lead to dissociation of <b>1</b> into homoleptic species, addition of bidentate dimethoxyethane maintains the mixed complex [(dme)­K­{μ-N­(SiMe₃)₂}­{μ-N­(H)­Dipp}­K]₂ (<b>4</b>). A complete transamination of 2,6-diisopropylaniline with KN­(SiMe₃)₂ in toluene at 100 °C yields [K­{N­(H)­Dipp}] (<b>5</b>), which reacts with CaI₂ to give [(thf)_<i>n</i>Ca­{N­(H)­Dipp}₂] (<b>6</b>), [(pmdeta)­Ca­{N­(H)­Dipp}₂] (<b>7</b>), and [(dme)₂Ca­{N­(H)­Dipp}₂] (<b>8</b>), depending on the solvents and coligands. Excess potassium 2,6-diisopropylphenylamide allows the formation of the calciate [K₂Ca­{N­(H)­Dipp}₄]_∞ (<b>9</b>). Hydroamination of diphenylbutadiyne with 2,6-diisopropylaniline in the presence of catalytic amounts of <b>9</b> gives tetracyclic 2,6-diisopropyl-9,11,14,15-tetraphenyl-8-azatetracyclo­[8.5.0.0^1,7.0^2,13]­pentadeca-3,5,7,9,11,14-hexaene (<b>10</b>). Solid-state structures are reported for <b>2</b>–<b>4</b> and <b>7</b>–<b>10</b>. Compound <b>10</b> slowly rearranges to tetracyclic 5a,9-diisopropyl-2,3,10,11-tetraphenyl-5a,6-dihydro-2a¹,6-ethenocyclohepta­[<i>cd</i>]­isoindole (<b>11</b>), which is slightly favored according to quantum chemical studies

2,6-Diisopropylphenylamides of Potassium and Calcium: A Primary Amido Ligand in s‑Block Metal Chemistry with an Unprecedented Catalytic Reactivity

Transamination of KN­(SiMe₃)₂ with 2,6-diisopropylphenylamine (2,6-diisopropylaniline) in toluene at ambient temperature yields [K­{N­(H)­Dipp}·KN­(SiMe₃)₂] (<b>1</b>) regardless of the applied stoichiometry. Recrystallization of <b>1</b> in the presence of tetramethylethylenediamine (TMEDA) and tetrahydrofuran (THF) leads to the formation of [(μ-thf)­K₂{N­(H)­Dipp}₂]_∞ (<b>2</b>), whereas potassium bis­(trimethylsilyl)­amide remains in solution. Addition of pentamethyldiethylenetriamine (PMDETA) gives [(pmdeta)­K­{N­(H)­Dipp}]₂ (<b>3</b>). In contrast to the thf and pmdeta adducts, which lead to dissociation of <b>1</b> into homoleptic species, addition of bidentate dimethoxyethane maintains the mixed complex [(dme)­K­{μ-N­(SiMe₃)₂}­{μ-N­(H)­Dipp}­K]₂ (<b>4</b>). A complete transamination of 2,6-diisopropylaniline with KN­(SiMe₃)₂ in toluene at 100 °C yields [K­{N­(H)­Dipp}] (<b>5</b>), which reacts with CaI₂ to give [(thf)_<i>n</i>Ca­{N­(H)­Dipp}₂] (<b>6</b>), [(pmdeta)­Ca­{N­(H)­Dipp}₂] (<b>7</b>), and [(dme)₂Ca­{N­(H)­Dipp}₂] (<b>8</b>), depending on the solvents and coligands. Excess potassium 2,6-diisopropylphenylamide allows the formation of the calciate [K₂Ca­{N­(H)­Dipp}₄]_∞ (<b>9</b>). Hydroamination of diphenylbutadiyne with 2,6-diisopropylaniline in the presence of catalytic amounts of <b>9</b> gives tetracyclic 2,6-diisopropyl-9,11,14,15-tetraphenyl-8-azatetracyclo­[8.5.0.0^1,7.0^2,13]­pentadeca-3,5,7,9,11,14-hexaene (<b>10</b>). Solid-state structures are reported for <b>2</b>–<b>4</b> and <b>7</b>–<b>10</b>. Compound <b>10</b> slowly rearranges to tetracyclic 5a,9-diisopropyl-2,3,10,11-tetraphenyl-5a,6-dihydro-2a¹,6-ethenocyclohepta­[<i>cd</i>]­isoindole (<b>11</b>), which is slightly favored according to quantum chemical studies