1,3-Diphosphapropenes for novel chemistry of metal complexes

2-Methyl-3,3-diphenyl-1-(2,4,6-tri-t-butylphenyl)-1,3-diphosphapropene was obtained as a chelate ligand for palladium(II) and platinum(II) complexes. Sulfurization of 2-methyl-1,3-diphosphapropene mainly gave 3-thioxo-1,3-diphosphapropene which bears a PC-PS skeleton and was used as a ligand of transition-metal complexes. A doubly-sulfurized product of the 1,3-diphosphapropene, 1,3-dithioxo-1,3-diphosphapropene, was isolated and characterized. The palladium(II) complexes containing the ligated 1,3-diphosphapropenes were used for catalytic reactions such as cross-couplings and direct conversion of allyl alcohol to allylaniline.     

Preparation, structure and coordination properties of 3,3-bis(diisopropylamino)-3-thioxo-1-(2,4,6-tri-tert-butylphenyl)-1,3- diphosphapropene

(Z)-1-Chloro-2-(2,4,6-tri-tert-butylphenyl)-2-phosphaethenyllithium was allowed to react with bis(diisopropylamino)-phosphenium triflate to afford the corresponding 1,3-diphosphapropene which was converted to 3-thioxo-1,3-diphosphapropene [(Z)-Mes*P = C(Cl)-P(= S)(NiPr2)2]. The coordination properties of 3-thioxo-1,3'-diphosphapropene were investigated with carbonyltungsten(0) and dichloroplatinum(II) reagents, and the molecular structure of the chelate dichloroplatinum(II) complex was unambiguously determined by X-ray crystallography together with the free ligand. The dichloroplatinum(II) complex underwent intramolecular cyclisation involving C-H activation to give a 5,7-di-tert-butyl-3,3-dimethyl-l-(phosphinomethyl)-1-phosphaindane derivative as well.     

Preparation and coordination properties including catalytic activities of a bulky 2-methyl-3-thioxo-1,3-diphosphapropene

[reaction: see text] 2-Methyl-3,3-diphenyl-3-thioxo-1-(2,4,6-tri-tert-butylphenyl)-1,3-diphosphapropene, which bears a P=C-P=S skeleton, was prepared and used as a ligand of transition-metal complexes. The palladium complexes containing the ligated 3-thioxo-1,3-diphophapropene were stable and used for catalytic reactions such as cross-couplings and direct conversion of allyl alcohol to allylaniline.     

Coordination Chemistry of a Bulky 1,3-Diphosphapropene with Carbonyltungsten(0) Moieties

( Z )-2-Chloro-3,3-diphenyl-1-(2,4,6-tri- t -butylphenyl)-1,3-diphosphapropene was derived from chlorodiphenylphosphine and 1-chloro-2-(2,4,6-tri- t -butylphenyl)-2-phosphaethenyllithium and utilized for complex formations as a ligand of the corresponding carbonyl-tungsten(0) complexes.     

The first structurally authenticated alkali metal 1,3-diphosphaallyl complex [[Bu(t)C(PMes)2]Li(thf)3] (Mes = 2,4,6-Me3C6H2): an alternative synthetic approach to substituted 1,3-diphosphaallyl complexes

Reaction of the phosphavinyl Grignard reagent [Z-MesP=C(Bu(t))MgBr.OEt2]2 (Mes = 2,4,6-Me3C6H2) with MesPCl2 affords the corresponding 1,3-diphosphapropene compound [Z-MesP=C(Bu(t))P(X)Mes] (X = Cl, Br); subsequent reaction with two equivalents of elemental lithium in thf affords the title compound [[Bu(t)C(PMes)2]Li(thf)3], which contains an asymmetric eta1-1,3-diphosphaallyl ligand.     

Preparation,structure, and some coordination properties of 2-chloro-3,3-diphenyl-3-thioxo-1-(2,4,6-tri-t-butylphenyl)-1,3-diphosphapropene

A sterically encumbered 3-thioxo-1,3-diphosphapropene, bearing a P=C-P=S skeleton, was prepared, characterised, and allowed to react with a carbonyltungsten(0) reagent and iodine affording the corresponding chelate tungsten(0) complex and charge-transfer complex with iodine, respectively, which were analysed by the X-ray crystallography.     

Preparation and reactions of 1,3-diphosphacyclobutane-2,4-diyls that feature an amino substituent and/or a carbonyl group

The preparation and properties of a 1-amino-1,3-diphosphacyclobutane-2,4-diyl and a 1-benzoyl-1,3-diphosphacyclobutane-2,4-diyl, which can be regarded as functionalized cyclic biradical derivatives, were investigated. Hydrolysis of 1-diisopropylamino-3-methyl-2,4-bis(2,4,6-tri-tert-butylphenyl)-1,3-diphosphacyclobutane-2,4-diyl (7), which is formed by reaction of Mes*C[triple chemical bond]P (4; Mes*=2,4,6-tBu(3)C(6)H(2)) with lithium diisopropylamide and iodomethane, resulted in ring-opening of the 1,3-diphosphacyclobutane-2,4-diyl skeleton, as well as de-aromatization of one of the Mes* rings. 3-Oxo-1,3-diphosphapropene 8 and 7-phosphabicyclo[4.2.0]octa-1(8),2,4-triene 9 were the resultant products, and these were subsequently characterized. Isomerization and oxidation of 7 occurred in the presence of TEMPO (2,2,6,6-tetramethyl-1-piperidinoxy) to give the first example of a cyclic dimethylenephosphorane derivative, namely 3-oxo-1,3-diphospha-1,4-diene 10. 1-Benzoyl-3-tert-butyl-2,4-bis(2,4,6-tri-tert-butylphenyl)-1,3-diphosphacyclobutane-2,4-diyl (12) was isolated and characterized from the reaction of 4 with tert-butyllithium and benzoyl chloride. Compound 12 was subsequently heated and underwent rearrangement of the benzoyl group and ring-expansion to afford 1-oxo-1H-[1,3]diphosphole 13. Reaction of 4 with lithium diisopropylamide and benzoyl chloride afforded the 2H-[1,2,4]oxadiphosphinine 15, which was probably formed through the 1,3-diphosphacyclobutane-2,4-diyl intermediate 14. Thermolysis of 15 afforded 1-oxo-1H-[1,3]diphosphole 16 in an Arbuzov-type rearrangement.     

New tetrathiafulvalenes containing a 2,5-bis(thiophen-2-yl)pyrrole fragment: Synthesis, optical properties, and electrochemical behavior

The reaction of 1-(3-bromopropyl)-2,5-bis(thiophen-2-yl)-1H-pyrrole with cesium 5-methylsulfanyl-2-thioxo-1,3-dithiole-4-thiolate generated in situ gave previously unknown 4-{3-[2,5-bis(thiophen-2-yl)-1H-pyrrol-1-yl]propylsulfanyl}-5-methylsulfanyl-1,3-dithiole-2-thione, and cross-coupling of the latter with 4,5-disubstituted 1,3-dithiole-2-thiones in the presence of triethyl phosphite afforded new substituted tetrathiafulvalenes containing a 2,5-bis(thiophen-2-yl)pyrrole fragment. Optical properties and electrochemical behavior of the synthesized compounds were studied, and their ability to undergo electropolymerization was confirmed.     

Synthesis of new sulfanyl-, sulfinyl-, and sulfonyl-substituted polychlorobuta-1,3-dienes

New R-sulfanyl-substituted polychlorobuta-1,3-dienes were synthesized by reactions of hexachloro-1,3-butadiene or 1,1,2,4,4-pentachlorobuta-1,3-diene with dimethylbenzenethiols, heptane-1-thiol, and 4-methyl-7-sulfanyl-2H-chromen-2-one. Some sulfides were oxidized to the corresponding sulfoxides and sulfones or brominated with bromine. Among the synthesized compounds, the coumarin derivative, 4-methyl-7-(1,2,3,4,4-pentachlorobuta-1,3-dien-1-ylsulfanyl)-2H-chromen-2-one showed fluorescence properties. 1,1′,1″-[3,4-Dichlorobuta-1,3-diene-1,1,4-triyltris(sulfanediyl)]tris(2,4-dimethylbenzene) reacted with potassium tert-butoxide in petroleum ether to afford a mixture of isomeric 1,1′,1″-[4-chlorobuta-1,2,3-triene-1,1.4-triyltris(sulfanediyl)]tris(2,4-dimethylbenzene) and 1,1′,1″-[2-chlorobut-1-en-3-yne-1,1,4-triyltris(sulfanediyl)]-tris(2,4-dimethylbenzene). The GC/MS method was found to be useful for the separation of some sulfanyl-substituted butadiene isomer mixtures. The synthesized compounds were characterized by elemental analyses, mass spectrometry, UV-Vis, IR, and NMR (¹H, ¹³C) or fluorescence spectroscopy.     

Diazo reactions with unsaturated compounds: XI. Reactions of benzene-, p-methylbenzene-, and p-methoxybenzenesulfonyl-1,3-butadienes with arenediazonium chlorides and 1-aryl-3,3-dimethyl-1-triazenes

1-(p-Methylbenzene)-and 1-(p-methoxybenzenesulfonyl)-1,3-butadienes in aqueous acetone in the presence of copper(I) or copper(II) chlorides react with arenediazonium chlorides and 1-aryl-3,3-dimethyl-1-triazenes to form 1-(p-methylbenzene)-and 1-(p-methoxybenzenesulfonyl)-4-aryl-3-chloro-1-butenes, respectively. 1-(Benzenesulfonyl)-1,3-butadiene undergoes tarring under the same conditions.     

Uncommon transformations of methyl (1S,2S,3R,4R)-2,3-isopropylidenedioxy-5-iodomethyl-2-tetrahydrofurylacetate initiated by bases

Methyl (1S,2S,3R,4R)-2,3-isopropylidenedioxy-5-iodomethyl-2-tetrahydrofurylacetate prepared in two stages from D-ribose acetonide underwent a series of uncommon transformations under the treatment with bases providing the following different products depending on the base applied: methyl 3-(5-acetyl-2,2-dimethyl-1,3-dioxol-4-yl)propionate (DBU), methyl 2,3-isopropylidenedioxy-7-oxabicyclo[2.2.1]heptane-6-carboxylate (t-BuOK), methyl {(5R)-2,2-dimethyl-5-[(2R)-oxiranyl]-1,3-dioxolan-4-ylidene}propionate and methyl-(E)-3-{(4S,5R)-2,2-dimethyl-5-[(1R)-(2-oxiranyl)]-1,3-dioxolan-4-yl}-2-propenoate (t-BuOK and LDA).     

Zur Synthese und Pyrolyse von Organoelement-benzasolderivaten des Phosphors,Arsens, Siliciums und Zinns

3-Organo-1,3-benzazaphospholes and -benzazarsoles as well as 3,3-disubstituted 1,3-benzazasiloles and -benzazastannoles are prepared from o-LiC₆H₆NC(Li)Bu^t and the relevant organoelement dichlorides. The heterocycles obtained are converted by flash vacuum pyrolysis into the aromatic 1H-1,3-benzazaphospholes and benzazarsoles, respectively.     

Climacostol, a defense toxin of Climacostomum virens (protozoa, ciliata), and its congeners

Climacostol (1), a defense toxin of the heterotrich ciliate Climacostomum virens was established as 5-(Z)-non-2-enyl-benzene-1,3-diol. The structure was rigorously confirmed by the total synthesis. The two congeners of climacostol contained in this ciliate were determined as 5-(Z,Z)-undeca-2,5-dienyl-benzene-1,3-diol (2) and 5-(Z,Z,Z)-undeca-2,5,8-trienyl-benzene-1,3-diol (3).     

Synthesis of conjugated (1E,3E)- and (1Z,3Z)-1,4-di(n-pyridyl) (or n-quinolyl)-1,3-butadienes from n-(2′-chloroethenyl)pyridine (or quinoline)

The homocoupling reaction between the conjugated n-(2-chloroethenyl)pyridine; n, 2-, 3- and 4- (or quinoline; n, 2- and 4-) mediated by zero-valent nickel complexes at room temperature affords to the corresponding 1,4-diaryl-1,3-butadiene, always as the 1E,3E stereoisomer. The yield in 1,4-diaryl-1,3-butadiene increases with the nickel catalyst and hence, the active zero-valent nickel catalyst is not regenerated during the homocoupling reaction.The stereospecific synthesis of (1Z,3Z)-1,4-di(4′-pyridyl)-1,3-butadiene stereoisomer was efficiently carried out by partial hydrogenation of the appropriate 1,4-di(4′-pyridyl)-1,3-butadiyne.     

Highly stereoselective transformation of (1S,3S)-cis-1,3-disubstituted tetrahydro-β-carbolines into (1S,3R)-trans-1,3-disubstituted tetrahydro-β-carbolines: an improved asymmetric synthesis of tadalafil from l-tryptophan

An efficient and general method for the highly stereoselective transformation of (1S,3S)-cis-1,3-disubstituted 1,2,3,4-tetrahydro-β-carbolines (THBCs) into (1S,3R)-trans-1,3-disubstituted THBCs is described. The method contains the following three steps: the enantiomerically pure (1S,3S)-cis-1,3-disubstituted THBCs 1 were first converted into (1S,3S)-cis-1,2,3-trisubstituted THBCs 2 by N-1-naphthylmethylation/benzylation; (1S,3S)-cis-1,2,3-trisubstituted THBCs2 were then converted into (1S,3R)-trans-1,2,3-trisubstituted THBCs 3 in high yields and with high stereoselectivities via a base-catalyzed epimerization at C-3; (1S,3R)-trans-1,2,3-trisubstituted THBCs 3 were subsequently converted into (1S,3R)-trans-1,3-disubstituted THBCs 4 after reductive removal of the 1-naphthylmethyl/benzyl group. In addition, as an application of this method, an improved and highly stereoselective synthesis of the PDE5 inhibitor tadalafil (Cialis®) starting from natural and less expensive l-tryptophan was developed.     

Simple construction of fused and spiro nitrogen/sulfur containing heterocycles by addition of thioamides or thioureas on cycloalkenyl-diazenes: examples of click chemistry

New 1-cycloalkenyl-1-diazenes have been obtained in good yields from cyclic β-ketoesters and hydrazine derivatives. They furnished new cycloalkyl[d][1,3]thiazolines with thioamides or new spirocycloalkyl-thiazolinones with thioureas. Moreover they gave, with imidazolidine-2-thione and tetrahydropyrimidine-2-thione, new and interesting spiro[cycloalkyl-1,2′-imidazo[2,1-b][1,3]thiazole] or spiro[cycloalkyl-1,2′-[1,3]thiazolo[3,2-a]pyrimidine] derivatives, respectively. Cycloalkyl[d][1,3]thiazolines were useful for the further preparation of unknown thia-triaza-tricyclo derivatives. Novel hexahydro-1,3-benzothiazoles have been achieved by reaction of N,N′-dialkylthioureas on N-1-phenyl-2-(1-cyclohexenyl)-1-diazene-1-carboxyamide. The acidic hydrolysis of spirocycloalkyl-thiazolinones produced 2-imino-5-(ω-carboxyalkyl)-4-thiazolidinones.     

Synthesis, structure, and photoisomerization of derivatives of 2-(2-quinolyl)-1,3-tropolones prepared by the condensation of 2-methylquinolines with 3,4,5,6-tetrachloro-1,2-benzoquinone

A series of novel derivatives of the 1,3-tropolone (β-tropolone) system—2-(2-quinolyl)-5,6,7-trichloro-1,3-tropolones and 2-(2-quinolyl)-4,5,6,7-tetrachloro-1,3-tropolones have been prepared by the acid-catalyzed reaction of 2-methylquinolines with 3,4,5,6-tetrachloro-1,2-benzoquinone. The molecular structures of two compounds, 2-(4-chloro-6,8-dimethyl-5-nitro-2-quinolyl)-5,6,7-trichloro-1,3-tropolone 8 and 2-(4-chloro-7,8-dimethyl-5-nitro-2-quinolyl)-4,5,6,7-tetrachloro-1,3-tropolone 9, have been determined using X-ray crystallography. According to the performed DFT B3LYP/6-311++G^∗∗ calculations the tautomeric (OH) and (NH) forms of β-tropolones 8 and 9 are nearly energy equivalent, the latter being more stabilized in polar media. Photolysis of 2-(2-quinolyl)-1,3-tropolones in heptane solution leads to the disrotatory electrocyclic rearrangement resulting in the formation of a mixture of E- and Z-isomers of 3-[2(1H)-quinolinylyden]-bicyclo[3.2.0]hept-6-en-2,4-dione derivatives.     

Synthesis of 3-[2-(1,3-butadienyl)]-1H-indoles en route to murrapanine analogue

A three-step procedure has been developed for the synthesis of 3-[2-(1,3-butadienyl)]-1H-indoles. TBAF was proved to be an effective reagent for dehydrobromination and carbomethoxy deprotection in one step to give 3-[2-(1,3-butadienyl)]-1H-indoles from the corresponding bromo-derivatives. Suitably substituted indolyl-1,3-butadiene has been successfully applied to prepare murrapanine analogue via Diels-Alder reaction.     

An expedient approach for the synthesis of dispiropyrrolidine bisoxindoles, spiropyrrolidine oxindoles and spiroindane-1,3-diones through 1,3-dipolar cycloaddition reactions

A series of dispiropyrrolidine bisoxindoles were synthesized via a multicomponent 1,3-dipolar cycloaddition reaction of isatin, sarcosine and isatylidene malononitrile in refluxing methanol. Also a series of spiropyrrolidine oxindoles and spiroindane-1,3-diones were synthesized using 2-(1H-Indole-3-carbonyl)-3-phenyl-acrylonitrile and 2-(1,3-dioxo-indan-2-ylidene)-malononitrile as dipolarophiles, respectively.     

Molecular structures of methyl 4-[(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)methyl]-1-methyl-1H-pyrazol-5-carboxylate and methyl 4-[(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)methyl]-1-methyl-1H-pyrazol-3-carboxylate

The structure of methyl 4-[(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)methyl]-1-methyl-1H-pyrazol-5-carboxylate is determined by X-ray crystallography and further used to elucidate the structure of methyl 4-[(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)methyl]-1-methyl-1H-pyrazol-3-carboxylate, using the data of homo- and heteronuclear 2D NMR correlation spectroscopy.