Efficient Synthesis of 2,4-Bis(phenyl)-1,3-diselenadiphosphetane-2,4-diselenide (Woollins' Reagent).

An improved approach for the preparation of 2,4-bis(phenyl)-1,3-diselena-2,4-diphosphetane-2,4-diselenide (Woollins' reagent) is described. Reacting dichlorophenylphosphine with Na2Se which was in situ prepared from the reaction of elemental selenium and metal sodium in the presence of naphthalene in refluxing tetrahydrofuran generated Woollins' reagent with excellent purity and a yield of up to 96.4%.

Synthesis and Single Crystal Structures of N-Substituted Benzamides and Their Chemoselective Selenation/Reduction Derivatives.

A series of N-aryl-N-(2-oxo-2-arylethyl) benzamides and cinnamides has been prepared. The reaction of the benzamides with Woollins' reagent, a highly efficient chemoselective selenation/reduction reagent, gave the corresponding N-aryl-N-(arylenethyl) benzoselenoamides in good yields. Five representative single crystal X-ray structures are discussed.

Novel Five- and Six-Membered Rings of Phosphorus-Selenium Heterocycles from Selenation of Amido-Schiff Bases.

Woollins' reagent, [2,4-bis(phenyl)-1,3-diselenadiphosphetane-2,4-diselenide], serving as a selenating-reductive cycloaddition reagent, reacts with nonconjugated amido-Schiff bases to give the corresponding six-membered 1,3,4-selenadiazoles via a ring-expansion accompanied by an additional selenation/cyclization to the imine bond and C=O group; meanwhile, under the same reaction conditions, the selenation of conjugated amido-Schiff bases leads to a series of fused heterocycles with two five-membered rings. Eight single-crystal X-ray structures confirming the formation of these five- and six-membered heterocycles are discussed.

Diverse Derivatives of Selenoureas: A Synthetic and Single Crystal Structural Study.

Reacting aroyl chlorides with an equivalent of potassium selenocyanate, followed by treating with an equivalent of 1,2,4-tri-tert-butylaniline at room temperature, resulted in the expected selenoureas and unusual diselenazoles. The selenation of selenourea by Woollins Reagent gave a new selenoformamide. Nucleophilic addition of selenoureas with acyl bromides led to the formation of new carbamimidoselenoates rather than the expected 1,3-selenazoles. The novel compounds prepared were characterised spectroscopically and crystallographically.

Phosphorus-Sulfur Heterocycles Incorporating an O-P(S)-O or O-P(S)-S-S-P(S)-O Scaffold: One-Pot Synthesis and Crystal Structure Study.

A new one-pot preparative route was developed to synthesize novel organophosphorus-sulfur heterocycles via the reaction of the four-membered ring thionation reagent [2,4-diferrocenyl-1,3,2,4-diathiadiphosphetane 2,4-disulfide (FcLR, a ferrocene analogue of Lawesson's reagent)] and alkenyl/aryl-diols and I2 (or SOCl2) in the presence of triethylamine. Therefore, a series of five- to ten-membered heterocycles bearing an O-P(S)-O or an O-P(S)-S-S-P(S)-O linkage were synthesized. The synthesis features a novel application of the multicomponent reaction, providing an efficient and environmentally benign method for the preparation of the unusual phosphorus-sulfur heterocycles. Seven representative X-ray structures confirm the formation of these heterocycles.

Synthesis and Single Crystal Structures of Substituted-1,3-Selenazol-2-amines.

The synthesis and X-ray single crystal structures of a series of new 4-substituted-1,3-selenazol-2-amines is reported. The efficient preparation of these compounds was carried out by two-component cyclization of the selenoureas with equimolar amounts of α-haloketones. The selenoureas were obtained from the reaction of Woollins' reagent with cyanamides, followed by hydrolysis with water. All new compounds have been characterized by IR spectroscopy, multi-NMR (¹H, 13C, 77Se) spectroscopy, accurate mass measurement and single crystal X-ray structure analysis.

One-Pot Three-Component Condensation Synthesis and Structural Features of Organophosphorus-Sulfur Macrocycles.

A new preparative route was developed to synthesize new phosphorus-sulfur [SP(═S)S moiety]-containing macrocycles via a one-pot and three-component domino reaction of four-membered ring thionation reagents such as 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide (LR, Lawesson's reagent) and 2,4-diferrocenyl-1,3,2,4-diathiadiphosphetane 2,4-disulfide (FcLR, a ferrocene analogue of Lawesson's reagent) and alkyldithiols(aryldithols) and dihaloalkanes in the presence of sodium hydride. Therefore, a series of 12- to 18-membered macrocycles incorporating two phosphorus and six sulfur atoms were synthesized. The synthesis features a novel application of the multicomponent reaction, providing an efficient route to the preparation of the new phosphorus-sulfur-containing macrocycles. Seven representative X-ray structures confirm the formation of these macrocycles and show the presence of a number of the intramolecular C-H···S hydrogen bonding, intermolecular C-H···S, C-H···Cl, and Cl···Cl short contacts and π-stacking interactions in their 3D network structures.

One-Pot Approach to Organo-Phosphorus-Chalcogen Macrocycles Incorporating Double OP(S)SCn or OP(Se)SeCn Scaffolds: A Synthetic and Structural Study.

The development of new methodology for the preparation of functional macrocycles with practical applications is an important research area in macromolecular science. In this study, we report a new one-pot route for the synthesis of a series of macro-heterocycles by incorporating two phosphorus atoms and two chalcogen atoms and two oxygen atoms (double OP(S)SCn or OP(Se)SeCn scaffolds). The three-component condensation reactions of 2,4-diferrocenyl-1,3,2,4-diathiadiphosphetane 2,4-disulfide (FcLR, a ferrocene analogue of Lawesson's reagent) or 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide (LR, Lawesson's reagent), or 2,4-diphenyl-1,3,2,4-diselenadiphosphetane 2,4-diselenide (WR, Woollins' reagent), disodium alkenyl-diols, and dihalogenated alkanes are performed, giving rise to soluble and air or moisture-stable macrocycles in good-to-excellent yields (up to 92 %). This is the first systemically preparative and readily scalable example of one-pot ring opening/ring extending reaction of three-components to prepare phosphorus-chalcogen containing macrocycles. We also provide a systematic crystallographic study.

Novel Fluorinated Phosphorus-Sulfur Heteroatom Compounds: Synthesis and Characterization of Ferrocenyl- and Aryl-Phosphonofluorodithioic Salts, Adducts, and Esters.

A series of novel ferrocenyl- and aryl-phosphonofluorodithioic salts, adducts, and esters has been prepared. The reaction of 2,4-diferrocenyl-1,3,2,4-diathiadiphosphetane 2,4-disulfide {[FcP(µ-S)S]2, FcLR} with dry KF or tetrabutylammonium fluoride (TBAF) led to the corresponding potassium and tetrabutylammonium salts of ferrocenyldithiofluorophosphinic acids. Treating potassium ferrocenyldithiofluorophosphinic acid with an equimolar amount of tetraphenylphosphonium chloride readily yielded the corresponding organic adducts, and with mono- and di-halogenated alkanes generated a series of the corresponding esters of ferrocenylphosphonofluoridodithioates. Similarly, using 1,3-epithionaphtho[1,8-cd][1,2,6] oxadiphosphinine 1,3-disulfide or Belleau's Reagent in place of FcLR resulted in the corresponding novel salts, adducts, and ester derivatives. All new compounds have been characterized by means of multi-NMR (1H, 13C, 31P, 19F) spectroscopy and accurate mass measurement in conjunction with single crystal X-ray crystallography of four structures.

2,4-Diaryl-1,3-chalcogen azoles bearing pentafluorosulfanyl SF5 groups: a synthetic and structural study.

A series of new 2,4-diaryl-1,3-chalcogen azoles having pentafluorosulfanyl SF5 functional groups has been prepared by means of the two-component cyclization of the selenoamide or thioamide with α-bromoketones. The selenoamides or thioamides were obtained from the reaction of Woollins' reagent or Lawesson's reagent with 4-pentafluorosulfanylbenzonitrile, followed by hydrolysis with water. All new compounds were characterized by (1)H, (13)C, (77)Se, (19)F NMR spectroscopy, and accurate mass measurement. X-ray crystal structure analysis of the selenoamide, thioamide, and 2,4-diarylpentafluorosulfanyl-1,3-chalcogen azoles reveal that the selenoamide and thioamide have very similar structural features along with similar intermolecular interactions such as the π-π stacking and the weak N-H···E (E = S or Se) hydrogen bonding. The 2,4-diarylpentafluorosulfanyl-1,3-chalcogen azoles show the newly formed five-membered N(1)-C(2)-E(3)-C(4)-C(5) ring is either perfectly planar (and coplanar with two peripheral aryl ring planes) or near-planar. The π-π intermolecular interactions and the weak C-H···π and C-H···X (X = Br, F, O) hydrogen bonding are discussed in the cases of 2,4-diarylpentafluorosulfanyl-1,3-chalcogen azoles.

Fluorinated phosphorus-selenium heteroatom compounds: phenylphosphonofluorodiselenoic salts, adducts, and esters.

2,4-Bis(phenyl)-1,3-diselenadiphosphetane-2,4-diselenide, [PhP(Se)(µ-Se)]2, Woollins' reagent (WR), reacts with dry KF or tetrabutylammonium fluoride (TBAF) at room temperature generating the corresponding potassium and tetrabutylammonium phenyldiselenofluorophosphinates 1 and 2 in almost quantitative yields. Treating 1 with equimolar amounts of tetraphenylphosphonium chloride or 1,3-dimesityl-1H-imidazol-3-ium chloride in THF at room temperature afforded the corresponding organic adducts 3 and 4 in 90% and 87% yields. Reaction of 1 with mono- and dihalogenated alkanes gave a series of esters of phenylphosphonofluoridodiselenoates 5-8 and 9 in 79-93% yields. Two representative crystal structures are reported.

An efficient route for the synthesis of phosphorus-selenium macro-heterocycles.

Four-membered ring [PhP(Se)(µ-Se)]2 (Woollins' reagent, WR) reacts with disodium alkenyl-diols followed by in situ ring-closure reaction with appropriate dibromoalkanes affording a series of unusual nine- to fifteen-membered organoselenophosphorus macrocycles bearing the O-P-Se-Cn-Se-P-O or O-P-Se-Cn-O-P-Se linkage.

2,5-Diaryl-1,3,4-selenadiazoles prepared from Woollins' reagent.

Two polymorphs of 2,5-diphenyl-1,3,4-selenadiazole, C(14)H(10)N(2)Se, denoted (Ia) and (Ib), and a new polymorph of 2,5-bis(thiophen-2-yl)-1,3,4-selenadiazole, C(10)H(6)N(2)S(2)Se, (IIb), form on crystallization of the compounds, prepared using Woollins' reagent (2,4-diphenyl-1,3-diselenadiphosphetane 2,4-diselenide). These compounds, along with 2-(4-chlorophenyl)-5-phenyl-1,3,4-selenadiazole, C(14)H(9)ClN(2)Se, (III), and 2-(furan-2-yl)-5-(p-tolyl)-1,3,4-selenadiazole, C(13)H(10)N(2)OSe, (IV), show similar intermolecular interactions, with π-π stacking, C-H...π interactions and weak hydrogen bonds typically giving rise to molecular chains. However, the combination of interactions differs in each case, giving rise to different packing arrangements. In polymorph (Ib), the molecule lies across a crystallographic twofold rotation axis, and (IV) has two independent molecules in the asymmetric unit.

Bis(furan-2-ylcarbon-yl) diselenide.

The title mol-ecule, C(10)H(6)O(4)Se(2), lies on a twofold rotation axis. The Se-Se bond length of 2.305 (3) Šis similar to that in diphenyl diselenide [2.3066 (7) and 2.3073 (10) Šfor the P and M isomers, respectively] and longer than that in 1,8-diseleno-naph-thalene [2.0879 (8) Å]. The mol-ecule adopts a gauche conformation with respect to the C=O groups.

2-(4-Fluoro-phen-yl)-3-methyl-1H-indole.

The indole N-H hydrogen in the title compound, C(15)H(12)FN, does not display classical hydrogen bonding. Rather it forms an interaction with the π system of an adjacent indole, resulting in weakly inter-acting chains along the [001] direction.

Phen-yl(2,4,5-triphenyl-cyclo-penta-1,4-dien-1-yl)methanone.

The title compound, C(30)H(22)O, does not form face-to-face π-π inter-actions despite the presence of four phenyl rings within the compound. Instead weak C-H⋯π inter-actions occur between adjacent mol-ecules, with C⋯C contact distances in the range 3.633 (4)-3.974 (4) Å. The ketone O atom also takes part in a weak C-H⋯O inter-action. The three pendant phenyl rings are twisted relative to the central cyclopentadiene ring by 17.82 (17), 29.63 (14) and 61.57 (9)°, while the phenylmethanone is nearly orthogonal, the angle between planes being 87.77 (9)°.

2-Phenyl-5-(p-tol-yl)-1,3,4-oxadiazole.

The title compound, C(15)H(12)N(2)O, adopts the expected near-planar geometry, the phenyl and tolyl rings being inclined relative to the oxadiazole ring by 3.8 (3) and 8.3 (2)°, respectively. This allows adjacent mol-ecules to pack in a parallel fashion and form stacking along [010] via π-π inter-actions [centroid-centroid distances = 3.629 (2) and 3.723 (2) Å]. Further inter-molecular inter-actions include C-H⋯π inter-actions and weak C-H⋯N hydrogen bonds, giving rise to a crossed herringbone packing motif.

2,4,5-Triphenyl-1,3,2-dioxa-phospho-lan-2-one.

The dioxaphospho-lane ring in the title compound, C(20)H(17)O(3)P, adopts an envelope conformation about one of the ring carbons. The benzene rings of the compound do not form face-to-face π-π inter-actions, instead weak C-H⋯π inter-actions occur between adjacent mol-ecules. The methine H atoms on the dioxaphospho-lane ring form weak C-H⋯O hydrogen bonds to the oxide group of an adjacent mol-ecule.

Synthesis of novel 2,5-diarylselenophenes from selenation of 1,4-diarylbutane-1,4-diones or methanol/arylacetylenes.

Reaction of 2,4-bis(phenyl)-1,3-diselenadiphosphetane-2,4-diselenide [PhP(Se)(mu-Se)](2) (Woollins' reagent, WR) with one equivalent of 1,4-diarylbutane-1,4-diones 1a-g in refluxing toluene affords the corresponding 2,5-diarylselenophenes 2a-g in excellent yields (up to 99%). Alternatively, the 2,5-diarylselenophenes (2a and 2b) can be obtained in 70-80% yields from the reaction of arylacetylene with an equivalent of O-methyl Se-hydrogen phenylphosphonodiselenoate; the latter was derived from WR and methanol. The first X-ray structure of 2,5-diarylselenophenes is presented along with characterisation of their redox properties.