Substituent effect on cyclopalladation of arylimines

The substituent effect on cyclopalladation of a series of substituted benzylidene-arylamines [(R₂C₆H₃)NCCH₂(ArX_n), where R=H, Me, i-Pr, OH; X_n=H; 3,5-dimethoxyl; 3,5-difloro; 3,5-bis(2,6-dimethoxyphenyl); 4-chloro; 2-bromo; 2,4,6-trimethyl] by palladium(II) chloride under basic conditions was studied. As expected, cyclometallation takes place at the ortho position of the aryl ring resulting in formation of a five-member chelate ring. All metallated products have in chloro-bridged dipalladium [Pd₂Cl₂] structures except the one with R=OMe. A palladium species with mixed bridging ligand [Pd₂(OH)Cl] was isolated due to the hydrogen-bonding interaction through the hydroxy ligand and the methoxy substituents. For the t-butyl substituted arylimine, cyclometallation does not occur because of the steric reason. In the case of R=OH, X_n=2,4,6-trimethyl, the cyclopalladation occurred at the benyzlic position forming a tetrameric palladium species. All the palladium complexes were characterized by both spectral and/or crystal structural analyses.     

X-ray structural investigation of gossypol and its derivatives XX. Structure of the solvate of gossypol with pyridine

The structure of the solvate of gossypol with pyridine has been determined by x-ray structural analysis. The crystalline solvate is a H-clathrate with the channel type of structure in which there are three pyridine molecules to each host molecule. On the desolvation of gossypol tripyridine, a new polymorph is formed.Communications (XI–XIX) are represented by the publications given in the Literature Cited under Nos. 1–9.Institute of Bioorganic Chemistry, Uzbekistan Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 186–191, March–April, 1992.     

X-ray structural investigation of gossypol and its derivatives XXII. Structure of the H-clathrate of gossypol with dimethyl sulfoxide

In crystals obtained from solutions in DMSO, gossypol molecules are again present in the aldehyde tautomeric form. These crystals are H-clathrates with the channel type of structure which has much in common with the structure of the complexes of gossypol with methanol and with formic acid.Institute of Bioorganic Chemistry, Uzbekistan Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, Nos. 3,4, pp. 330–334, May–August, 1992.     

X-ray structural investigation of gossypol and its derivatives XXV. Structure of the clathrate of gossypol with isopropyl alcohol

With isopropyl alcohol, gossypol forms a clathrate isostructural with the complexes of gossypol formed by ketones (acetone), aldehydes (butyraldehyde),or alcohols (propyl alcohol). The hydroxy group of isopropyl alcohol acts as the proton acceptor in a hydrogen bond of the host-guest type.A. S. Sadykov Institute of Bioorganic Chemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 62 70 71. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 220–225, March-April, 1995. Original article submitted September 6, 1994.     

Inclusion complexes of the natural product gossypol. Recognition by gossypol of halogeno methanes. Structure of the dichloromethane complex of gossypol and single crystal conservation after decomposition

The structures of gossypol complexes are extremely sensitive to the halogenomethane present as the guest; e.g. changing the number of Cl atoms in chloromethane derivatives changes the structure of the gossypol complex. The crystals of C₃₀H₃₀O₈·CH₂Cl₂ are monoclinic, space groupC2/c,a=21.320(4),b=19.199(6),c=15.765(2)Å, =113.05(2)^o,V=5916(2)ų,Z=8,D _x=1.35 g/cm³,T=295 K. The structure has been solved by direct methods and refined to the finalR value of 0.084 for 1828 reflections. In the structure H-bonded gossypol molecules form columns, generating channels in the structure which are filled by guest molecules. After decomposition (desolvation) monocrystals of the complexes are conserved without destruction, in which there are rather wide and empty channels though slightly smaller than in the complex. An attempt is made to explain some peculiarities of the behavior of the gossypol polymorph formed on the basis of its structure with empty channels. Supplementary data relevant to this article have been deposited with the British Library Publication No. SUP 82165 (17 pages).     

Selective conversion of diallylanilines and arylimines to quinolines

A variety of diallylanilines are shown to undergo cobalt-carbonyl catalyzed rearrangement to quinolines. Diallylanilines are also used as allyl transfer reagents to convert benzaldimines into quinolines. Substitution in the 2- and 3-positions of the quinoline is featured in all transformations.     

Gossypol clathrates: Structure and thermal behavior of the gossypol acridine complex

The natural compound gossypol forms a stable clathrate with acridine. The composition of the clathrate is C₃₀H₃₀O₈·0.5C₁₃H₉N. The unit cell is monoclinic, C2/c space group, a = 11.3213(3) ?, b = 30.5957(13) ?, c = 17.0824(4) ?, γ = 94.153(2)°, V = 5901.5(3) ?³, M = 1153.24, Z = 8, d _x = 1.369 g/cm³, and R = 0.0413 for 4726 reflections. The structure of the clathrate allows one to refer this compound to the ethyl acetate isomorphic host-guest group of gossypol complexes.     

Extraction of gossypol

The conditions for the extraction of gossypol from cottonseed flakes and from isolated gossypol glands have been investigated. It has been established that the amount of gossypol extracted by hexane is affected mainly by the degree of stirring, the moisture content, the material, and the temperature. By steeping the flakes first with concentrated miscella and then with hexane it is possible to extract about 60–65% of the gossypol. It has been shown that hexane and miscella extract practically no gossypol either from dry or from moistened gossypol glands, and only acetone extracts it almost completely.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 157–160, March–April, 1980.     

New gossypol imines

Information is given on new gossypol imines. The use of hydrazines as the imine components produces Schiff bases of gossypol existing in the benzoid form.A. S. Sadykov Institute of Bioorganic Chemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 62 70 71. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 703–706, September–October, 1997.     

Tetrathiafulvalene–oxazoline ligands in the iridium catalyzed enantioselective hydrogenation of arylimines

Cationic iridium complexes based on enantiomerically pure tetrathiafulvalene–oxazoline ligands have been used in the asymmetric hydrogenation of N-(phenylethylidene)aniline. Complete conversions with ee’s up to 68% could be reached in the case of the TTF–phosphinooxazoline (TTF–PHOX) ligands.     

Gossypol clathrates: Structure and thermal behavior of gossypol solvates with two picoline isomers

Gossypol forms stable solvates with 4- and 2-picolines at room temperature. The solvates are investigated by single crystal X-ray diffraction and thermal analysis. Solvate crystals of gossypol with 4-picoline (1) have the 1:3 composition (gossypol:4-picoline) and crystallize in the P2₁/c space group. This substance is isostructural to a trisolvate of gossypol with pyridine. Solvate crystals of gossypol with 2-picoline (2) have the 1:4 composition (gossypol:2-picoline) and crystallize in the P-1 space group. The unit cell parameters for the investigated structures are as follows: 1 monoclinic crystals, C₃₀H₃₀O₈·3C₆H₇N, a = 10.7530(1) ?, b = 20.7834(3) ?, c = 19.1166(2) ?, β = 95.537(1)°, V = 4252.32(9) ?³, M = 797.92, Z = 4, d _x = 1.246 g/cm³, and R = 0.0489 for 4102 reflections; 2 triclinic crystals, C₃₀H₃₀O₈·4C₆H₇N, a = 11.467(1) ? b = 14.962(2) ?, c = 15.570(3) ?, α = 75.62(1)°, β = 69.83(1)°, γ = 79.58(1)°, V = 2414.6(7) ?³, M = 891.04, Z = 2, d _x = 1.226 g/cm³, and R = 0.0528 for 3779 reflections. The results of the single crystal XRD and thermal analysis confirm that gossypol with 4-picoline forms a trisolvat, and a tetrasolvate with 2-picoline. The transition from 4-picoline to 2-picoline proves to change the type of the host-guest association from one-dimensional to zero-dimensional, i.e., to lead to a new crystal structure. Desolvation of compound 2 begins at a lower temperature than that for compound 1, which is explained by their different crystal structures. Keywords: gossypol, 4-picoline, 2-picoline, clathrate formation, crystal structure.     

Determination of gossypol solubility

To improve the extraction of gossypol from the cotton seeds, the solubility of gossypol in different solvents and at different concentrations of micelles was studied. Petroleum ether, hexane, and extraction benzol were used as solvents. Model micelles were prepared from the cotton oil free of gossypol; concentration of micelles ranged from 0 to 50%. Pure gossypol was added to the micelles in the amount sufficient for formation of saturated solution. The solution was then heated to a temperature close to the boiling point of the respective solvent for 10 minutes. The undissolved gossypol was then filtered off, washed and degreased with petroleum ether, dried and weighed. The amount of dissolved gossypol was determined by the difference between the initial and remaining amounts. Solubility of gossypol in the micelles was found to rise with the increase in the oil content. The solubility grew with the increase in the boiling point of a solvent. At micelles concentrations of 0-25%, solubility of gossypol increased in proportion to the increase in oil concentration. Further increase in the concentration resulted in marked rise in solubility, which reached 2.83% in the pure oil.