Ingeborg Csöregh

New trigonal lattice hosts: stoicheiometric crystal inclusions of laterally trisubstituted benzenes—X-ray crystal structure of 1,3,5-tris-(4-carboxyphenyl)benzene·dimethylformamide

New host molecules with a central 1,3,5-trisubstituted benzene ring and rigidly attached lateral arms composed of aryl or arylethynyl and extra functional groups are reported. They are shown to give more than thirty clathrates with a wide variety of organic solvents comprising alicyclic, aromatic, heterocyclic, dipolar aprotic, and protic molecules. Inclusion selectivities and stoicheiometries of the different clathrates are discussed. The crystal structure of (2a)·dimethylformamide (DMF)(1:3) inclusion compound has been determined from single-crystal X-ray diffraction. The crystals show R symmetry. There are six host and eighteen guest molecules in the hexagonal unit cell with a=b= 23.160(9) and c= 11.812(3)A. The final linear R is 0.082 for 1 518 unique reflections. The host molecules adopts a propeller conformation with perfect three-fold symmetry and acts as a donor in hydrogen bonds to three DMF molecules. In the crystal structure the host–guest units are arranged stack-wise.

Inclusion Compounds of Diol Hosts Featuring Two 9-Hydroxy-9-fluorenyl or Analogous Groups Attached to Linear Spacer Units

A series of new clathrate host molecules 1−15, each containing two 9-hydroxy-9-fluorenyl or analogous terminal groups attached to linear central units of different lengths and structural compositions, has been synthesized. Their crystalline inclusion compounds with a variety of organic guests − including amines, alcohols, ketones, and other dipolar aprotic compounds or aromatic hydrocarbons − are reported (229 examples of clathrates) and their properties are compared. The crystal structures of a free host compound and of six selected clathrates of different compound classes have been determined by X-ray diffraction, showing varied modes of supramolecular interaction.

Total synthesis of balanol, part 2. Completion of the synthesis and investigation of the structure and reactivity of two key heterocyclic intermediates

Abstract A convergent enantioselective total synthesis of the natural product (-)-balanol (1) is described. In addition to benzophenone fragment 8, key intermediates are chiral bicyclic aziridine 3 and the corresponding epoxide 4, both of which undergo highly regio- and stereoselective nucleophilic ring-opening reactions, allowing control of the two stereogenic centres of the target molecule. The structure and reactivity of 3 and 4 have been investigated in some detail.

New coordination polymer networks based on copper(II) hexafluoroacetylacetonate and pyridine containing building blocks: synthesis and structural study

The interaction between copper(II) hexafluoroacetylacetonate [Cu(hfacac)2] and pyridine-containing building blocks with linear, angled and trigonal geometry (1–3) has led to isolation of different coordination polymers (A–D). These were studied by infrared spectroscopy and single-crystal X-ray diffraction methods. The copper coordination geometry in the present complexes can be described as a more or less distorted square bipyramid (or elongated octahedron). The unsaturated Cu(hfacac)2 units are connected by the aromatic spacer ligand moieties 1–3 so as to form polymeric frameworks, which are infinite either in one (A and D) or in two dimensions (C). The polymeric ropes or sheets are held together in the crystals by relatively weak intermolecular interactions, in which the protruding fluoro substituents of the metallic links play an active role. The porous compound A was also studied with respect to sensing reactions for potential analysis of selected volatile compounds. The screening shows interesting reactions of this coordination polymer, indicating a reversible response of relatively small and polar analytes such as methanol, ethanol and acetone, but not of water.

Halogen···halogen versus OH···O supramolecular interactions in the crystal structures of a series of halogen and methyl substituted cis-9,10-diphenyl-9,10-dihydroanthracene-9,10-diols1

Abstract The crystal structures of four p-phenyl-substituted cis-9,10-diphenyl-9,10-dihydroanthracene-9,10-diols, carrying chloro- (1), bromo- (2), iodo- (3) and methyl substituents (4), respectively (with 2 being a previously described compound), have been studied in order to compare the effects of these substituents on the crystalline architecture. Ordinary O–H···O hydrogen bonds govern the packing of the methyl-substituted molecules in 4, whereas interhalogen interactions in competition with conventional hydrogen bonds direct the crystalline arrangement of the halogenated homologues 1–3, yielding somewhat lower symmetry and lower packing coefficient for the latter crystals. All short (Cl···Cl

Versatility of the 1,1′-binaphthyl-2,2′-dicarboxylic acid host in solid-state inclusion: crystal and molecular structures of the dimethylformamide (1 : 2), dimethyl sulphoxide (1 : 1), and bromobenzene (1 : 1) clathrates

The clathrate structures of the host 1,1′-binaphthyl-2,2′-dicarboxylic acid (1) with dimethylformamide, (2), dimethyl sulphoxide, (3), and bromobenzene, (4) as guest molecules have been studied. X-Ray structure analyses show that the capacity for inclusion is primarily dependent on the proton donor–acceptor (co-ordinating) ability of the host. Nevertheless, the structures are very different. In (2)[crystal data: a= 14.916 (13), b= 9.882(10), c= 17.128(13)A, β= 90.45(7)°, space group P21/c, Z= 4, Rf= 0.066 for 2 550 observations] the guest molecules can act both as proton donor and acceptor in hydrogen bonding with the host, in (3)[a= 12.912(5), b= 17.979(15), c= 9.702(7)A, β= 110.79(7)°, P21/n, Z= 4, Rf= 0.080 for 1 932 reflexions] the guest molecule acts as proton acceptor only, and in (4)[a= 9.955(2), b= 10.426(3), c= 12.005(3)A, α= 77.34(2), β= 93.02(2), γ= 104.59(2)°, P, Z= 2, Rf= 0.074 for 1 555 observations] a ‘true’ clathrate structure is established, with bromobenzene being incorporated in a hydrogen-bonded host matrix of (1). The decrease in co-ordinating bond strength between host and guest is also manifested in the gradual increase of disorder observed for these guest species. Conclusions concerning the clathrate formation selectivity of (1) are derived from the structural observations.

Simultaneous electrophile–nucleophile Cl⋯π interactions stabilizing solid state inclusions: a new tool for supramolecular crystal engineering

The crystalline inclusions of the host compound trans-11,12-bis[bis(p-chlorophenyl)hydroxymethyl]-9,10-ethanoanthracene, with guests such as pentan-2-ol[1·pentan-2-ol(1:1), 1a], 1,4-dioxane [1·1,4-dioxane (2:5), 1b] and o-xylene [1·o-xylene (1:2), 1c] were shown by X-ray analysis to have host matrices mainly determined by directional ‘electrophile–nucleophile pairing’ interactions, involving a chloro substituent and the adjacent aryl π electrons of a neighbouring molecule. The observed shorter Cl⋯centroid distances in 1a–c are between 3.33 and 3.75 A. On the other hand, the versatility of host–guest interactions due to the different proton donor–acceptor abilities and polarities of the guests yielded various packing relations with different symmetries and conformations of the host hydroxy functions. Although compounds 1a and 1b contain H-bonded 1·pentanol and 1·dioxane aggregates, respectively, the realized packing arrangements seem to be a compromise between close packing on the one hand and hydrogen bonding on the other. Compound 1c is a lattice-type inclusion in which the o-xylene guests are trapped in tunnels formed by the bulky host molecules.

Large scale synthesis and absolute configuration of (-)-3-ppp, a selective dopamine autoreceptor agonist

Abstract A large scale synthesis for (-)-3-PPP has been developed. The racemic methoxy compound 1 was prepared in a three step procedure in 63% yield. This was resolved as a diastereomeric salt by crystallization of the (-)-di-p-toluoyltartrate. Two crystallizations gave the pure (-)-enantiomer 2 in 50% of the theoretical yield and with an enantiomeric excess of >95%. Demethylation using aqueous HBr gave (-)-3-PPP, ( 3 ). Compound 2 was also prepared in a stereoselective synthesis from S -(-)- N-propyl-2- chloromethylpyrrolidine 4 . By X-ray crystallography it was shown that (-)-3-PPP has the S -configuration at the chiral carbon.

The chemical-transformation products of 1,6-dibromo-1,6-dideoxygalactitol and 1,2: 5,6-dianhydrogalactitol in aqueous solution

Abstract After hydrolysis of 1,6-dibromo-1,6-dideoxygalactitol ( 1 ) and 1,2:5,6-dianhydrogalactitol ( 2 ), 11 compounds were isolated, three of them as tritylated derivatives. Their structures were established on the basis of chemical evidence and, for four compounds, by X-ray diffraction. The main product of the hydrolysis of 1 was 3,6-anhydro-1-bromo-1-deoxy- dl -galactitol; the end-products of the hydrolysis of 2 were 1,5-anhydro- dl -galactitol, 2,5-anhydro- dl -altritol, and galactitol.

Selectivity and reactivity in asymmetric allylic alkylation

Hydroxyalkyl)-6-oxazolyl-and 2-(1-alkoxyalkyl)-6-oxazolylpyridines serve as versatile ligands in the palladium-catalyzed allylic substitution of rac-1,3-diphenyl-2-propenyl acetate with dimethyl malonate as nucleophile. The enantioselectivity of the reaction is dependent on the conformation of the ligands, as deduced by NMR, X-ray crystallography and DFT calculations of palladium(II) complexes of the ligands. The reactions are slow, requiring up to four days reaction time. However, with the use of microwave flash heating, reaction times are reduced to 2 min, with only minor loss in stereoselectivity.