Mariusz Krawiec

Tetrathiafulvalene quinones, hydroquinones and esters

Abstract Benzocyclohexa-2,5-diene-1,4-dione-1,3-thiole-2-thione (2) was synthesized starting with 2,3-dichloronapthoquinone (1). Compounds 3 and 4 were also obtained; however, the yield of 2 can be increased through control of the temperature and reaction time. Reaction of 2 with triethylphosphite gave 5 and the tetrathiafulvalene ester 6. The tetrathiafulvalenequinone (9) was obtained by hydrolysis of 6 followed by oxidation of 8. Compound 9 was obtained more directly by hydrogenation of 2 followed by coupling with triethylphosphite and oxidation. Chloranil was used to prepare the dithiafulvene quinone 12 which was reduced, coupled with triethylphosphite to form, presumably , polymer 13. The reactions were repeated using the hexanoic acid esters of the corresponding hydroquinone thiafulvalenes. The crystal structures of 2, 3, 4, 5, 6a and 10 were determined by X-ray diffraction. Cyclic voltammetry studies show the tetrathiafulvalene quinones reduce like quinones, but do not exhibit the oxidation properties of tetrathiafulvalenes.

THIELE'S ACID REVISITED : ISOLATION AND CHARACTERIZATION OF TWO MINOR PRODUCTS FORMED BY CARBONATION OF CYCLOPENTADIENIDE ANION

Abstract Carbonation of sodium cyclopentadienide leads to the formation of 3aα,4α,7α,7aα-tetrahydro-4,7-methano-1H-indene-2,6-dicarboxylic acid [i.e., “Thieles acid”, 2i (R = H), 60%] along with several isomeric C12H12O4 minor products. The dimethyl esters of two of these minor products, i.e., dimethyl 3aα,4α,7α,7aα-tetrahydro-4,7-methano-1H-indene-2,4-dicarboxylate [2a (R = Me), 13%) and the corresponding 3a,6-dicarboxylate [2n (R = Me), 1%] have been isolated and characterized. Intramolecular [2 + 2] photocyclization of 2a (R = Me) afforded 3a (R = Me) (30%), whose structure was established unequivocally by application of X-ray crystallographic techniques.

Eudesmanolides and other constituents of Inula thapsoides

Abstract Three new eudesmanolides, 1β-hydroxy-11α,13-dihydroalantolactone, 1α-hydroxy-11α,13-dihydroalantolactone and 1β,4α-dihydroxy-11α,13-dihydroalantolactone, along with the known compounds sclareol, 7,11,15-trimethyl-3-methylenehexadecan-1,2-diol, β-sitositerol, stigmasterol and stigmasterol 3β-D-glucoside have been isolated from the whole plant extract of Inula thapsoides .

An unusual cycloartane triterpenoid from Cimicifuga foetida

A new cycloartane triterpenoid glycoside has been isolated from the rhizomes of Cimicifuge foetida L. The spectroscopic characteristics of the new compound are different from previously described cycloartane triterpenoids because of the loss of the 24-isopropyl group as well as the presence of a 11 beta-OH group. Based on spectroscopic evidence, including a series of 2D-NMR analyses, the structure of the new triterpene is assigned as 24-des-isopropyl-7-ene-23-one-9,19; 16,24-dicycloart-3 beta,11 beta,16 alpha,24 alpha-tetraol 3-O-beta-D-xylopryanoside, named here as neocimiside. The structure of the aglycone of neocimiside was confirmed by X-ray analysis.

Benzoquinone derived 1,3-dithiole-2-ones and thiones

The syntheses and structures of 1,3-dithiole and tetrathiafulvalene derivatives of benzoquinone have been investigated. This work extends earlier investigations of naphthoquinone analogues. The X-ray structures, NMR, IR, UV, mass spectra, and E01/2 values from cyclic voltammetry measurements are reported.Ab initio STO-6-31G calculations are used to correlate the cyclic voltammetry and UV data for selected compounds.

A guaianolide from Tanacetum argenteum subsp. flabellifolium

Abstract A new guaianolide was isolated from the aerial parts of Tanacetum argenteum subsp. flabellifolium , which is endemic to Turkey. The structure of the new compound was elucidated by spectral methods, including NMR ( 1 H NMR, NOE, APT, DEPT and HETCOR) and X-ray techniques.

Structures of three substituted pentacyclo[5.4.0.02, 6.03, 10.05, 9]undecanes and a computational analysis of bond lengths

Abstract5-Methyl-2-phenylpentacyclo[5.4.0.02, 6.03, 10.05, 9]undecane-8, 11-dione,5-methyl-2-phenylpentacyclo [5.4.0.02,6.03,10.05,9]undecane-8-one-11-ol,and 5-methyl-2-phenylpentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-diol are three cage compounds which differ only in the oxidation state at C(8) and C(11). The three compounds contain a four-membered, a six-membered, and four five-membered rings fused into a cagelike structure. An X-ray structure analysis shows the C(1)-C(7) and C(9)-C(10) bonds in the diketo cage to be 1.606(2) and 1.586(2) Å, which are significantly longer than in the other two molecules. In order to assess the effects of strain, steric, and electronic factors in these compounds, we investigated the unsubstituted parent cage compounds and a series of derivatives by molecular mechanics (MM3), AMPAC (AM1), MOPAC (PM3), and GAUSSIAN 90 calculations. These data suggest that dipolar through space interactions are responsible for the bond elongation and not aπ−→σ* interaction, which has been postulated in parallelπ-systems originating from a common bond. A small degree ofπ−→σ* “through-bond” interaction may contribute to the lengthening in the dimethylene cage analogues.

Synthesis of Novel Heterocyclic Clefts Derived from Tetracyclo[6.3.0.04,11.05,9]undecane-3,6-dione and Tricyclo[6.3.0.02,6]ubdecane-3,11,dione

New molecular clefts dipyridazinotricycloundecane derivatives (6a-6c), (9a), and (9b) have been prepared via base promoted reactions of 3,6-di -aryl-1,2,4,5-tetrazines with tetracyclo[6.3.0.0 4,11 .0 5,9 ]unde- cane-3,6-dione (1) and with tricyclo [6.3.0.0 2,6 ]undecane-3,11-dione (10), respectively. Compounds of this type are of interest as a poten- tial new class of host molecules for use in host-guest complexation studies (i.e., inclusion phenomena and molecular recognition). The re- sults obtained via studies of the solution electrochemistry of systems (6a-6c), (9a), and (9b) afforded no evidence for the existence of any significant electronic interaction between opposing «arms» in these molecular clefts

Structure and properties of transition metal complexes of naphthoquinonedithiolate

Naphthoquinonedithiolate (nqdt) is a “noninnocent” ligand forming dithiolene transition metal complexes. Most [M(nqdt)2]−1 and [M(nqdt)2]−2 complex ions are planar with each forming an isomorphous series with the (n-butyl)4N+ (tba) counter ion. The cobalt complex is isolated as a step dimer (tba)2[Co(nqdt)2]2 where two square-planar monomer units are bonded via Co−S intermolecular interactions.Ab initio andsemi-empirical calculations are used to investigate the complex ions. The complexes form tba single crystals only with difficulty, and an extensive study with ions of various shapes and charges failed to identify a more satisfactory counter ion. The magnetic susceptibilities of four complexes are discussed. The (tba)[Ni(nqdt)2] complex undergoes a weak ferromagnetic transition at 4.43 K while a mixed oxidation state Mn(II) complex exhibits a weak ferromagnetic transition at 40K. The crystal structures of (tba) [Cu(nqdt)2], (tba)[Ni(nqdt)2], (tba)2[Ni(nqdt)2], (tba)2[Pd(nqdt)2], {(tba)[Co(nqdt)2]}2 and four side reaction products 5,7,12,14-tetrahydrodibenzo-[b,i]thianthrene-5,7,12,14-tetraone (2), benzocyclohexa-2,5-diene-1,4-dione-1,3-thiole-2-thione (3), a thiomethyl derivative (4), and an unusual oxidatively coupled product (5) are reported.

Synthesis and chemistry of a facially dissymmetric cage-condensed p-benzoquinone; a synthetic entry into novel doubly-caged systems

Abstract The synthesis of a novel caged quinone, 1, is reported. Diels-Alder cycloaddition of cyclopentadiene to 1 results in the formation of two endo adducts, 2a and 2b, each of which can be photocyclized to the corresponding “doubly-caged” diketone (3a and 3b, respectively).