Band 40, Heft 5

The thioarsenate(III) Cs 2 As 8 S 13 has been prepared by the reaction of Cs 2 CO 3 with As 2 S 3 in aqueous solution under pressure at 180 °C. Its structure has been established by X-ray structural analysis. The polymeric anion (As 8 S 13 2- ) n is composed of individual As 4 S 4 -rings, which are each connected to three further eight-membered rings via As-S-As bridges, so giving rise to an infinite layer structure.

Hydroxylamine reacts with acrylic acid via a triple Michael-addition forming the 3,3-bis-[2-carboxyethyl]-3-hydroxyaminopropionic acid betain (C 9 H 15 NO 7 ). The crystal and molecular structures have been determined by X-Ray methods (P2 1 /n; a = 8.097(2), b = 9.343(3), c = 14,647(4) Å, β= 91.35(3)°, Z = 4).

The 1-dimethylaminothiabenzene-l-oxides 5a-d are obtained by the reaction of the 2-propy-nones 2a-d with methyl-dimethylamino-oxosulfonio methanide 3 and subsequent treatment of the mixture with t-BuOK. The bonding properties of 5a-d are discussed by comparison of their IR, 1 H and 13 C NMR data with those of the already known 1-methylthiabenzene-1-oxides 6a-d.

SDMA, according to 27 AI NMR almost uniform in benzene, is increasingly disproportionated in the presence of donors in the following order: C 6 H 6 Bu 2 O ≤ Et 2 O ≤ anisole < dioxane ≪ THF < monoglyme ≤ diglyme to the NaAlH 4-x (OCH 2 CH 2 OCH 3 ) x compounds; the structure in solutions is represented by an open-chain oligomer with four-coordinated Na and Al atoms and with Na + autocomplexed by two bidentate -OCH 2 CH 2 OCH 3 ligands belonging to two neighbouring Al Atoms.

The results of the Vilsmeier-Haack-Arnold-reaction with β-4-Dimethylamino-desoxybenzoins are not the expected chloro-formyl-stilbene derivatives but 4-dimethylamino-α-chloro-stilbenes. These compounds undergo a [2+2]photocycloaddition reaction in solid state or fixed on a cellu-lose matrix yielding unstable substituted dichlorotetraphenyl-cyclobutane derivatives, which spontaneously eliminate two molecules of HCl in a following thermal reaction. In this way coloured species - cyanine dyes with a bridged polymethine chain - are formed.

The reaction between AgAsF 6 and phenylphosphine proceeds with formation of a phosphorus-phosphorus bond. The main product 1, [(C 6 H 5 )PH 2 Ag{μ-(C 6 H 5 PH) 2 }] 2 (AsF 6 ) 2 , was characterized by an X-ray structure determination [P1̄, a = 919.0(4), b = 1109.8(4), c = 1316.4(5) pm, α = 97.48(3), β = 107.25(3), γ = 102.71(3)°, Z = 1, R = 0.057 for 2806 observed reflections], 1 contains Ag 2 P 4 rings; the silver atoms are further coordinated by phenylphosphine ligands, thus acquiring trigonal coordination geometry. A similar reaction is observed with Cu(AsF 6 ) 2 , forming the analogous Cu(I) complex 2.

The homocyclic oxides S 9 O (m.p. 33 °C, dec.) and S 10 O (m.p. 51 °C, dec.) have been prepared by oxidation of the corresponding sulfur rings S 9 and S 10 , respectively, by trifluoroperoxy acetic acid (molar ratio 1:2-3) in a carbon disulfide/methylene chloride mixture. According to infrared and Raman spectra, both compounds contain an exocyclic oxygen atom. S 9 O and S 10 O decompose at 25 °C to give SO 2 and a polysulfuroxide S n O with >10 but both can be stored at -78 °C without decomposition. The SS bond distances are discussed on the basis of the Raman spectra. In addition, the Raman spectrum of solid S 9 has been recorded for the first time. It shows that S 9 crystallizes as two allotropes (α-and β-S 9 ) both consisting of cyclic molecules of either C 1 or C 2 symmetry with bond distances of between 203 and 209 pm.

The sterically congested disilanes tBu 2 XSiSiXMes 2 [X = H (1), X = Cl (2)] have been prepared. An X-ray structure analysis of 1 reveals a preference for the anti-conformation in the solid state. Similar results have been obtained by empirical force field calculations and DNMR spectroscopy. Reaction of 2 with an electron rich olefin leads to a chlorine bridged disilanyl radical whereas treatment with alkali metals yields the corresponding disilenyl radical anion, tBu 2 Si=SiMes 2 ˙̄.

Synthesis and properties of the new nickel(I) complexes (COD)Ni(TPP)I (3) and (TCP)Nil (5) are reported. Reaction of 3 and 5 with diphenylacetylene (7) yields alkyne complexes (R 3 P)NiI(PhC 2 Ph)Ni(R 3 P)I (R = Ph (8a), and Cy (8b)). In solution, 3 disproportionates to give nickel(O) and (TPP) 3 Ni 3 I 4 (12)), the structure of which has been determined by X-ray crystallography. Cluster compound 12 is cleaved into monomeric units by addition of ligands such as TPP or CO (TPP = triphenylphosphine, TCP = tricyclohexylphosphine, COD = 1,5-cyclooctadiene).

The phase-transfer-catalytically in situ generated dihalocarbenes CCl 2 and CBr 2 are inserted into a β-C-H bond of the five-and six-membered phosphamanganacycloalkanes (OC) 4 [xxx] (1a, b) [n = 1(a), 2(b)] to give the functionalized metallacycles (OC) 4 [xxx](2a, a′, b, b′) [X = Cl: n = 1(a), 2(b); X = Br: n = 1(a′), 2(b′)]. 2b crystallizes in the orthorhombic space group Pbca with Z = 8 and has a distorted chair conformation with equatorial position of the CHCl 2 group. The envelope conformation of 2a in solution was elucidated by means of 1 H and 13 C{ 1 H} NMR spectroscopic investigations.

Bis(triethylphosphine)(η 4 -tetraphenylcyclobutadiene)nickel (4) was synthesized by the reduction of (η 4 -tetraphenylcyclobutadiene)nickel(II)bromide (3) with t-butyllithium in the presence of Et 3 P, and its structure was determined by X-ray crystallography. Furthermore, its reactivity towards CO, CH 3 CO 2 H, PhC≡CPh, LiAlH 4 and O 2 were investigated. 1,1-Bis(triethylphos-phine)-2,3,4,5-tetraphenylnickelole (14) was synthesized from (E,E)-1,4-dilithio-1,2,3,4-tetraphenyl-1,3-butadiene (15) and bis(triethylphosphine)nickel(II)bromide. Since the resulting crystals of the nickelole were not suitable for X-ray structure determination, the compound was characterized by elemental analyses, spectral data and carbonylation to yield tetraphenylcyclo-pentadienone (6). Analogous reductions of (η 4 -tetraphenylcyclobutadiene)nickel(II)bromide (3) in the presence of Ph 3 P or Ph 2 PCH 2 CH 2 PPh 2 , followed by carbonylation, led to 6 in 40% yield, demonstrating that about half of the cyclobutadiene rings in 3 undergo cleavage upon reduction to give the nickelole. Reactions of the dilithium reagent 15 with NiBr 2 complexed with Me 2 PCH 2 CH 2 PMe 2 ,Ph 3 P or Et 2 PCH 2 CH 2 PEt 2 , led to the formation of thermolabile nickeloles, as demonstrated by carbonylàtion which yielded 6. Warming of the nickeloles and subsequent treatment with CH 3 CO 2 H led to the formation of 1,2,3,4,5,6,7,8-octaphenyl-1,3,5,7-octatetraene (8) and, in one case, octaphenyl-cyclooctatetraene (5). The relevance of these findings to the mechanism of the Reppe nickel-catalyzed oligomerization of alkynes is discussed.

2,2-Dimethyl-5H-pyrano(3,2-c)-l-benzopyrano-5-one(2) and 4H-2,3-dihydro-3-methyl-2-methylene-furan-1-benzopyran-4-one (3), two new coumarin derivatives were synthesised from 4-hydroxycoumarin by treating with 3-chloro-3-methylbut-1-yne and 3-chlorobut-1-yne respectively, both reactions progressing via the phase-transfer catalysis.

Reaction of 3-benzylthiopregna-3,5-dien-20-one or of pregna-3,5-dien-20-one with W-2 Raney nickel in acetone afforded a mixture of 20-ketopregnanes with different degrees of insaturation on rings A and B, of which the main component was identified as pregn-2-en-20-one. When deactivated Raney nickel was used, the main product was the expected pregna-3,5-dien-20-one with minor amounts of pregn-4-en-20-one and pregn-5-en-20-one.

Lithium 4-thiobutadiynides, Ethynylation, Diacetylenic Thioethers By the reaction of (3,4,4-trichloro-3-buten-1-ynyl)thioethers 2 or of (pentachloro-1,3-butadienyl)thioethers 4 with the twofold or the threefold equimolar amount of n-butyllithium the corresponding lithium butadiynides 5 are prepared. The treatment of these acetylides 5 with water, with the halides of some organyl groups or with chloral, phenylisocyanate, cyclohexyl-isothiocyanate and water furnishes the (butadiynyl)thioethers 6 a-f and 7 a-c. The reaction of the lithium butadiynide 5 a with cyanogen bromide and morpholine leeds via the bromoacetylene 8 to the (4-morpholinobutadiynyl)phenylthioether 9.

Starting from the 2-trichloromethyl-thiazolidinones 3 and 4 syntheses of the 2-dichloromethy-lene-4-thiazolidinones 5 and the corresponding 1-oxides, 6, 9 and 10 are described. The base used in these elimination reactions is potassium-1,2,4-triazole.

The rearrangement of 3-oxo-14β-hydroxy-12β-methanesulfoxy-card-20(22)-enolide and 14β-hydroxy-12β-methanesulfoxy-pregnane-3,20-dione during elimination of the sulfoxygroups was studied. By means of 2D-NMR analysis the structures were determined as 13,17-seco-12,17-cyclo-steroids.

For possible biological activity, the title compounds were prepared and allowed to condense with hydrazine hydrate, phenyl hydrazine, hydroxylamine HCl, urea and thiourea to give the pyrazolines 3, isoxazolines 4, oxo and thioxopyrimidines 5, respectively.

Diethyl-3-amino-2-cyano-2-pentendioate (1) reacts with aromatic amines and aminohetero-cyclic compounds to yield amide derivatives (2 c-h). The latter derivatives were utilised in synthesis of pyridazines (4a, b), pyrimidine (6), pyridone (9) and pyrano[4,3-b]pyridine (16a, b) derivatives via reaction with aryldiazonium chloride, trichloroacetonitrile, sodiummethoxide and cinnamonitrile derivatives, respectively.

From Hagenia abyssinica, 26 compounds were isolated, mostly phloracylophenones with one to three phloroglucinol units. The structure elucidation of three phloracylophenones with one phloroglucinol unit is described.

For the Koso constituents K6 and K8, we previously proposed the structures 1a, b and 2a, b [1]. These assignments have been confirmed by synthesis.

From the rootbark of Tabernaemontana chippii and the stembark of T. dichotoma a novel dimeric indole alkaloid was isolated which was named monogagaine. It was assigned structure 1 on the basis of spectral data. It showed antimicrobial activity against Bacillus subtilis.

4-Methylcyclo-art-22-ene-3,25-diol was isolated from Euphorbia lactae and its structure identified by elemental analysis, mass spectrometry and proton NMR spectroscopy.