Volume 37, Issue 4

Butylantimony(III) bromides react with Mg in tetrahydrofuran (THF) even in presence of Me 3 SiCl exclusively with Sb-Sb-coupling: Starting from Bu 2 SbBr, Bu 2 SbSbBu 2 is formed and BuSbBr 2 is reduced to (BuSb) x . Sb-Si-coupling dominates in the reactions of Ph 2 SbBr or t-Bu 2 SbCl with Mg/Me 3 SiCl/THF yielding Ph 2 SbSiMe 3 or t-Bu 2 SbSiMe 3 . Both Sb-Sb- and Sb-Si-coupling reactions are observed, when PhSbBr 2 reacts with Mg and Me 3 SiCl yielding PhSb(SiMe 3 ) 2 and (PhSb) x . The same reactants can also form the distibanes Ph 2 (SiMe 3 ) 2 Sb 2 and Ph(SiMe 3 ) 3 Sb 2 . The reaction of t-BuSbCl 2 with Mg/Me 3 SiCl yields the stibines t-BuSb(SiMe 3 ) 2 and Sb(SiMe 3 ) 3 together with (t-BuSb) 4 . In the reactions of t-BuSbCl 2 or PhSbBr 2 the ratio of Sb-Sb- and Sb-Si-coupling can be strongly influenced by using different reaction conditions.

S,N-Bis(heptafluoroisopropyl)sulphurfluorideimide (1) is prepared by the reaction of i-C 3 F 7 SF 3 with (CF 3 ) 2 CNH in the presence of CsF. The reaction with AlCl 3 leads to two elimination products 4 and 5. With XeF 2 the sulphur(II) atom in 4 and 5 is oxidized. In 1 the sulphur-bonded fluorine can be substituted by -OCH 3 to give i-C 3 F 7 NS(i-C 3 F 7 )OCH 3 (7).

1-Diphenylphosphinopropan-2-on-hydrobromide (1a), 2-Diphenylphosphino-1-phenylethan- 1-on-hydrobromide (2a), and 1,3-Bis(diphenylphosphino)propan-2-on-bis(hydrobromide) (3a) were prepared by the reaction of the corresponding β-bromo-ketones with diphenyl(trimethylsilyl)phosphine. By treatment with NaOH the hydrobromides 1a-3a were converted into the ketones 1b-3b. The reactions of 1a-3a with (R)-(+)-1-phenylethylamine were investigated.

The highly reactive chloroacyl(diphenyl)phosphane oxides RC(O)-P(O)Ph 2 (2a-d, g) [R = HCCl 2 (a), CCl 3 (b), CH 3 CHCl (c), CH 3 CCl 2 (d), ClCH 2 CH 2 (e), CH 3 CHClCH 2 (f), ClCH 2 (CH 2 ) 2 (g)] are obtained by oxidation of the thermally labile chloroacyl(diphenyl)- phosphanes RC(O)-PPh 2 (1a-d, g) with molecular oxygen in ether at low temperatures. While hydrolysis leads to a complete decomposition of 2a-d, g, the oxidation of 1a, c, e-g with oxygen in the presence of HP(O)Ph 2 yields the diphosphorylated alcohols RC[P(O)Ph 2 ] 2 OH (3a, c, e-g). 3e, f can be interpreted as trapping products of the not isolable oxides 2e, f. In tetrachloroethene a partial transformation of 3a into the phosphinate RC[P(O)Ph 2 ][OP(O)Ph 2 ]H can be observed which can be followed 31 P{ 1 H}-NMR spectroscopically. In solution the alcohols 3c, e-g decompose to give HP(O)Ph 2 and the corresponding phosphane oxides 2c, e-g.

11 B and 13 C NMR data of peralkylated nido-2,3,4,5-tetracarbahexaboranes(6) are reported. Application of selective heteronuclear triple resonance experiments 13 C{ 1 H, 11 B} enables to assign the structures of various isomers. The magnitude of the coupling constants 1 J( 11 B 11 B), 1 J( 13 C 11 B) and 1 J( 13 C 13 C) is in accord with expectations based on the conception of bonding in carboranes. The comparison of δ 11 B and δ 13 C data of the nido- 2,3,4,5-tetracarboranes(6) with δ 13 C-data of corresponding non-classical carbocations shows the influence of charge upon the nuclear shielding of carbon in the latter.

Investigations in the system Ca-Cu-As resulted in the discovery of CaCu 4 As 2 . The phase crystallizes in a rhombohedral structure (Trigonal axes: a = 417.3(6) pm, c = 2262(3) pm, space group R3̅m). The conductivity varies from 47 to 89 (Ωcm) -1 having a minimum at 250 K.

KOH reacts with bis(isopropyl-trimethylsilyl)-amino-difluorosilane to give the fluoro-silanol 1. An aminofluorosiloxane 2 is obtained in the reaction of [(Me 3 Si) 2 N] 2 SiF 2 with KOH via a 1,3-silyl-group migration. The four-membered SiOSiN ring 5 can be prepared in several steps from 1. Six-membered SiO rings 8-10 are formed in the reaction of 1,3-fluorosilanols 6 and 7 with butyllithium. Lithiated 2 reacts with PCl 3 to give a four-membered P 2 N 2 ring 11, and with 2-methyl-2-propenal to give two isomeric (2 + 4) cycloadducts 12 and 13. The silicenium ylid formed initially by thermal elimation of LiF from lithiated 2 in PE/THF cross-dimerises to give a Si 2 N 2 ring 14. If the reaction is carried out in n-heptane, the product after recrystallisation from acetone, 16, is an isomer of 14. The crystal structures of 14 and 16 have been determined.

Silylated diamines and diimines of type 13, 14 and 9-11 react with sulfur chlorine compounds SCl 2 , SOCl 2 , 8 and 12 to give 1-7 as linear S-N polymers with p-phenylen groups. Subsequent doping with acceptors (I 2 , Br 2 , AsF 5 ) increases conductivity of 1-5 to ca. 10 -4 Ω -1 cm -1 .

Phenazine free E 2 P-TCNQ, C 28 H 22 N 6 , M r = 442.53 is monoclinic, P2 1 /c, a = 10.875(3), b = 14.679(4), c = 14.526(2) Å, β = 90.90(2)°, V = 2321.9 Å 3 , Z = 4, d c = 1.27 Mgm -3 , the compound doped with 50% phenazine, E 2 P-P-(TCNQ) 2 C 52 H 34 N 12 , M r = 826.93, is triclinic, P1̅, a = 7.739(3), b = 15.899(6), c = 17.037(7) Å, α = 83.44(3), β = 88.34(3), γ = 83.19(3)°, V = 2067.7 Å, Z = 2, d c = 1.33 Mgm -3 . E 2 P-TCNQ was refined to R = 0.066 for 1880 reflections. It consists of planar TCNQ anions and bent E 2 P cations (dihedral angle 17.7° along the line N-N) arranged in regular mixed stacks along c. The structure of E 2 P-P-(TCNQ) 2 could be solved principally, but did not refine well (R = 0.165 for 1206 reflections). Regular segregated stacks of the phenazine and the TCNQ moieties are formed, and along the cationic stack the E 2 P + cations and the neutral phenazine molecules alternate.

In the course of systematic studies on sila-substituted drugs the nifedipine-like 1.4-dihydropyridine derivatives 4a, 4b and 4c were prepared and investigated with respect to sila-substitution effects. By X-ray diffraction analyses 4a, 4b and 4c were found to be isostructural. The C/Si-analogues exhibit similar spasmolytic activities (in vitro, guinea pig ileum), comparable with that of nifedipine. However, the compounds differ substantially in their in vivo activity, as measured by the antihypertensive effect on the renal-hypertensive rat. The experimental results are discussed with respect to the carbon/silicon exchange.

The four stereoisomers of the grass herbicide Metolachlor, the isomerism of which is based on a combination of a chiral centre and a chiral axis, were prepared, and their absolute configurations determined by X-ray analysis. The synthesis was achieved by using optically active starting materials and new optically active carbamates as intermediates. The herbicidal activity is mainly influenced by the chiral centre, the S-isomers being the most active ones.

Enneacarbonyldiiron reacts with 3,3,4,4-tetramethyl-1,2-diazetine (L) or its mono-N-oxide (L′) to form complexes (L)Fe(CO) 4 (3), (L)Fe 2 (CO) 7 (4), (L)Fe 2 (CO) 6 (5), or (L′)Fe(CO) 4 (6), and small amounts of deoxygenated 4 and 5, respectively. Formation and stability of the complexes is compared with those of ligands with smaller and larger ring sizes and discussed in terms of the electronic properties of the ligand lone-pair Orbitals. The molecular structure of 4 is established by X-ray analysis.

Chromium and tungsten carbonyls react with 3,3,4,4-tetramethyl-1,2-diazetine (1) or its mono-N-oxide (2) to form complexes (1)M(CO) 5 , (1) 2 M(CO) 4 , (1)M 2 (CO) 10 , (1) 2 M 2 (CO) 8 , (1) 3 M 2 (CO) 6 or (2)M(CO) 5 and (2) 2 M(CO) 4 , resp. In the reactions of 2 some deoxygenation affords complexes of 1 as by-products. The stability of these and other complexes of the N=N group is related to the ring size of the cyclic diazene ligand.

2,2,2-Trimethoxy-3,3-bis(trifluoromethyl)-2,2-dihydro-1,4,2-oxazaphosphol-4-enes on thermolysis undergo a 1,3-dipolar cycloreversion reaction with formation of bis(trifluoromethyl) substituted nitrile ylides and trimethyl phosphate. The nitrile ylides are trapped by N-sulfinyl aniline, phenyl isocyanate, phenyl isothiocyanate, diphenyl ketene, and carbon disulfide. Site selectivity and regiochemistry of the [3 + 2]cycloaddition reactions are described. The results are compared with those obtained from [3 + 2]cycloaddition reactions of nitrile imines, nitrile oxides, alkyl, and aryl substituted nitrile ylides with heterocumulenes.

The compounds 2-7 were isolated from solutions of phenanthrene (1) and nitrogendi-oxide in carbon tetrachloride after irradiation with UV light having long wavelengths (λ > 290 nm). With the help of spectroscopical methods the proposed structures are derived. Radical mechanisms are proposed for these reactions.

Enamines from acetaldehyde, propionaldehyde and cyclohexanone produce coloured complexes with disodium-pentakis-(cyano-C)-nitrosylferrate(2) more rapidly than the carbonyl components together with piperidine, so indicating enamine intermediates. - The Legal complexes from acetaldehyde and acetone are protonated to the corresponding Simon-Awe complexes.

The indolenine alkaloids raucaffricine and perakine were isolated from Rauwolfia caffra Sonder and their PFT 13 C{ 1 H}-NMR spectra studied for the first time. The interpretations of their spectra were accomplished in correlating with those of quinuclidine, indole, methyl-α-D-galactopyranoside, methyl-β-D-galactopyranoside, methyl-2,6-di-O-methyl-α-D-galactopyranoside and methyl-3-O-methyl-β-D-galactopyranoside.

Numerous 1-substituted 4,4,4-trichloro-Δ 2 -butenes are prepared from the 1-substituted 2-bromo-4,4,4-trichloro-butanes by HBr-elimination and by substitution reactions.

Two new flavonol glycosides, herbacetin-and gossypetin-3-β-D-(2-O-β-D-glucopyrano-sidoglucopyranoside)-8-β-D -glucopyranoside have been isolated from the aerial parts of Equisetum hyemale L. together with the known kaempferol-3-β-D-(2-O-β-D-glucopyrano-sidoglucopyranoside) -7-β-D -glucopyranoside.

The relative configuration of the thermolabile chamazulene precursor matricine has been established by NMR spectrometric studies. The NMR spectral data prove to be consistent with the well-known structure of the chamomile component. On the basis of our results the levorotatory natural substance moreover can be specified stereochemically as (−)-(3S*, 3aR*, 4S*, 9R*, 9aS*, 9bS*)-4-acetoxy-2,3,3a,4,5,9,9a,9b-octahydro-9-hydroxy-3,6,9-trimethylazuleno[4,5-b]furan-2-one.

Extensions of von Braun Cyanogen bromide reaction on Ephedra alkaloids and simpler bases have resulted in synthesis of substituted oxazolidines and a whole series of nitrogen analogues of ephedrine, desoxy ephedrine and simpler amines. The general applicability and limitations of such extension of the reaction are also discussed.

Two new furanoid diterpenes of clerodane type, 6β-hydroxyteuscordin (1) and 2β, 6β-dihydroxyteuscordin (3) have been isolated from Teucrium scordium var. scordium, Lamiaceae. Their structures and stereochemistry have been determined on the basis of chemical reactions and spectroscopic evidence.

A new coumarin, named trigocoumarin has been isolated from Trigonella foenumgraecum along with some known compounds. Based upon its spectral (IR, UV, NMR and MS) and analytical data, trigocoumarin has been assigned the structure: 3-(ethoxycarbonyl)-methyl-4-methyl-5,8-dimethoxycoumarin.

New methods are reported which allow the synthesis of pure UCl 5 and UCl 6 in high yields. UCl 5 is obtained by chlorination of UF 5 · 2 SbF 5 with BCl 3 at low temperatures, UCl 6 by direct chlorination of UCl 4 in SbCl 5 .