Volume 42, Issue 9

N-Trimethylsilyl-benzophenoneimine Ph 2 C=NSiMe 3 is able to “store" the silaethene Me 2 Si = C(SiMe 3 ) 2 (1). produced from Me 2 SiF-CLi(SiMe 3 ) 2 , under formation of a [2+4]- and [2+2]-cycloadduct (2, 3), respectively. Above 60 °C (above 120 °C) 2 or 3 by the way of 1 transform into a 1:5 mixture of 2 and 3 (into a 1:1 mixture of the dimer of 1 and the insertion product of 1 into the SiN-bond of Ph 2 C=NSiMe 3 ). In the presence of 2,3-dimethyl-1.3-butadiene (dmb), 2 or 3 form by way of the reaction of the intermediate 1 with dmb a [2 + 4]-cycloadduct (75%) and an ene reaction product (25%). The rate constants of the first order decomposition of 2 or 3 in the presence of dmb (80 °C. solvents like Et 2O, Q 6 H 6 are in the order of 2x10 -4 s -1 (τ 1/2 ca. 1 h) and 3x10 - 5 s -1 (τ 1/2 ca. 6 h). respectively.

Silaethene Me 2 Si = C(SiMe 3 ) 2 (1), stored as Ph 2 C=NSiMe 3 adducts and regenerated from the adducts at about 100 °C as a reaction intermediate, combines with reactants a-b (e. g. HO-H, RO-H. RCOO-H, RS-H. RHN-H, Ph 2 CN-H, RO-SiR 3 , R 2 N-SiR 3 , Ph 2 CN-SiR 3 , Cl-GeR 3 , Cl-SnR 3 ) with insertion into the a-b bond, with a=b (e.g. 0 = CPh 2 , Me 3 SiN = CPh 2 , CH 2 =CHOMe, cis-piperylene), a=b=c (e.g. RN = N = N, O = N=N). a=b-c=d (e.g. butadiene, isoprene, trans-piperylene, 2,3-dimethylbutadiene, cyclopentadiene, anthracene, benzophenone, N-trimethylsilylbenzophenoneimine) under [2+2]-, [2+3]- as well as [2+A]-cycloaddition and with a=b-c-H (e.g. propene, butenes, isoprene. 2.3-dimethylbutadiene, acetone) under ene reac­tion. According to relative reaction rates, insertion and [2+2]-cycloadditions seem to proceed in two reaction steps, whereas [2+4]-cycloadditions and ene reactions with organic dienes and enes obviously are one step reactions. For relative reactivities cf. Table I.

1,2-Di-tert-butyldiphosphane monoxide (2) and 1,2-di-tert-butyldiphosphane dioxide (3) have been prepared by reacting 1,2-di-tert-butyldiphosphane (1) with cum ene hydroperoxide and pure oxygen, respectively. Both compounds are formed as red trans-oriented tert-butyl substituents.

The new compound [Ba(en) 4 ] 2 As 4 Te 6 has been prepared by reaction of appropriate mixtures of the elements in dry ethylenediamine. It crystallizes in the monoclinic system, space group P2 1 /n with a = 1776.0(6) pm, b = 1459.9(6) pm, c = 1000.0(4) pm, β = 101.8(1)°. The As 4 Te 6 4- anion forms a six-membered ring As 4 Te 2 of chair conformation, in which two As-As groups are bridged by Te atom s. A t each As atom a further exocyclic Te neighbour is bonded in the equatorial position. The Ba 2+ cation is eight-coordinated by the bidentate ethylenediamine ligand.

(PhP) 5 and lithium dialkylamides in tetrahydrofuran form equilibrium mixtures of lithium aminophenylphosphides (PhP) n NR - with n = 3 and (mainly) 2. The monophosphides (n = 1) are not formed; it is concluded that they are generally unstable, decomposing to aminodiphosphides and cyclophosphines. Alkylation of an equilibrium mixture gives 1-alkyl-2-dialkylamino-diphenyl- diphosphines which, however, are thermally unstable. (PhP) 5 degradation equilibria using differ­ent anionic nucleophiles are compared.

Preparative methods have been explored for the synthesis of small, volatile polysilaalkanes, which could serve as starting materials for the production of amorphous silicon a-SiC:H. High yield pathways have been developed for H 3 SiCH 2 CH 2 SiH 3 and H 3 SiCH 2 CH 2 CH 2 SiH 3 . These compounds can be converted into symmetrically halogen-functional derivatives through the reac­tions with SnCl 4 or Br 2 . The homologous H 3 SiCH 2 CH 2 SiH 2 CH 3 has also been prepared and halogenated, starting from the corresponding vinylsilane via the hydrosilylation route. Allylsilanes were the source of the synthesis of H 3 SiCH 2 CH=CH 2 , CH 3 SiH 2 CH 2 CH=CH, SiH 2 (CH 2 CH = CH 2 ) 2 , SiH 2 (CH 2 CH 2 CH 2 SiH 3 ) 2 , or HSi(CH 2 CH 2 CH 2 SiH 3 ) 3 . Methylated deriva­tives are also available. - Some physical and spectroscopic properties of the new compounds have been investigated. In particular. NMR data were collected and used for an assessment of structure and isomerism.

The title compound has been prepared from (PPh 4 ) 2 [Mo 2 (O 2 C-Ph) 4 Cl 2 ] and CCl 4 in CH 2 Cl 2 solution as moisture sensitive crystals, which are black in reflexion and yellow in transmission. (PPh 4 ) 2 [Mo 2 (O 2 C-Ph) 4 Cl 4 ] · 2 CH 2 Cl 2 was characterized by a X-ray crystal structure determination (7873 observed independent reflexions. R = 0.048). It crystallizes in the space group P1̄ with one formula unit in the unit cell; the lattice constants are a = 1186.4; b = 1404.0; c = 1451.0 pm; α = 61.98°; β = 78.91°; γ = 78.26°. The structure consists of PPh 4 ⊕ ions. CH 2 Cl 2 molecules and centrosymmetric anions [Mo 2 (O 2 C-Ph) 4 Cl 4 ] 2⊝ containinga molybdenum d 3 d 3 unit with a relatively long Mo=Mo bond of 249.6 pm. The Mo≡Mo group is spanned in a chelate manner by four O atoms of two benzoate groups and by two further single O atoms of two further benzoate groups. Two terminal Cl atoms on each Mo atom complete the pentagonal bipyramidal coordination spheres about the Mo atoms.

Single crystals of dark blue MnF 4 have been obtained by high pressure fluorination (p F2 = 3 kbar) of MnF 2 . There exist two modifications: α-MnF 4 crystallizes tetragonally body centered with a = 12.63(1), c = 6.049(5) Å, space group I4 1 /a-C 4h 6 (No. 88). Z = 16; the structure of β-MnF 4, (probably) rhombohedral with a = 19.56(2). c = 13.00(1) Å, Z = 72, is yet unknown in detail. MnF 4 is paramagnetic with ,μ eff (301.2 K) = 3.87 B. M. . The Curie-Weiss law is obeyed down to 22.4 K; the Madelung Part of lattice energy (MAPLE) is calculated to be 2475 kcal/mol.

(PhAsNSN)2 (1) reacts with M(CO) 4 (C 7 H 8 ) (M = a Cr. b Mo) to yield (PhAsNSN) 2 M(CO) 4 (2). 2a and 2b are dark red air stable complexes. 2b was characterized by X-ray diffraction. Crystals of 2b are monoclinic, space group C2/c, with a = 2884.7(4). b = 1166.2(2), c = 1344.1(2) pm, fβ = 104.81(2)° and Z = 8. The molecule exhibits approximate mm (C 2v ) symmetry with mean bond lengths: Mo-As 255.1. Mo-C 201.8. As-N 186.2 and S -N 152.8 pm.

Reaction of 2-BrC 6 H 4 PCl 2 (1) with methyl lithium gave 2-BrC 6 H 4 PMe ; (2). Metalation of 2 with n-butyl lithium and further reaction of the lithio-derivative 2-LiC 6 H 4 PMe 2 with triphenyl phos­phite yielded the title compound. P(C 6 H 4 PMe 2 -2) 3 (3). characterized by NMR and mass spectro­scopy as well as by an X-ray structure analysis. Quaternization of 2 with methyl iodide gave [2-BrC 6 H 4 PMe 3 ]I (2a). the molecular structure of which has also been determined by single­crystal diffraction methods.

The photochemical reaction of o-C 6 H 4 (PR 2 ) 2 ; R = OCH 3, OC 2 H 5 , m-C 6 H 4 (PR 2 ) 2 ; R = N(CH 3 ) : and p-C 6 H 4 (PR 2 ) 2 ; R = OCH 3 . N(CH 3 ) 2 with (tricarbonylj(methylcyclopentadienyl)- manganese (Cp')Mn(CO) 3 (6) and p-C 6 H 4 (P(N(CHO 3 ) 2 ) 2 ) 2 with (tricarbonyl)(methyl)(cyclopenta- dienyl)molybdenum (CH 3 )(Cp)Mo(CO) 3 (7) yields new manganese and molybdenum complexes. o-Phenylen-bis(phosphonousaciddimethylester)(carbonyl)(methylcyclopentadienyl )manganese (8) forms yellow crystals, whose structure is reported. The reaction of o-C 6 H 4 (P(OCH 3 ) 2 ) 2 (1) with NiCl 2 gives a 1:1 phosphane complex (14). Ni(OH)Clopm. The complexes are characterized by elemental analysis, 1 H NMR, 31 P NMR, IR and mass spectroscopy.

NiCl2 reacts with NaSR in methanol solution to give the black diamagnetic complexes [Ni5(SR) 10 ] (R = Et, 1) and [Ni4(SR) 8 ] (R = C 6 H 11 , 2). Crystals of 1 are monoclinic, space group P2 1 /h with a = 13.149(4), b = 15.571(4), c = 17.917(5) Å , β = 105.31(2)° and Z = 4. 2 crystallizes from methylene chloride with sixteen solvent molecules per unit cell in the orthorhombic space group Ibca with a = 17.902(8), b = 18.289(8), c = 37.99(2) Å and Z = 8. The structures of 1 and [Ni 4 (SC 6 HM) 8 ] · 2 CH 2 Cl 2 (3) have been determined by X-ray crystallography and refined to R(R W ) = 0.072 (0.062) and 0.119 (0.128), respectively. Both complexes are cyclic neutral molecules and contain square planar NiS 4 coordination sites (1: mean Ni - S 2.200 Å , mean S -Ni -S 81.8 ( 2 x ) . 98.3 ( 2 x ) , 170.8° ( 2 x ) ; 2: mean Ni - S 2.213 Å , mean S - Ni - S 80.9 (2 x ) , 98.2 ( 2 x ) , 167.5°(2 x )) condensed via opposite edges. A s a result, prismatic sulfur frameworks are observed which are pentagonal in the case of 1 and tetragonal in the case of 2. Their lateral faces are centered by Ni atoms. The symmetry of the Ni-S core portion approaches D 5h for 1 and D 4h for 2. With reference to the toroidal N i-S frameworks, the sulfur-carbon bonds of each pair of opposite ligands are in axial and equatorial positions, respectively. This configuration alternates around the prismatic sulfur arrangement which is completely compatible with the even number of nickel atoms present in 2, but results in a node for 1 due to the five-fold symmetry.

A synthesis for a new 1,2,6-donor-acceptor-substituted chromophoric benzene system is given. This chromophore is incorporated in a bicyclo[2.2.2]octane system to build up model compounds for electro-optical and dielectrical studies. Furthermore a preparative convenient route to derivatives of 1,4-bis(diphenyl)bicyclo[2.2.2]octane is worked out. The structures of the new compounds are proven by spectroscopical means.

Visible, 1 H NMR and infrared spectra of the charge-transfer (CT) complexes of polynuclear- [2.2]paracyclophanes and their sulfur analogues as electron donors with 2,3-dichloro-5.6-dicyanobenzoquinone (DDQ ), tetracyanoethylene (TCNE) and 9-dicyanom ethylene-2,4,7-trinitrofluorene (DTF) as π-acceptors have been measured. The data indicate an unexpected high basicity of the polynuclear hydrocarbons relative to their sulfur analogues. The types of CT interactions as well as different factors governing the stability of the CT complexes studied are discussed. The effect of temperature on the CT complexes studied are discussed. The effect of temperature on the CT complexes with TCNE is reported.

Charge-transfer (CT) complexation between some [2.2]- and [2.2.2]paracyclophane-carbamates as donors with 2,3-dichloro-5.6-dicyanobenzoquinone (DDO ) as well as tetracyanoethylene (TCNE) as π-acceptors has been evidenced by VIS. 1 H NMR and IR spectroscopy. The site of interaction in the two different donor systems was determined. The results reveal no contribution of the nitrogen lone pair electrons of the carbamate functional group in the CT complexation. and the interaction is mainly of π-π* type. In addition, the existence of the transannular electronic interactions in [2.2]paracyclophane derivatives is responsible for CT complex formation.

The photoreactivity of 1,3-dihydro-2H̠ -benzimidazole-2-thione ( 1a ) and 2(3H )-benzothiazolethione ( 1b ) has been studied in several solvents in the presence of oxygen with or without methylene blue as a sensitizer. The corresponding disulfides (5a, b), 2-oxo derivatives (2 a , b), benzimidazole and benzothiazole (11a, b), and elem ental sulfur have been characterized as the main products. The UV irradiation of the disulfides 5a , b results in the formation of the same product pattern as the thiones 1 a , b. Photolysis of 2-chlorobenzothiazole (12) in acetonitrile gives a mixture of 2 b , 2,2'-dibenzothiazole (13). while photolysis of 12 in ethanol yields 2b and 11 b . Products and mechanisms are discussed and compared with previous studies in this area.

Quaternary salts of the amides of N-(3-quinolinecarbonyl) amino acids (7) cyclise under the influence of base to give fourteen membered rings (9). This dimerisation is a reaction with high diastereoselectivity. The addition product 9 can be regarded as lipophilic, masked NAD model compound: 9 oxidizes 2-propanol under ZnCl 2 catalysis to give in high yield acetone and the 1.4-dihydroquinoline.

Quaternary salts of the amides of N-(3-quinolinecarbonyl)-N-alkyl-amino acids (6) cyclise under the influence of base to the title compounds (7). This intramolecular addition is a reaction with high diastereoselectivity, dependent on the amino acid part. 7 disproportionates to 8 and 9. 7 behaves as lipophilic NAD model compound in the reaction with 2-propanol under ZnCl 2 catalysis.

The alkylation of morpholine enam ines of 2-oxo-cycloalkane-1-carbothionic acid anilides (1-3) with 1,2-dibromoethane under phase-transfer catalytic conditions yields enam ines of 1-oxo-2-(3-phenyl-tetrahydrothiazol-2-ylidene)-cycloalkanes (4-6). Compounds 4-6 were hydrolysed to appropriate keto derivatives 8-10. The structure of obtained com pounds was established on the basis of IR. NM R and MS spectral data.

1,5-Naphthalinediol yields with a secondary amine and formaldehyde under special conditions the mono Mannich base. Following hydrogenolysis with palladium charcoal results in 2-methyl- 1,5-naphthalinediol.

A high performance liquid chromatographic method was developed to study the pharmacokinetics of nicergoline and its two main m etabolites in humans. The analytes are extracted from blood, plasma and urine into a mixture of chloroform and ether, which is optimised in terms of recovery and absence of interferences. The analytes are separated on a small bore column filled with octadecylsilica. the mobile phase was a ternary mixture of water, acetonitrile and tetrahydrofurane with diisopropylamine for pH adjustment. To maintain the chromatographic stability. the mobile phase is circulated and a saturator column inserted between pump and sampler. Nicergoline is very unstable in blood, it could not be determined in human body fluids after a single dose of 10 mg nicergoline. Metabolite 1 reaches plasma concentrations of about 2 ng/ml after 40 min. metabolite 2 gains to about 8 ng/ml after 4 h. 67% of the dosed nicergoline are excreted in urine as free metabolite 2. free metabolite 1 occurred only in trace concentrations. 18.5% of the dosed drug were excreted as conjugated metabolite 2. 1.1% as conjugated metabolite 1.

The lipopentapeptide S-[2,3-bis(palmitoyloxy)-[2-R,S]-propyl]-N-palmitoyl-[R]-cysteinyl-[ R|- α-methylseryI-[R]-α-methylseryl-[S]-asparaginyl-[S]-alanine (Pam 3 Cys-α-MeSer-α-MeSer-Asn -Ala) has been synthesized as an analogue of the immunoadjuv- ant Pam 3 Cys-Ser-Ser-Asn -Ala (TPP) via fragment condensations. The two [R]-α-methylserine residues were introduced instead of [L]-serine in order to obtain a mitogenic lipopeptide resistant against proteases. As the parent lipopeptide TPP the analytically pure analogue with McSer was found to induce enhanced cell proliferation of spleen lymphocytes.

The reaction of 2-mercaptocarboxylic acids (3 B ) or methyl thioglycolates (3 A ) with 1.1'-carbonyldiimidazole and alkoxyamines produces 3-alkoxythiazolidin-2,4-diones (5). Acid catalyzed methanolysis of the tetrahydropyranyloxy group affords the cyclic N-hydroxy imides (6) which can easily be acylated with 3-chlorophenylisocyanate or dimethylcarbamoyl chloride to give compounds of type 7 or 8.

(NBu 4 ) 2 [Co 4 (SPh) 6 Cl 4 ] (1) and [Co 4 (SPh) 6 CU(PPh 3 ) 2 ] (2) are prepared by the reaction of (NBu 4 )[CoCl 3 (PPh 3 )] and [CoCl 2 (PPh 3 ) 2 ] with PhSSiMe 3 in toluene solution. The overall description of the Co 4 S 6 Cl 4 core is that o f a nearly regular Co 4 -tetrahedron inscribed in an irregular octahedron of the bridging S atoms resulting in an “adamantane” type cage. 1 reacts with Na[Mn(CO) 5 ] to form the dinuclear complex (NBu 4 )[Mn 2 (SPh) 3 (CO) 6 ] (4). Each Mn atom is bound to three CO and three μ 2 -SPh ligands. The Mn-Mn contact (318.5 pm) does not indicate metal-metal bonding.