Incorporations of [1-13C]?, [2-13C]?, [1,2-13C2]-acetates and [13C]-methionine into anditomin, a metabolite of , indicate its formation by a mixed polyketide-terpenoid biosynthetic pathway similar to that elucidated for andibenin; observations are made on the possible biosynthetic relationship of the metabolites with austin and terretonin, mycotoxins recently isolated from and respectively. 相似文献
The biosynthesis of the tetrahydroanthraquinone, altersolanol A (), by has been established by the incorporation of [1,2-13C2]-acetate. A blocked culture of was utilized to reveal that is metabolized to altersolanol B and macrosporin. 相似文献
Feeding experiments with [2-3H3]acetate and [2-13C2H3]acetate in Thom No. 14 indicated that the hydrogen at C-2 in terrecyclic acid A is incorporated without migration from the precursor acetic acid; the results favour our group's earlier speculation for the cyclization to the tricyclic skeleton in the biosynthetic scheme. 相似文献
Oxidation of the complexes -[M(CNR)2(dppe)2] (A) (M = Mo or W; R = Me, But or CH3C6H4-; dppe = Ph2PCH2CH2PPh2) with diiodine or silver (I) salts gives the paramagnetic cations -[M(CNR)2(dppe)2]+, (M = Mo, R = CH3C6H4-; M = W, R = But) and -[M(CNR)2(dppe)2]2+ (M = Mo, R = Me or CH3C6H4-; M = W, R = Me or But). Mixtures of products are generally produced when dichlorine or dibromine are the oxidising agents, however pure salts, the seven-coordinate complex cations [MX(CNC6H4CH3-)2(dppe)2]+ (B, X = Cl or Br) have been isolated. A simple molecular orbital scheme is proposed for complexes (A) and used to discuss their electronic spectra and their oxidation. 相似文献
The synthesis and mechanism of formation of phosphonium salts of the type [R3CFXY]Z? (where X = F, Cl, Br; Y = Br, Cl; Z = Br, Cl), -phosphonium salts of the type [R3CF2R3]2Br?, and phosphoranium salts of the type [R3FR3]X? (X = Br, Cl) will be presented. The applicability of these substrates in the generation of useful nucleophilic or electrophilic synthetic intermediates will be discussed. 相似文献
Trioxotrifluoroosmates(VIII) M[OsO3F3] (M = Cs, Rb, K) have been prepared by direct combination of OsO3F2 and the appropriate alkali fluoride MF. The reaction of OsO4 with M′F (M′ = Cs, Rb) in aqueous solution produces the tetraoxodifluoroosmates(VIII) M′2[OsO4F2]. On the basis of their vibrational spectra the assignment of a (C3v) structure to [OsO3F3]? and a (C2v) to [OsO4F2]2? is proposed. The electronic spectra of the anions have been recorded and are interpreted using the optical electronegativity concept. 相似文献
A practical synthesis of [Ph3CH2F]BF4? is reported two routes, fluorination of [Ph3CH2OH]BF4? with DAST or hydrolysis of the phosphoranium salt, [Ph3FPh3]Br?. 相似文献
The crystal structure of a bis(triphenylphosphine)iminium salt of the 1:1 adduct of [FeH(CO)4]? and dimethyl acetylenecarboxylate has been determined from three-dimensional X-ray data collected by the counter method. Single crystals belong to the triclinic space space group P, with two units of [C36H30NP2]+[C10H7FeO8]? in a cell of dimensions: = 13.918(2), = 15.669(5), = 9.909(2) Å, = 91.22(3), = 94.83(2), and = 77.62(2)°. The structure was refined to a conventional of 0.068 for 5373 observed reflections. The resulting structure indicates that the complex anion is η3-[-2,3-bis(methoxycarbonyl)acryloyl]tricarbonylferrate, the coordination around the iron atom being described as a considerably distorted trigonal bipyramid. A comparison of the present structure with the structures of related complexes suggests that the η3-acryloyl portion is best represented as an intermediate of (η3-allyl) with the oxygen atom and (η2-olefin + η1-acyl). The short Fe-C(acyl) length of 1.897(5) Å implies an enhanced back-donation of electrons from the iron atom to the acyl group. 相似文献
Studies of the 13C N.M.R. spectra of the series RhX[P(Ch2CH2CHCH2)3] and RhX[P(CH2CH2CH2CHCH2)3] where x Cl or Br have revealed that (a) the J(103Rh-13C) (olefin) for the complexes studied is only ? that found for square-planar complexes, and (b) the fluxional character in the olefinic carbons observed for the compounds RhX[P(CH2CH2CHCH2)3] is related to the partial rotation of the olefin about the rhodium-olefin bond. 相似文献
The 6-phenyl-dihydro-α-pyrone moiety of psilotin is formed from [2′,3′-13C2,1′-14C,-4-3H]phenylalanine in the plant with retention of all the isotopes. 相似文献
[24-2H]-, [25-2H]-, and [23,23,25-2H3]-24ξ-methylcholesterol as well as [23,23,25-2H3]-24-methylenecholesterol were metabolized in the silkworm to cholesterol containing zero, one, three and three deuterim, respectively. 相似文献
The synthesis of tetracyclo[5.4.1.04,12.09.12]dodecan-6-one via an intramolelecular photocycloaddition, its reduction to the hydrocarbon and its ring-contraction to tetracyclo-[4.4.1.03,11.09,11]undecane derivative is described. 相似文献
Pentacoordinated aminosulphur (IV) trifluorides, R2NF3, (in this paper the lone pair in S(IV)-derivatives is always considered as a ligand) and aminosulphur(VI)-oxidetrifluorides, R2NS(O)F3, readily lose a fluoride ion to Lewis acids (AsF5, SbF5, BF3) to give sulphur-containing cationic species [R2NF2]+ and [R2NS(O)F2]+ with tetracoordinated sulphur. Tetracoordinated neutral dialkylaminosulphur(IV)-oxidefluorides, R2N(O)F, and amino-imino sulphur(IV)fluorides, R2N(=NRf)F, give three-coordinated sulphur cations [R2NO]+] or [R2NNRf]+.The three-coordinated sulphur(VI)cation [R2NS(O)NR]+ has also been formed. 相似文献
The metal carbonyl anions [Fe(η-C5H5(CO)2]? and [Re(CO)5] undergo regio- and site-specific [2 + 2]-cycloadditions with the ketenimines Ph2CCNR (R = Me, Ph) to give the (isolable) anionic complexes [Ln(O)}]? (LnM = Fe(η-C5H5)CO, Re(CO)4) which have been alkylated and acylated at the exocyclic oxygen atom of the carbonyl function. The result is stable neutral complexes having a metallaazetidine structure which is composed of an α-metallated enamine and an N,O carbene part. IR, 1H, and 13C NMR data are presented. 相似文献
In boiling benzene, 1-phenyl-3,4-dimethylphosphole (L) with [(C5H5)Fe(CO)2]2 gives mainly a classical σ-complex in which L relaces one terminal CO. In boiling xylene, however, L also gives 3,4-dimethylphosphaferrocene and 2-phenyl-3,4-dimethylphosphaferrocene resulting from a P—Ph bond cleavage followed by a C-phenylation of the phospholyl nucleus in the second case. The same reaction with 1-phenylphosphole yields phosphaferrocene itself and a mixture of 2- and 3-phenylphosphaferrocene. The phosphaferrocenes thus prepared are exclusively acetylated at the phospholyl nucleus by the CH3CGClAlCl3 complex in CH2Cl2.With the unsubstituted phosphaferrocene, the acetylation takes place at the 2 and 3 positions (ratio ~ ) 1H, 13C, 13P NMR and mass spectral data are given. The phosphaferrocene system is characterized by a very large 1J(P—C) coupling (~60 Hz) and a very shielded phosphorus atom. 相似文献
In the 1H NMR spectrum of the complex [Os3H3(CO)9CH2]+ at 30°C, under conditions of rapid exchange, the single hydride resonance has two sets of satellites of equal intensity (separated by 32.0 and 28.8 Hz) caused by 187Os1H spin—spin coupling. The spectral data rule out the upright carbenium ion structure for the complex, and are consistent with the fluxional process involving hydrocarbon ligand rotation about the CH2 axis in a tilted structure, with concomitant rotation of the Os3H3(CO)9 moiety. 相似文献
A new series of perovskite-like compounds CMn7O12 have been synthesized under high pressure and high temperature conditions. C is a large divalent or trivalent cation such as Ca, Cd, Sr, La and Nd. The structures of the quenched materials have been determined from powder X-ray data. They are distortions of the NaMn7O12 cubic structure. The [C2+Mn3+3](Mn3+3Mn4+)O12 compounds are trigonal (). The C2+ and Mn3+ as well as the Mn3+ and Mn4+ cations are ordered on the corresponding A and B sites of the perovskite structure, respectively. The [C3+Mn3+3] (Mn3+4)O12 compounds are monoclinic (). In these compounds the order exists only in the A sites. It is shown that the lower symmetry may be the result of a cooperative Jahn-Teller effect of the Mn3+ cations occupying the B sites. 相似文献
The displacement of tetrahydrofuran (THF) from W(CO)5(THF) with hexaphenylcarbodiphosphorane yields a compound with a carbon-metal bond (CO)5W C[P(C6H5)3]2. The in situ photolysis of tungsten hexacarbonyl and hexaphenylcarbodiphosphorane, however, yields a product (CO)5W?CC +P(C6H5)3. Ethylenebis(triphenylphosphine)platinum and hexaphenylcarbodiphosphorane in benzene yield a platinum containing heterocycle [(C6H5)3P]2-(C6H5)3. 相似文献
Infrared spectra of new iron(III) complexes with urea derivatives: [Fe (CH3HNCONH2)6]X3; [Fe(C2H5HNCONH2)6]X3 and [Fe(CH3-HNCONHCH3)6]X3 (where X = Cl?, NO?3 or SO2?4) have been recorded and their interpretation given. The analysis of the infrared spectra was based on a comparison of the positions of bands corresponding to the vibrations of characteristic groups appearing in the complexes and the free ligands. Comparison and analysis of the data show that the urea derivatives coordinate with mono- and disubstituted iron(III) through the oxygen atom of the carbonyl group. 相似文献
Reaction of [PdCl2(PBut2Ph)]2 with silver acetate gives the internally metalated complex [PButPh]2(μ-Cl)2. This reacts with TlC5H5 and LiC5Me5 with chloride-bridge cleavage to yield C5R5PPButPh (R = H, Me). The complex [PBut2]2(μ-Cl)2,prepared from [PdCl2(PBut3)]2 and CH3COOAg, is analogously converted into C5R5But2. The chloride complex C5H5Pd(PBut5Ph)CI does not eliminate HCl to form C5H5PButPh. 相似文献