Biosynthesis of highly modified meroterpenoids in aspergillus variecolor. Incorporation of 13C-labelled acetates and methionine into anditomin and andilesin C

Incorporations of [1-¹³C]?, [2-¹³C]?, [1,2-¹³C₂]-acetates and [¹³C]-methionine into anditomin, a metabolite of $\text{Aspergillus variecolor}$, 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 $\text{A. variecolor}$ metabolites with austin and terretonin, mycotoxins recently isolated from $\text{A. ustus}$ and $\text{A. terreus}$ respectively.     

Metabolites of Alternaria solani part V. Biosynthesis of altersolanol A and incorporation of altersolanol A-13Cx into altersolanol B and macrosporin

The biosynthesis of the tetrahydroanthraquinone, altersolanol A ($\text{1}$), by $\text{Alternaria solani}$ has been established by the incorporation of [1,2-¹³C₂]-acetate. A blocked culture of $\text{A. solani}$ was utilized to reveal that $\text{1}$ is metabolized to altersolanol B and macrosporin.     

Studies on the biosynthesis of terrecyclic acid A II confirmation of the cyclization mechanism and hydrogen shifts using [2-2H3]acetate and [213C2H3]acetate

Feeding experiments with [2-³H₃]acetate and [2-¹³C²H₃]acetate in $\text{Aspergillus terreus}$ 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.     

The chemical oxidation and electronic spectra of the complexes trans-[M(CNR)2(Ph2PCH2CH2PPh2)2] (M = Mo or W)

Oxidation of the complexes $\text{trans}$-[M(CNR)₂(dppe)₂] (A) (M = Mo or W; R = Me, Bu^t or CH₃C₆H₄-$\text{4}$; dppe = Ph₂PCH₂CH₂PPh₂) with diiodine or silver (I) salts gives the paramagnetic cations $\text{trans}$-[M(CNR)₂(dppe)₂]⁺, (M = Mo, R = CH₃C₆H₄-$\text{4}$; M = W, R = Bu^t) and $\text{trans}$-[M(CNR)₂(dppe)₂]²⁺ (M = Mo, R = Me or CH₃C₆H₄-$\text{4}$; M = W, R = Me or Bu^t). Mixtures of products are generally produced when dichlorine or dibromine are the oxidising agents, however pure salts, the seven-coordinate complex cations [MX(CNC₆H₄CH₃-$\text{4}$)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.     

Preparation and synthetic utility of fluorinated phosphonium salts,bisphosphonium salts and phosphoranium salts

The synthesis and mechanism of formation of phosphonium salts of the type [R₃$\text{P}\text{+}$CFXY]Z^? (where X = F, Cl, Br; Y = Br, Cl; Z = Br, Cl), $\text{bis}$-phosphonium salts of the type [R₃$\text{P}\text{+}$CF₂$\text{P}\text{+}$R₃]2Br^?, and phosphoranium salts of the type [R₃$\text{P}\text{+}$$\text{C}\text{?}$F$\text{P}\text{+}$R₃]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.     

Coordination chemistry of higher oxidation states. 10 [1]. Oxofluoroanions of osmium(VIII) [OsO4F2]2− and [OsO3F3]−

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 $\text{fac}$ (C_3v) structure to [OsO₃F₃]^? and a $\text{cis}$ (C_2v) to [OsO₄F₂]^2? is proposed. The electronic spectra of the anions have been recorded and are interpreted using the optical electronegativity concept.     

A practical synthesis of fluoromethyltriphenylphosphonium salts

A practical synthesis of [Ph₃$\text{P}\text{+}$CH₂F]BF₄^? is reported $\text{via}$ two routes, $\text{via}$ fluorination of [Ph₃$\text{P}\text{+}$CH₂OH]BF₄^? with DAST or $\text{via}$ hydrolysis of the phosphoranium salt, [Ph₃$\text{P}\text{+}$$\text{C}$F$\text{P}\text{+}$Ph₃]Br^?.     

X-ray molecular structure of the 1:1 adduct of [FeH(CO)4]− and dimethyl acetylenedicarboxylate. η3-[trans-2,3-bis(methoxycarbonyl)acryloyl]tricarbonylferrate

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$\text{1}$, with two units of [C₃₆H₃₀NP₂]⁺[C₁₀H₇FeO₈]^? in a cell of dimensions: $\text{a}$ = 13.918(2), $\text{b}$ = 15.669(5), $\text{c}$ = 9.909(2) Å, $\text{α}$ = 91.22(3), $\text{β}$ = 94.83(2), and $\text{γ}$ = 77.62(2)°. The structure was refined to a conventional $\text{R}$ of 0.068 for 5373 observed

reflections. The resulting structure indicates that the complex anion is η³-[$\text{trans}$-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.     

Carbon-13-nuclear magnetic resonance spectra of 5-coordinate tris-olefin complexes of rhodium(I)

Studies of the ¹³C N.M.R. spectra of the series RhX[P(Ch₂CH₂CHCH₂)₃] and RhX[P(CH₂CH₂CH₂CHCH₂)₃] where x  Cl or Br have revealed that (a) the J(¹⁰³Rh-¹³C) (olefin) for the complexes studied is only $\text{1}\text{2}$ ? $\text{1}\text{3}$ that found for square-planar complexes, and (b) the fluxional character in the olefinic carbons observed for the compounds RhX[P(CH₂CH₂CHCH₂)₃] is related to the partial rotation of the olefin about the rhodium-olefin bond.     

Biosynthesis of psilotin from [2′,3′-13C2,1′-14C,4-3H]phenylalanine studied with 13C-NMR

The 6-phenyl-dihydro-α-pyrone moiety of psilotin is formed from [2′,3′-¹³C₂,1′-¹⁴C,-4-³H]phenylalanine in the plant $\text{Psilotum}$$\text{nudum}$ with retention of all the isotopes.     

Mechanism of campesterol demethylation in insect

[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 $\text{Bombyx}$$\text{mori}$ to cholesterol containing zero, one, three and three deuterim, respectively.     

Synthesis of (4.5.5.5]fenestrane and a [4.4.5.5]fenestrane derivative

The synthesis of tetracyclo[5.4.1.0^4,12.0^9.12]dodecan-6-one $\text{12}$ via an intramolelecular photocycloaddition, its reduction to the hydrocarbon $\text{13}$ and its ring-contraction to tetracyclo-[4.4.1.0^3,11.0^9,11]undecane derivative $\text{16}$ is described.     

Amino-sulphur-fluorine derivatives as fluoride ion donors: preparation of three- and four-coordinated cations of sulphur (IV) and (VI) [1,2]

Pentacoordinated aminosulphur (IV) trifluorides, R₂N$\text{S}$F₃, (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 [R₂N$\text{S}$F₂]⁺ and [R₂NS(O)F₂]⁺ with tetracoordinated sulphur. Tetracoordinated neutral dialkylaminosulphur(IV)-oxidefluorides, R₂N$\text{S}$(O)F, and amino-imino sulphur(IV)fluorides, R₂N$\text{S}$(=NR_f)F, give three-coordinated sulphur cations [R₂N$\text{S}$O]⁺] or [R₂N$\text{S}$NR_f]⁺.The three-coordinated sulphur(VI)cation [R₂NS(O)NR]₊ has also been formed.     

Synthesen im system {carbonylmetallat/ketenimin/säure}: XXX. Neue ferra- und rhenaazetidine

The metal carbonyl anions [Fe(η-C₅H₅(CO)₂]^? and [Re(CO)₅] undergo regio- and site-specific [2 + 2]-cycloadditions with the ketenimines Ph₂CCNR (R = Me, Ph) to give the (isolable) anionic complexes [L_n$\text{M{C(CPh}{}_2\text{)N(R)C}$(O)}]^? (L_nM = 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.     

Reaction des p-phenylphospholes avec le dicyclopentadienyl-difer-tetracarbonyle,synthese et etude spectrochimique des phosphaferrocenes

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 CH₃CGClAlCl₃ complex in CH₂Cl₂.With the unsubstituted phosphaferrocene, the acetylation takes place at the 2 and 3 positions (ratio $\text{2}\text{3}$ ～ $\text{85}\text{15}$) 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.     

On the possibility of a carbenium ion structure for the complexes [Os3H3(CO)9CCR2]+. Further application of the 187Os nucleus

In the ¹H NMR spectrum of the complex [Os₃H₃(CO)₉C$\text{C(CH}{}_2\text{C}$H₂]⁺ 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 ¹⁸⁷Os¹H 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 C$\text{C(CH}{}_2\text{)}{}_2\text{C}$H₂ axis in a tilted structure, with concomitant rotation of the Os₃H₃(CO)₉ moiety.     

High pressure synthesis and crystal structure of a new series of perovskite-like compounds CMn7O12 (C = Na,Ca, Cd,Sr, La,Nd)

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 ($\text{R}\text{3}$). 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 ($\text{I}\text{2}\text{m}$). 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.     

Transition metal complexes of hexaphenylcarbodiphosphorane

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^?CC ⁺P(C₆H₅)₃. Ethylenebis(triphenylphosphine)platinum and hexaphenylcarbodiphosphorane in benzene yield a platinum containing heterocycle [(C₆H₅)₃P]₂$\text{PtC[ P(C}{}_6\text{H}{}_5\text{)}{}_3\text{]P}$-(C₆H₅)₃.     

The structure of iron(III) complexes with carbamide derivatives

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 $\text{1}\text{2}$SO^2?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.     

Intramolecular metalation of PBut2Ph and PBut3 in palladium acetate complexes

Reaction of [PdCl₂(PBu^t₂Ph)]₂ with silver acetate gives the internally metalated complex [P$\text{dCH}{}_2\text{CMe}{}_2\text{P}$Bu^tPh]₂(μ-Cl)₂. This reacts with TlC₅H₅ and LiC₅Me₅ with chloride-bridge cleavage to yield C₅R₅P$\text{dCH}{}_2$PBu^tPh (R = H, Me). The complex [P$\text{dCH}{}_2\text{CMe}{}_2\text{P}$Bu^t₂]₂(μ-Cl)₂,prepared from [PdCl₂(PBu^t₃)]₂ and CH₃COOAg, is analogously converted into C₅R₅$\text{PdCH}{}_2\text{CMe}{}_2\text{P}$Bu^t₂. The chloride complex C₅H₅Pd(PBu^t₅Ph)CI does not eliminate HCl to form C₅H₅P$\text{dCH}{}_2\text{CMe}{}_2\text{P}$Bu^tPh.