Gold(I)/Chiral N,N′‐Dioxide–Nickel(II) Relay Catalysis for Asymmetric Tandem Intermolecular Hydroalkoxylation/Claisen Rearrangement

A highly efficient asymmetric cascade reaction between alkynyl esters and allylic alcohols has been realized. Key to success was the combination of a hydroalkoxylation reaction catalyzed by a π‐acidic gold(I) complex with a Claisen rearrangement catalyzed by a chiral Lewis acidic N,N′‐dioxide–nickel(II) complex. A range of acyclic α‐allyl β‐keto esters were synthesized in high yields (up to 99 %) with good diastereoselectivities (up to 97:3) and excellent enantioselectivities (up to 99 % ee ) under mild reaction conditions. These products can be easily transformed into optically active β‐hydroxy esters, β‐hydroxy acids, or 1,3‐diols.     

Enantioselektive Verseifung der Diacetate von 2-Nitro-1,3-diolen mit Schweineleber-Esterase und Herstellung enantiomerenreiner Derivate von 2-Nitro-allylalkoholen (chirale Verknüpfungsreagenzien)

Enantioselective Saponification of Diacetates of 2-Nitro-1,3-propanediols by Pig-Liver Esterase and Preparation of Enantiomerically Pure Derivatives of 2-Nitro-allylic Alcohols (Chiral Multiple-Coupling Reagents) The reproducible enantioselective saponification of open-chain and cyclic diacetates of meso-2-nitro-1,3-propanediols (see 4b – 13b ) with pig-liver esterase (PLE) gives monoacetates (see 4c – l3c ) of > 95% enantiomeric excess. The Re enantiotopic acetate group appears to be saponified preferentially, as proved by the X-ray crystal structure analysis of three camphanoates 4d , 6d , and 7d . Elimination of H₂O or AcOH from the hydroxy acetates thus available gives derivatives of nitro-allylic alcohols (see 20 – 24 , 27 , and 29 ) which are subjected to diastereoselective Michael additions or S_N2′ substitutions.     

Synthesis,characterization and crystal structure of a manganese(III) Schiff base complex and investigation of its catalytic activity in the oxidation of benzylic alcohols

A new Mn(III) Schiff base complex was prepared by the reaction of 6,6′-diethoxy-2,2′-[2,2-dimethylpropane-1,3-diylbis(nitrilomethylidyne)]diphenol with Mn(OAc)₂·4H₂O. The complex was characterized by physicochemical and spectroscopic methods. Also, its molecular structure was determined by single-crystal X-ray diffraction. The complex was used as a catalyst for the efficient oxidation of benzylic alcohols with tetrabutylammonium periodate. Various reaction parameters were optimized for the reaction of benzyl alcohol.     

A CARBON-13 NMR STUDY OF POLAR-(NITRO)TRIMETHYLENEDIAMINE-N,N,N′-TRIACETATOCOBALTATE(III) ION

Abstract

The complex ion [Co(1,3-pd3a)NO₂]^? (pd3a=trimethylenediamine-N,N,N′-triacetate ion) was prepared from equatorial-skew-[Co(1,3-pd3a)H₂ O]. The absorption spectrum and the ¹³C NMR spectrum show the nitro product to be a polar isomer. The diamine backbone ring is believed to have the chair conformation.     

Halogenation of Fluorinated 1,3,5‐Triketones

The behavior of linear and cyclic fluorinated 1,3,5‐triketones and their metal derivatives towards common halogenating agents was examined, and optimal reaction conditions for the straightforward synthesis of mono‐, di‐, and tetrahalogenated products were found (Schemes 1–3). An aromatization through a double HBr elimination from an α,α′‐dibrominated cyclohexanone was shown to be a promising synthetic route to 1,1′‐(2‐hydroxy‐1,3‐phenylene)bis[2,2,2‐trifluoroethanones] (= 2,6‐bis(trifluoroacetyl)phenols; Scheme 4). Additionally, the 1,3,5‐triketones prepared add readily H₂O or alcohols to produce novel bridged 2,6‐dihydroxypyran‐4‐ones (Scheme 2). The structure of the obtained compounds 6a and 7a was confirmed by X‐ray structure analysis.     

Poly(N,N′-dichloro-N-ethyl-benzene-1,3-disulfonamide, N,N,N′,N′-tetrachlorobenzene-1,3-disulfonamide, poly(N,N′-dibromo-N-ethyl-benzene-1,3-disulfonamide, and N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide catalyzed formylation of amines and alcohols using ethyl formate under microwave irradiation

A simple, rapid, and efficient procedure for formylation of primary and secondary amines and alcohols using ethyl formate catalyzed with poly(N,N′-dichloro-N-ethyl-benzene-1,3-disulfonamide (PCBS), N,N,N′,N′-tetrachlorobenzene-1,3-disulfonamide (TCBDA), poly(N,N′-dibromo-N-ethyl-benzene-1,3-disulfonamide (PBBS) and also N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide (TBBDA) was adopted. The reactions were performed under microwave irradiation with high yields.     

Di-radical dinuclear copper complex: synthesis,structure, and magnetic properties

The reaction of Cu(Ac)₂·4H₂O with 2-[(3,5-dichloro-2-hydroxy-benzylidene)-amino]-2hydroxymethyl-propane-1,3-diol (H₄L) and 4,4′-bipyridyl-N,N′-dioxide (4,4′-bipy-NO) in DMF under solvothermal conditions leads to the formation of a di-radical dinuclear copper complex [Cu₂(4,4′-bipy-NO)(dcdmap)₄] (1) (dcdmap is the anion of 2,4-dichloro-6dimethylaminomethyl-phenol, synthesized by an in situ reaction). Compound 1 was characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. Complex 1 displays dominant anti-ferromagnetic interaction between oxyradicals and copper ion and oxyradical.     

Synthesis and Identification of Key Biosynthetic Intermediates for the Formation of the Tricyclic Skeleton of Saxitoxin

Saxitoxin (STX) and its analogues are potent voltage‐gated sodium channel blockers biosynthesized by freshwater cyanobacteria and marine dinoflagellates. We previously identified genetically predicted biosynthetic intermediates of STX at early stages, Int‐A′ and Int‐C′2, in these microorganisms. However, the mechanism to form the tricyclic skeleton of STX was unknown. To solve this problem, we screened for unidentified intermediates by analyzing the results from previous incorporation experiments with ¹⁵N‐labeled Int‐C′2. The presence of monohydroxy‐Int‐C′2 and possibly Int‐E′ was suggested, and 11‐hydroxy‐Int‐C′2 and Int‐E′ were identified from synthesized standards and LC‐MS. Furthermore, we observed that the hydroxy group at C11 of 11‐hydroxy‐Int‐C′2 was slowly replaced by CD₃O in CD₃OD. Based on this characteristic reactivity, we propose a possible mechanism to form the tricyclic skeleton of STX via a bicyclic intermediate from 11‐hydroxy‐Int‐C′2.     

A three‐dimensional cadmium(II) coordination polymer: poly[[[μ‐4,4′‐(propane‐1,3‐diyl)dipyridine‐κ2N:N](μ‐3,3′‐thiodipropionato‐κ3O,O′:O)cadmium(II)] monohydrate]

In the title coordination polymer, {[Cd(C₆H₈O₄S)(C₁₃H₁₄N₂)]·H₂O}_n, the Cd^II atom displays a distorted octahedral coordination, formed by three carboxylate O atoms and one S atom from three different 3,3′‐thiodipropionate ligands, and two N atoms from two different 4,4′‐(propane‐1,3‐diyl)dipyridine ligands. The Cd^II centres are bridged through carboxylate O atoms of 3,3′‐thiodipropionate ligands and through N atoms of 4,4′‐(propane‐1,3‐diyl)dipyridine ligands to form two different one‐dimensional chains, which intersect to form a two‐dimensional layer. These two‐dimensional layers are linked by S atoms of 3,3′‐thiodipropionate ligands from adjacent layers to form a three‐dimensional network.     

Axially Dissymmetric Chiral (R)‐N,W‐Bis(2‐hydroxy‐3,5‐ditert‐butyl‐arylmethyl)‐1, 1′‐binaphthalene‐2,2′‐diamine as Chiral Ligands in the Reaction of Diethylzinc to Aldehydes†

Chiral ligand (A)‐N,N′‐Bis(2‐hydroxy‐3,5‐di‐tert‐butyl‐arylmethyl)‐1,1′‐binaphthalene‐2,2′‐diamine derived from the reduction of Schiff base (R)‐2,2′‐bis (3,5‐di‐tert‐butyl‐2‐hydroxybenzylideneamino)‐1, 1′‐binaphthyl with LiAlH₄, is fairly effective in the asymmetric addition reaction of diethylzinc to aldehydes by which good yields (46%‐94%) of the corresponding sec‐alcohols can be obtained in moderate ee (51%‐79%) with R configuration for a variety of aldehydes.     

(±)‐6‐tert‐Butyl‐8‐hydroxymethyl‐2‐­phenyl‐4H‐1,3‐benzodioxin and 2,2,2′,2′,6,6′‐hexamethyl‐8,8′‐methylenebis(4H‐1,3‐benzodioxin)

Two compounds containing 1,3‐benzodioxin groups are reported, namely (±)‐6‐tert‐butyl‐8‐hydroxy­methyl‐2‐phenyl‐4H‐1,3‐benzodioxin, C₁₉H₂₂O₃, (I), and 2,2,2′,2′,6,6′‐hexamethyl‐8,8′‐methyl­enebis(4H‐1,3‐benzodioxin), C₂₃H₂₈O₄, (II).The hydroxy groups of neighbouring mol­ecules in (I) are hydrogen bonded to each other, giving rise to double‐row chains. The mol­ecule in (II) adopts a `butterfly' conformation, with the O atoms in distal positions. In both compounds, the dioxin rings are in distorted half‐chair conformations.     

Spectroscopic Characterization of Some Tetradentate Schiff Bases and Their Complexes with Nickel,Copper and Zinc

Three ligands have been formed by the 1:2 molar condensation of o‐phenylenediamine with salicyldhyde, 2‐hydroxy‐1‐naphthaldhyde or o‐hydroxyacetophenone. The potentially tetradentate ligands are N,N′‐bis(salicyldhyde)‐o‐phenylenediamine(SalophH₂), N,N′‐bis(2‐hydroxy‐1‐naphthaldhyde)‐o‐phenylenediamine (NophH₂) and N,N′‐bis(o‐hydroxyacetophenone)‐o‐phenylenediamine (AophH₂), respectively. These ligands form complexes (1:1 molar ratio) with nickel, copper and zinc ions. The complexes have been characterized by IR, ¹HNMR, MS, uv/vis spectra in addition to elemental analysis. The spectral data of the ligands and their complexes with nickel, copper and zinc are discussed in connection with the structural changes which occur due to complexation.     

不同双/多齿配体Co(Ⅱ)配合物的氧合性能

在室温水溶液体系中采用紫外-可见分光光度法和氧电极法对比研究了α-氨基酸(N/O型)、α-氨基醇(N/O型)、羟基多元羧酸(O/O型)和多胺(N/N型)这4类不同双/多齿配体的Co(Ⅱ)配合物的氧合性能及其氧合反应的可逆性.结果表明, O/O型含羟基的羧酸Co(Ⅱ)配合物无氧合性能; N/N型多胺Co(Ⅱ)配合物有强吸氧性, 但氧合反应不可逆; N/O型配体的Co(Ⅱ)配合物的氧合性能差异较大, 其中α-氨基酸Co(Ⅱ)配合物具有明显的可逆氧合性能, 而含1个—OH的α-氨基醇Co(Ⅱ)配合物没有吸氧能力, 含有2个—OH的α-氨基醇Co(Ⅱ)配合物有微弱的吸氧能力但氧合反应不可逆.分析探讨了N/O型配体中—OH和—COOH对Co(Ⅱ)配合物可逆吸氧性能影响的机理, 根据实验结果初步认为α-氨基酸配位结构是Co(Ⅱ)配合物具有可逆吸氧性能的基本配位结构单元.     

N,N,N′,N′‐Tetrabromobenzene‐1,3‐Disulfonamide and Poly(N‐Bromo‐N‐Ethyl‐Benzene‐1,3‐Disulfonamide) as Efficient Catalysts for the Methoxymethylation of Alcohols under Solvent‐Free Conditions

Methoxymethylation of a variety of alcohols was performed using formaldehyde dimethyl acetal in the presence of N,N,N′,N′‐tetrabromobenzene‐1,3‐disulfonamide [TBBDA] and poly(N‐bromo‐N‐ethylbenzene‐1,3‐disulfonamide) [PBBS] as catalysts at room temperature and solvent‐free conditions. The methoxymethyl ethers (MOM‐ethers) were obtained with good to excellent yields.     

Synthesis of <Emphasis Type="Italic">N,N′</Emphasis>-bis-[3-alkoxy-4-(hydroxy,alkoxy, acyloxy)-phenylmethylene- and -Phenylmethyl]-1,3-phenylenediamines

Starting with the vanillin series aldehydes, by reaction with 1,3-phenylenediamine in absolute methanol E,E-N,N′-bis-[3-alkoxy-4-(hydroxy-, alkoxy-, acyloxy)phenylme-thylene]-1,3-phenyl-enediamines (Shiff bases) are synthesized from reduction with Na[BH(OAc)₃] in benzene were prepared respective N,N′-bis-[3-alkoxy-4-(hydroxy-, alkoxy-, acyloxy)phenylmethyl]-1,3-phenyl-enediamines.     

The synthesis of novel acetolactate synthase inhibitors,N‐(asymmetrically disubstituted phosphoryl)‐N′‐(4,6‐dimethoxypyrimidin‐2‐yl) ureas

In view of the isosterism of the sulfonyl group(‐SO₂‐) and the phosphoryl group, two new types of compounds N‐(N‐aryl‐O‐alkyl phosphoryl)‐N′‐(4,6‐dimethoxypyrimidin‐2‐yl) ureas (2) and N‐(N‐aryl‐N‐alkylphosphoryl)‐N′‐(4,6‐dimethoxypyrimidin‐2‐yl) ureas (3) were designed and synthesized by treating N‐(arylaminochlorophosphoryl)‐N′‐(4,6‐dimethoxypy‐rimidinyl‐2‐) ureas (4) with alcohols or amines. Compounds 4 were obtained by treating dichloro‐phosphoryl isocyanate with 4,6‐dimethoxy‐2‐amino‐pyrimidine and then with aromatic amines. The enzyme tests in vitro indicated that compounds 2 and 3 were two novel classes of acetolactate synthase (ALS) inhibitors and also showed that phosphoryl groups[‐P(O)(OR)‐, R=alkyl] and [‐P(O)(NHR), R=alkyl] were likely to be good bioisosteres of the sulfonyl group (‐SO₂‐) in the sulfonylureas. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10:237–241, 1999     

Aerobic alcohol oxidation catalyzed by a new, oxygen-bridged heterometallic compound [PPh4][Ru(N)Me2(μ2-O)2Pd((−)-sparteine)]

The reaction between the new hydroxy compound [PPh₄][Ru(N)(OH)₂Me₂] and Pd(OSiMe₃)₂((−)-sparteine) produces (Me₃Si)₂O, H₂O and a new heterobimetallic compound [PPh₄][Ru(N)Me₂(μ₂-O)₂Pd((−)-sparteine)] in good yield. The Ru/Pd bimetallic compound catalyzes the oxidation of aryl and allyl alcohols to the corresponding carbonyl compound in air and the rearrangement of allylic alcohols unsaturated aldehydes. It also oxidizes PPh₃ to O-PPh₃ under O₂.     

(2R*,4S*)‐2‐(Pyridin‐3‐yl)‐2,3,4,5‐tetrahydro‐1H‐1‐benzazepin‐4‐ol: a three‐dimensional framework built from O—H...N,C—H...O and C—H...π(arene) hydrogen bonds

The title compound, C₁₅H₁₆N₂O, crystallizes in the space group P2₁2₁2₁ with Z′ = 1. The seven‐membered ring adopts a chair‐type conformation with the hydroxy and pyridyl substituents in equatorial sites. Molecules are linked into a three‐dimensional framework structure by a combination of O—H...N, C—H...O and C—H...π(arene) hydrogen bonds, but N—H...O and N—H...π(arene) interactions are absent from the structure. Comparisons are made with some related compounds.     

Mono-, di-, and tetra-aurated derivatives of barbituric acid,including a new type of polynuclear gold compound. Crystal structure of 1,3-bis(triphenylphosphinegold)-5,5-diethylbarbituric acid

Reaction of barbituric acid (2,4,6-pyrimidinetrione) or its derivatives with LAuCl (L = triphenylphosphine) gave 3-LAu-5,5-diethyl-, 1,3-(L'Au)₂-5,5-diethyl- (L′ = L or L′ = Cy₃P), 1,3-dimethyl-5,5-bis(LAu)-, or 1,3,5,5-tetrakis-(LAu)barbituric acid, which were characterized as N-, N,N′-, C,C′-, or N,N′,C,C-gold derivative,s respectively, by IR, ¹H, ¹³C and ³¹P NMR spectroscopy. In the case of 1,3-(LM)(L″M)-5,5-diethylbarbituric acid compounds with M = gold and L″ either Cy₃P, Ph₃As, or (4-tolyl)₃P, or ML = ML″ = HgMe were prepared. An X-ray diffraction study of 1,3-(LAu)₂-5,5-Et₂-pyrimidin-2,4,6-trione · 3C₆H₆ revealed that (a) the heterocyclic ring is planar, (b) there is no inter- or intra-molecular Au ⋯ Au interaction, and (c) the coordination around each gold atom is approximately linear (PAuN 178.3(4)°, with AuN 2.022(12) and AuP 2.233(5) Å. The molecular parameters are compared with those for barbituric acid and other barbiturates.     

Novel hydrazone derivatives of 7‐hydroxy‐3′,3′‐dimethyl‐3′H‐spiro[chromene‐2,1′‐isobenzofuran]‐8‐carbaldehyde

The structures of new oxaindane spiropyrans derived from 7‐hydroxy‐3′,3′‐dimethyl‐3′H‐spiro[chromene‐2,1′‐isobenzofuran]‐8‐carbaldehyde (SP1), namely N‐benzyl‐2‐[(7‐hydroxy‐3′,3′‐dimethyl‐3′H‐spiro[chromene‐2,1′‐isobenzofuran]‐8‐yl)methylidene]hydrazinecarbothioamide, C₂₇H₂₅N₃O₃S, (I), at 120 (2) K, and N′‐[(7‐hydroxy‐3′,3′‐dimethyl‐3′H‐spiro[chromene‐2,1′‐isobenzofuran]‐8‐yl)methylidene]‐4‐methylbenzohydrazide acetone monosolvate, C₂₇H₂₄N₂O₄·C₃H₆O, (II), at 100 (2) K, are reported. The photochromically active C_spiro—O bond length in (I) is close to that in the parent compound (SP1), and in (II) it is shorter. In (I), centrosymmetric pairs of molecules are bound by two equivalent N—H...S hydrogen bonds, forming an eight‐membered ring with two donors and two acceptors.