4-methoxyphenyl complex with

It is interesting that the product distribution from the reaction of the o-methoxyphenyl complex with diethylacetylene was found to be dependent on alkyne concentration. One equivalent of alkyne, slow addition of alkyne, or low absolute concentration of alkyne favors the indene product. Reactions performed with excess or high concentrations of alkyne favor benzannulation. The observation, reffered to as the allochemical effect, was explained as resulting from coordination of reaction intermediates by the alkyne. Thus excess alkyne acts as a ligand to stabilize intermediates along the path to benzannulation. Finally, it was noted that the product distribution was not substantially altered by addition of phosphines, phosphine oxides or sulfides. 

Other complexes with bridging N,S ligands are the 1,3-dimethyl-8-thioxantine derivative [Au2(/u-N,S) /u-PMe2(CH2)2PMe2 ],3149 or with quinoline thiolates [Au5(/u-SQuin)3(//-dppm)2]2+ (604)3150 deprotonated ethylenethiourea [Au4(etu-H)4] (605)3151 or with 2-methoxyphenyl-imino(2-pyridyl)methylthio derivatives as [Au SC(Py)=NR) (PPh3)].3152... 

Ethylene, with p-methoxyphenyl-acetyl chloride and aluminum chloride to give 6-me thoxy-g-tetralone, 51, 109 Ethylenediamine, complexes with chromium(II) salts,... 

An alternative hydrazine derivative used is 3 -methyldithiocarbazate, which is reported to react with tetracya-noethylene via a charge-transfer complex, giving a mixture of polysubstituted pyridazine 9 and pyridazino[4,5-rfjpyridazine 10 <1995PS(101)189>. l,4,5,8-Tetrakis(4-methoxyphenyl)pyridazino[4,5-4]pyridazine 11 has also been prepared by cyclization of tetrakis(4-methoxyphenyl)ethane with hydrazine itself <2000RJ01157>. 

The reaction of arenes with aryllead tricarboxylates performed in trifluoroacetic acid, affording biarenes, takes place via a cationic 7t-complex.162 Since azulenes form 7r-donor/acceptor complexes with various 7r-acids, the arylation of 4,6,8-trimethylazulene 108 was attempted with />-methoxyphenyllead triacetate 1 (Equation (135)).163 Only one isomer of 1-arylazulene 109 was formed although in a modest 27% isolated yield. Based on recovered unreacted azulene, the effective yield was 43%. A dimer 110, 3,3 -dianisyl-l,l -biazulene (4% yield), was suggested to result from the one-electron oxidation of the intermediate 4-methoxyphenyl cation in the 7t-complex. 

Phenyl, 4-methoxyphenyl, and 4-ethoxyphenyl tellurium thiocyanates are known only in the form of their complexes with thiourea1,2 ethylenethiourea3, triphenylarsine oxide, 3-methylpyridine, 3-methylpyridine /V-oxidc, or 4-methylpyridine Af-oxide2. These compounds were prepared from the diaryl ditellurium compounds, thiocyanogen, and the ligands2. 

Bis[4-methoxyphenyl] tellurium dichloride formed 1 1 complexes with tributyl-, triphenyl-, and tris[4-methoxyphenyl]phosphane selenides, and 1 1 and 2 1 complexes with 1,2-bis[diphenylphosphano]ethane P,P-diselenide6. 

Similar complexes were obtained from bis[4-methoxyphenyl] tellurium diperchlorate including a 1 1 adduct with triphenylphosphane sulfide2. Adducts with two moles of ligand per mole of diaryl tellurium diperchlorate could not be obtained even from reaction mixtures containing an excess of the ligand. However, telluracyclopentane diperchlorate formed 1 2 complexes with unidentate ligands2 3 and 1 1 complexes with bidentate ligands3. 

The synthesis of 11-deoxydaunomycinone by Wulff and Xu is presented in Scheme 39 and involves the benzannulation of the non-chelated o-methoxyphenyl complex (280) with the alkyne (281). ° The utilization of a t-butyl ester in the alkyne (281) makes possible a one-pot construction of the tetracyclic dione (282) via a tandem benzannulation-Friedel-Cr ts cyclization. After the reaction between the... 

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