Aluminum chloride s. a. under

Aluminum chloride (s. a, under Li[AlHJ) C-Alkylation of arenes with phosphorus esters... 

Aluminum chloride s. a. under (CH CO)2P Aluminum chloride sodium chloride 4-Hydroxycoumarin ring closure... 

The behavior of such activated halides as alkylating agents under Friedel-Crafts conditions expands the scope of the synthesis. Aluminum chloride enhances the electrophilic character of the a,/S-unsaturated carbonyl system and permits the nucleophilic attachment of the aromatic addendum (Y ) to the carbon bearing the positive charge, with displacement of halogen [Eq. (5)]. Thus,... 

Reactions involving sulfur-linked substituents have been exclusively dealkylations of S-alkyl substituents to yield a thiocarbonyl group. Debenzyl-ations under mild conditions with aluminum chloride in benzene were mentioned earlier (Section IV,A,2,a). Pyridine demethylates salts 137 selectively to give 175. ° ... 

In a dry-box, a magnetic stirring bar and 32.3 g. (0.242 mole) of aluminum chloride, A1C13, are placed in a 500-ml., round-bottomed flask fitted with a 35/25 ball joint. The capped flask is removed from the dry-box and quickly attached to an addition funnel containing ether under low nitrogen pressure ( -l p.s.i.). 

The reaction of 1,3-cyclohexadiene with la at a temperature of — 50 °C gives a 97 3 mixture of 1,4-allylsilylated product, trara-3-allyl-6-(trimethylsilyl)cyclohexene and 1,2-allylsilylated product, trara-3-allyl-4-(trimethylsilyl)cyclohexene, in quantitative yield. At the same temperature, the [3 + 2] cycloaddition product is detected only in trace amounts after lh. As the reaction mixture is warmed to —10 °C, the allylsilylated compounds are converted to the [3 + 2] cycloaddition product (72%). When purified tra ,s-3-allyl-6-(trimethylsilyl)cyclohexene and tra ,s-3-allyl-4-(tri-methylsilyl)cyclohexene are treated separately under the same reaction conditions, the former compound is converted to the [3 + 2] cycloaddition product (major) and 3-(trimethylsilyl)propylbenzene [Eq. (11)], while the latter compound is converted to polymeric materials without giving any [3 + 2] cycloaddition product. The reaction rates of allylsilylation and [3 + 2] annulation are also accelerated by the addition of trimethylchlorosilane to aluminum chloride, as observed in other allylsilylation reactions.14,15... 

Preparation. The reagent is prepared by reaction of trimethylamine with diborane or with borine carbonyl (BHjCO). In a new procedure developed by Ethyl Corp, an activated aluminum powder and aluminum chloride are added to a solution of triphenyl borate in trimethylamine and the mixture is agitated at 180° under 2,000 p.s.i. of hydrogen. 

The catalyzed Diels-Alder reaction of nonauxiliary-controlled homodienophiles has received much less attention than the auxiliary-controlled one. Systematic studies of aluminum chloride catalyzed addition of acyclic dienes 2 to substituted cyclohexenones l4 and 7 s have been undertaken. The nature of the substituent exerts a strong influence on the steric course of the reaction addition of the diene taking place from the less hindered face of the dienophile, anti to the substituent. The effect is stronger for 5- than for 4-substituted cyclohexenones. For some adducts cisjtrans isomerization under these reaction conditions has been observed4,5. 

To a solution of cw-a-decalol (14,1.5 g, 9.9 mmol) in dry benzene (150 mL) and dry acetone (100 mL) was added aluminum z-propoxide (3.0 g, 14.7 mmol). The mixture, protected with a calcium chloride drying tube, was refluxed for 12 h. The reaction mixture was allowed to cool to ambient temperature and washed with 30% sulfuric acid (2 100 mL) and water until neutral. The organic extract was dried over anhydrous sodium sulfate and the solvent evaporated under reduced pressure. Fractional distillation of the product gave c/ s-a-decalone (15, 1.2 g, 80%) as a colorless oil (b.p. 116 °C (18 mmHg)) d2° 1.4939. 

When, for instance, acetonitrile56 is heated with an equimolar amount of dry potassium methoxide at 140° for 5 h, it affords 70% of 4-amino-2,6-dimethylpyrimidine ( cyano-methine ), but 85% of 2,4,6-tris(dichloromethyl)-s-triazine is obtained from dichloroaceto-nitrile in the presence of aluminum chloride and hydrogen chloride at room temperature.57 Benzonitrile trimerizes in an acid catalysed reaction, most simply when its solution in chloro-sulfonic acid is kept at 0° for 1-2 days, giving 2,4,6-triphenyl-s-triazine (cyaphenin),58 but 85% of l,2-dihydro-2,2,4,6-tetraphenyl-s-triazine is formed under the influence of a sodium suspension.59... 

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