O-Chlorophenyl group

The enantioselective photoreaction of 50 to 52 in the complex (57) can be interpreted as follows disrotatory [2 + 2]-photoreaction of 50 in 51 occurs only in the A direction according to a steric hindrance of the o-chlorophenyl group of 2a (Scheme 4)29 30). This interpretation was determined as reasonable by X-ray crystal structural study of 51b (Fig. 12)32). 

Homoeyelic ring closures. Bunnett and Skorcz31 found that several aliphatic esters, nitriles, sulfones, and ketones bearing an m-o-chlorophenyl group react with potassium amide in liquid ammonia to form homocyclic products of ring closure by way of a benzyne intermediate. The procedure has since been modified to use sodium amide (commercially available).32 The reaction is probably the method of choice for synthesis of 1 -substituted benzcyclobutenes. 

In the case of aromatic isocyanates, electron-withdrawing groups increase the rate of carbodiimide formation in proportion to their electron-withdrawing power. Electron-releasing groups tend to inhibit the reaction. p-Nitrophenyl isocyanate reacts almost explosively to yield the carbodiimide when catalyzed [5]. o-Chlorophenyl isocyanate reacts seven times as fast as the o-methyl analog [33]. 

A solution of 400 g of co-bromo-o-chloroacetophenone in one liter of methanol was cooled to about 25°C. A cold solution of 92.5 g of sodium borohydride in one liter of methanol was added as rapidly as possible to this cooled solution while maintaining the temperature below about 25°C. After the addition had been completed, the reaction mixture was allowed to stand for 4 hours at ambient room temperature, to complete the reduction of the keto group of the (o-bromo-o-chloroacetophenone. The reaction mixture containing a mixture of o-chlorophenyl ethylene-p-bromohydrin and o-chlorophenyl ethylene oxide was then evaporated in vacuo at room temperature to a syrup which was poured into about one liter of 5% hydrochloric acid to decompose any borate-alcohol complexes. 

The efficiency of the resolution is dependent on the Ar and R groups, being highest when Ar is m-tolyl and R is CH3 or C2H5. No complex is formed when Ar is C6H5 and R is CH3 or from dialkyl sulfoximines. However, some dialkyl sulfoximines can be resolved with ( + )- or (-)-3, 1,6-di(o-chlorophenyl)-l, 6-diphenylhexa-2,4-diyne-l,6-diol. This reagent is available commercially as Chiral Host Ace.2... 

The Truce-Smiles rearrangement is general for diaryl sulfones containing an o-methyl group and involves benzylic deprotonation to the anion which subsequently rearranges to the sulfinate. If the sulfinate contains a suitably placed leaving group, further reactions may occur for example, the chlorophenyl sulfone (114) forms the sulfinate (115), but this... 

R1 = 3 -protecting group, e.g. acetyl, or a linkage to the polymer support R2 = phosphorus protecting group, e.g. o-chlorophenyl for II or /3-cyanoethyl for III... 

The Chapman rearrangement provides an elegant synthesis of unsymmetrical diarylamines that are otherwise difficult of access. When aryl JV-arylbenz-imidoates are heated, the O-aryl group migrates to nitrogen while the double bond moves from the N=C to the C=0 position. For example, 2,4,6-tri-chlorophenyl iV-(o-chlorophenyl)benzimidoate is converted quantitatively into A-(0-chlorophenyl)-jV-(2,4,6-trichlorophenyl)benzamide when heated for... 

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