Electrophiles acylation

Friedel-Crafts acylation of 5-acyl-56/-dibenz[6,/]azepines, e.g. 3, affords the 5,10-diacyl derivatives, e.g. 4.32 Curiously, 5-methyl-5//-dibenz[6,/]azepine is unreactive towards electrophilic acylation and only trace amounts of a product, identified tentatively as 2,8-diacetyl-5// dibenz[6,/]azepin-10-one, have been isolated. 

Aromatic electrophilic acylations were described only in the coordination sphere of the phospholide anion involving phosphacymantrenes [43, 44] or phosphaferrocenes [45],... 

The reaction of (cyclobutadiene)metal complexes with X2 results in the oxidative decomplexation to generate either dihalocyclobutenes or tetrahalocyclobutanes. In comparison, substitution of (cyclobutadiene)MLn complexes 223 [MLn = Fe(CO)3, CoCp, and RhCp] with a variety of carbon electrophiles has been observed (equation 34)15. Electrophilic acylation of 1-substituted (cyclobutadiene)Fe(CO)3 complexes gives a mixture of regioisomers predominating in the 1,3-disubstituted product and this has been utilized for the preparation of a cyclobutadiene cyclophane complex 272 (equation 35)246. For (cyclobutadiene)CoCp complexes, in which all of the ring carbons are substituted, electrophilic acylation occurs at the cyclopentadienyl ligand. 

Scheldt and co-workers have also illustrated the oxidation of activated alcohols to esters [132], Oxidations of alcohols such as 260 provide the electrophile (acyl donor) for a nucleophilic alcohol 261. Esters 262 are derived from propargylic, allylic, aromatic, and hetero-aromatic substrates (Table 20). The nucleophilic alcohol scope includes MeOH, n-BuOH, f-BuOH, 2,2,2-trichloroethanol, 2-methoxyethanol, and 2-(trimethylsilyl) ethanol. 

The amino group at tetrazole C-5 behaves as a normal nucleophile towards electrophilic acylating agents but acylation may also occur at the tetrazole N-1 or N-2 positions often giving ring degra-... 

Irreversible inhibitors act by covalently modifying the enzyme, generally at the active site. The active site is then blocked, and the enzyme is permanently rendered inactive. Because functional groups in the active site tend to be electron rich and nucleophilic, irreversible inhibitors tend to be electrophiles. Acylation agents are especially common. 

Another method is to use a much less electrophilic acylating agent than an ester. This sounds crazy but DMF 20 reacts directly with organo-lithium compounds to give good yields of aldehydes... 

The reactive electrophilic acyl and carbonyl compounds produced by oxidative dehalogenation may react with nucleophilic biological molecules such as DNA, proteins, lipids and carbohydrates to possibly form toxic metabolites. 

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