Active hydrogen compounds acylation

Reaction between acyl halides and active hydrogen compounds... 

Acylation of active hydrogen compounds followed by cleavage... 

Enol Ethers and Esters 0-15 O-Alkylation of carbonyl compounds with diazo alkanes 0-17 Transetherification 0-20 Reaction between acyl halides and active hydrogen compounds 0-23 Transesterification 0-24 Acylation of vinylic halides 0-94 Alkylation with ortho esters 0-107 O-Acylation of 1,3-dicarbonyl compounds... 

Acylation of active hydrogen compounds followed by cleavage 0-109 Reduction of p-keto sulfoxides 0-110 Acylation of carboxylic acid salts followed by cleavage... 

The acetoacetic ester condensation (involving the acylation of an ester by an ester) is a special case of a more general reaction term the Claisen condensation. The latter is the condensation between a carboxylic ester and an ester (or ketone or nitrile) containing an a-hydrogen atom in the presence of a base (sodium, sodium alkoxide, sodamide, sodium triphenylmethide, etc.). If R—H is the compound containing the a- or active hydrogen atom, the Claisen condensation may be written ... 

The radical C-H transformation of ethers is generally initiated by a-hydrogen abstraction with highly reactive radicals generated from such initiators as peroxides [3a, g], photo-activated carbonyl compounds [3b—d], metallic reagents [3i, j], and redox systems [3f, h[. Various combinations of ethers, radical initiators, and radical acceptors (e.g. carbon-carbon multiple bonds) may be used as the reaction components [6], Several notable means of direct C-C bond formation via the radical a-C-H transformation of ethers involve the use of triflon derivatives [7], the phthalimide-N-oxyl (PINO) radical [8], 2-chloroethylsulfonyl oxime ethers [9], and N-acyl aldohydrazones [10],... 

Highly activated aromatic compounds such as dihydric phenols can be acylated by reaction with an aliphatic nitrile in the presence of a Lewis acid, usually zinc chloride, and hydrogen chloride (Scheme 6.24). The Houben-Hoesch reaction is a variation of the Gattermann formylation and proceeds via an iminium salt, which is isolated and subsequently hydrolysed. 

A number of recent reviews exist about intermolecular and intramolecular reactions of the iV-acyl-iminium intermediate. Moreover, detailed accounts of the application in alkaloid synthesis have recently appeared. This chapter deals with reactions of species (1) with nucleophilic alkenes (and alkynes). Other synthetically useful nucleophiles like aromatic rings, active methylene compounds and organome-tallics will not be discussed here. In (1) R, and R are hydrogen or carbon substituents, and R may also be a hetero substituent, such as alkylamino or alkoxy. This chapter differs from previous reviews, as the material is ordered here on the basis of the structural features of the A -acyliminium intermediate. Major emphasis is placed on recent developments and stereochemical details. 

GC Derivatization is usually carried out to increase the volatility of substances that exhibit high boiling points or molecules that are thermally unstable and may decompose in the inlet port. Derivatization frequently makes it possible to resolve compounds. A derivatization reaction is performed prior to injection to make the solute more volatilizable. Each class of reactions replaces the active hydrogen of OH, NH, or SH. Alkylation, silylation, or acylation are very easily performed. Reagents are sold in vials to carry out the reaction. According to the type of solute different reagents are available. 

Acylation converts compounds with active hydrogen, for example, in the -SH into thioesters by reaction with carboxyl acids or their derivatives. The presence of a carbonyl group next to the halogenated carbon increases the ECD response. For thiols, using Af-methyl-bis(trifluoroacetamide) (MBTFA) is recommended. 

Transition-metal acetylides react readily with metal carbonyls to form derivatives. Thus (7t-Cp)2Ti(C CPh)2 and Ni(CO)4 afford (22). The oxidative additions of alkyl and acyl halides, RCOCl (R = Me or Ph), to [(7i-Cp)2Ti(CO)2] yield the corresponding [(7i-Cp)2Ti(Cl)C(0)R] compounds, and 9,10-phenanthraquinone affords (23). [(7i-Cp)2TiPh2] and [(7t-Cp)2 Ti(Me)Cl] have been shown to be active hydrogenation catalysts and the n.m.r. spectra of several [(7t-Cp)2TiR2] and [(7i-Cp)2Ti(R)Cl] compounds have been re-investigated and previous interpretations of such data questioned. ... 

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