Conjugated compounds with acylation

While a large number of studies have been reported for conjugate addition and Sn2 alkylation reactions, the mechanisms of many important organocopper-promoted reactions have not been discussed. These include substitution on sp carbons, acylation with acyl halides [168], additions to carbonyl compounds, oxidative couplings [169], nucleophilic opening of electrophilic cyclopropanes [170], and the Kocienski reaction [171]. The chemistry of organocopper(II) species has rarely been studied experimentally [172-174], nor theoretically, save for some trapping experiments on the reaction of alkyl radicals with Cu(I) species in aqueous solution [175]. 

Also in the case of intennediate 374, a lithium-copper transmetallation with a copper(I) halide (bromide or chloride) allowed one to carry out the conjugate addition [to electrophilic olefins R CH = CH2Z (Z = COR, CO2R) giving compounds 381 in 31-76% yield], the acylation (with acyl chlorides yielding ketones 382 in 35-65% yield) and dimerization [using copper(II) chloride as the additive, to give compound 383 in 59% yield] processes ... 

The simple furan-3(2/f)-ones exist in the keto form but may be O-acylated with acetic anhydride and sodium acetate however, they undergo C-alkylation. They are usually stable to acid, merely being protonated. 4-Alkoxyfuran-3(2//)-ones are readily hydrolyzed to tetronic acids. Furan-3(2//)-ones are degraded by aqueous base which attacks in a conjugate fashion so that 2,5-dimethylfuran-3(2iT)-one, readily available from biacetyl, furnishes acetate and acetoin, but compounds with an ester group at the 4-position furnish tetronic acids (Scheme 109). 

In combinatorial chemistry, the development of multicomponent reactions leading to product formation is an attractive strategy because relatively complex molecules can be assembled with fewer steps and in shorter periods. For example, the Ugi multicomponent reaction involving the combination of an isocyanide, an aldehyde, an amine, and a carboxylic acid results in the synthesis of a-acyl amino amide derivatives [32]. The scope of this reaction has been explored in solid-phase synthesis and it allows the generation of a large number of compounds with relative ease. This reaction has been employed in the synthesis of a library of C-glycoside conjugated amino amides [33]. Scheme 14.14 shows that, on reaction with carboxylic acids 38, isocyanides 39, and Rink amide resin derivatized with different amino acids 40, the C-fucose aldehyde 37 results in the library synthesis of C-linked fucosyl amino acids 41 as potential mimics of sialyl Lewis. ... 

Just as anions of allyl derivatives can be homoenolate equivalents (chapter 13) so anions of vinyl derivatives can be acyl anion equivalents. Vinyl (or enol) ethers can be lithiated reasonably easily, especially when there is no possibility of forming an allyl derivative, as with the simplest compound 81. The most acidic proton is the one marked and the vinyl-lithium derivative 82 reacts with electrophiles to give the enol ether of the product17 84. However, tertiary butyl lithium is needed and compounds with y-CHs usually end up as the chelated allyl-lithium 85. These vinyl-lithium compounds add directly to conjugated systems but the cuprates will do conjugate addition.18... 

Conjugate addition of acyl groups to a,fl-unsaturated carbonyl compounds.3 Nickel carbonyl forms unstable complexes with organolithium compounds (ether,... 

Addition reactions. Asymmetric allyl transfer from allyl boronates to A-acyl imines is assisted by (5)-3,3 -diphenyl-BINOL Alkenyldimethoxyboranes react with conjugated carbonyl compounds with excellent enantioselectivity in the presence of a chiral 3,3 -diiodo-BINOL. ... 

Nucleophiles form nucleophilic acyl substitution products with a,j8-unsaturated Class I carbonyl compounds that have reactive carbonyl groups and conjugate addition products with compounds with less reactive carbonyl groups. 

Oxidation causes the formation of hydroperoxides and conjugated compounds, which by cleavage give aldehydes, alcohols, ketones, lactones, acids, esters, and hydrocarbons. Radical mechanisms lead to the formation of dimers, other oligomers, and oxidized TAG. The latter have one or more acyl group with an extra oxygen (hydroxy, keto, epoxy derivatives). Other oxidation products are TAG with short-chain fatty acyl and n-oxo fatty acyl groups. 

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