Conjugation reactions compounds

Conidine — see 1-A2abicyclo[4.2.0]octane Conjugation reactions nitrogen heterocycles at carbon, 1, 239 at nitrogen, 1, 234-238 Conjunction nomenclature, 1, 37 Contagious bovine pleuropneumonia heterocyclic compounds as, 1, 205 A Convention... 

Comparison of the reactivity of conjugated ynaminocarbonyl compounds (N—C —C=0), their vinylacetylene analogs (N—C —C=C—C=0), and acetylenic ketones (C —C=0) in the heterocyclization reactions provides evidence for the highest activity of the former (92KGS867). 

Lewis-acid catalyzed inverse electron-demand Diels-Alder reactions between conjugated carbonyl compounds and simple alkenes and enolethers also allow dihydropyranes to be prepared. SnCU-Catalyzed cycloaddition of... 

In certain cases, Michael reactions can take place under acidic conditions. Michael-type addition of radicals to conjugated carbonyl compounds is also known.Radical addition can be catalyzed by Yb(OTf)3, but radicals add under standard conditions as well, even intramolecularly. Electrochemical-initiated Michael additions are known, and aryl halides add in the presence of NiBr2. Michael reactions are sometimes applied to substrates of the type C=C—Z, where the co-products are conjugated systems of the type C=C—Indeed, because of the greater susceptibility of triple bonds to nucleophilic attack, it is even possible for nonactivated alkynes (e.g., acetylene), to be substrates in this... 

In the presence of a base such as l,4-diazabicyclo[2.2.2]octane (DABCO) or tri-alkylphosphines, conjugated carbonyl compounds such as esters and amides add to aldehydes via the a-carbon to give a-alkenyl-P-hydroxy esters or amides. This sequence is called the Baylis-Hillman reaction and a simple example is... 

Ordinary Grignard reagents react with a, -unsaturated carbonyl compounds and afford both 1,2-adduct and 1,4-adduct. However, methylsulfonyhnethylmagnesium bromide or p-tolylsulfonylmethylmagnesium bromide gave only 1,2-adducts in the reaction with conjugated carbonyl compounds such as crotonaldehyde, cinnamaldehyde, trans-4-phenyl-3-buten-2-one, benzalacetophenone and l,5-diphenyl-2,4-pentadien-l-one. 

The hydrocyanation of conjugated carbonyl compounds is a related reaction.83 Very often such a conjugated addition is carried out in aqueous conditions. For example, in the pioneer work of Lapworth, hydrocyanation of activated olefins was carried out with KCN or NaCN in aqueous ethanol in the presence of acetic acid (Eq. 10.36).84... 

Amine functionalities also may be created on polysaccharides (Section 4.3, this chapter). The reducing ends of carbohydrate molecules (or generated aldehydes) may be reacted with small diamine compounds to yield short alkylamine spacers that can be used for subsequent conjugation reactions. Hydrazide groups may be similarly created using f z s-hydrazide compounds (Sections 4.5 and 4.6, this chapter). 

Figure 1.70 AMBH is a hydrazide-containing compound that reacts with carbonyl groups to form hydrazone bonds. The free thiol can be used for subsequent conjugation reactions.

Figure 18.25 Amino-PEG -carboxylate compounds contain a primary amine on one end and a carboxylate group on the other end. They can be used to add water-soluble spacer arms to molecules or surfaces. Using an amine-reactive group, the amino-PEG -carboxylate compound can be coupled via an amide bond, thus leaving the carboxylate end free for further conjugation reactions. Avoid the use of single-step EDC conjugation reactions, as this will polymerize the amino-PEGK-carboxylate by reacting with both ends.

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