Conjugated compounds, 1,2-addition

Application of the cuprous chloride-catalyzed conjugate Grignard addition to A -5a-3-ketones (13) gives la-methyl compounds (14) in yields up to... 

Addition polymerization is employed primarily with substituted or unsuhstituted olefins and conjugated diolefins. Addition polymerization initiators are free radicals, anions, cations, and coordination compounds. In addition polymerization, a chain grows simply hy adding monomer molecules to a propagating chain. The first step is to add a free radical, a cationic or an anionic initiator (I ) to the monomer. For example, in ethylene polymerization (with a special catalyst), the chain grows hy attaching the ethylene units one after another until the polymer terminates. This type of addition produces a linear polymer ... 

Thus the weak n — n band in a saturated carbonyl compound is shifted from below 300 nm to above 300 nm with an increase in s. Conjugation of additional chromophoric groups moves mx progressively... 

Conjugate reduction.1 This stable copper(I) hydride cluster can effect conjugate hydride addition to a,p-unsaturated carbonyl compounds, with apparent utilization of all six hydride equivalents per cluster. No 1,2-reduction of carbonyl groups or reduction of isolated double bonds is observed. Undesirable side reactions such as aldol condensation can be suppressed by addition of water. Reactions in the presence of chlorotrimethylsilane result in silyl enol ethers. The reduction is stereoselective, resulting in hydride delivery to the less-hindered face of the substrate. 

The sequence that follows illustrates how a conjugate aldol addition (Michael addition) followed by a simple aldol condensation may be used to build one ring onto another. This procedure is known as the Robinson annulation (ring forming) reaction (after the English chemist Sir Robert Robinson, who won the Nobel Prize in Chemistry in 1947 for his research on naturally occurring compounds). 

The 18 n-electron system furo[3,4-c]octalene (356) is available by a Wittig reaction starting from cyclooctatetraene-1,2-dicarboxaldehyde it is obtained as an unstable pale yellow liquid, which is rapidly oxidized in air. The electronic spectrum resembles that of 353, showing little extended conjugation. Compound 356 underwent Diels-Alder addition at the terminal cyclooctatetraene ring thus treatment with dimethyl fumarate leads to monoadduct 357. ... 

Amphetamine is metabolized by deamination, oxidation, and hydroxylation. Figure 4.1 illustrates the metabolic scheme for amphetamine. Deamination produces an inactive metabolite, phe-nylacetone, which is further oxidized to benzoic acid and then excreted in urine as hippuric acid and glucuronide conjugates. In addition, amphetamine is also converted to norephedrine by oxidation and then this metabolite and the parent compound are / -hydroxylated. Several metabolites, including norephedrine, its hydroxy metabolite, and hydroxy amphetamine, are pharmacologically active. The excretion of amphetamine depends on urinary pH. In healthy men who were administered 5 mg of isotopically labeled d,l-amphetamine, approximately 90% of the dose was excreted... 

Cycloaddition reactions represent a very versatile route to alicyclic compounds. The most important for six-membered rings is the Diels-Alder reaction, and its great utility lies in the fact that it is both regioselective and stereospecific. The reaction involves compounds containing a double or triple bond, usually activated by conjugation with additional multiply-bonded systems (carbonyl, cyano,... 

Two-Group C-C Disconnections III 1,5-Difunctionalised Compounds Conjugate (Michael) Addition and Robinson Annelation... 

Predict the product that would be formed in these conjugate 9. Suggest ways to make these compounds using conjugate addi-additions, tion of enol(ate)s. 

Free sulfilimines are known to undergo conjugate-type addition to electrophilic alkenes to afford aziridines and enamines "1 -1,3. A useful method for the preparation of 16,17starting materials for the synthesis of various compounds with a wide spectrum of physiological activity114, involves the addition of free sulfilimines to ,fi-unsatu-rated oxosteroids. Thus, S,S-diphenylsulfilimine 35 reacts with steroidal cnones (e.g., 34 and... 

Oxazoles 1, benzoxazoles 2, oxazolium salts 3, and oxazole A -oxides 4 are fully conjugated compounds (Figure 1). In addition, the two mesoionic structures l,3-oxazolium-5-olates 5 and (l,3-oxazolium-4-olates) 6, commonly known as miinchnones and isomiinchnones, respectively, are also considered to be conjugated rings. There are five systems of hydroxyl-substituted oxazoles and they exist in their oxo forms the 2(3H)-, 2(5H)-, 4(5//)-, 5(2//)-, 5(4//)-oxazolones 7-11. Three forms of dihydrooxazoles are known 2,3-, 2,5-, and 4,5-dihydrooxazoles respectively 12-14. The fully saturated ring is called oxazoline 15. The monooxo derivatives are 2-oxazolidinone 16,4-oxazolidinone 17, and 5-oxazolidinone 18. The three variants of oxazolidinediones are 19-21 and the fully oxidized oxazolidi-netrione is 22. 

In many of these cases, both the enolate anion and substrate can exist as (Z) or (E) isomers. With enolates derived from ketones or carboxylic esters. The (E) enolates gave the syn pair of enantiomers (p. 166), while (Z) enolates gave the anti pair. Nitro compounds add to conjugated ketones in the presence of a dipeptide and a piperazine. ° Malonate derivatives also add to conjugated ketones, and keto esters add to conjugated esters.Addition of chiral additives to the reaction, such as metal-salen complexes,proline derivatives, or (—)-sparteine, ... 

Sera, A. Addition reactions to conjugated compounds. Org. Synth. High Pressures 1991,179-200. 

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