With carbonyl group compounds

The reaction that prevails when the reaction is under kinetic control is the one that is faster. Therefore, the product depends on the reactivity of the carbonyl group. Compounds with reactive carbonyl groups form primarily direct addition products because for those compounds, direct addition is faster. Compounds with less reactive carbonyl groups form conjugate addition products because for those compounds, conjugate addition is faster. 

Synthetically useful stereoselective reductions have been possible with cyclic carbonyl compounds of rigid conformation. Reduction of substituted cyclohexanone and cyclopentan-one rings by hydrides of moderate activity, e.g. NaBH (J.-L. Luche, 1978), leads to alcohols via hydride addition to the less hindered side of the carbonyl group. Hydrides with bulky substituents 3IQ especially useful for such regio- and stereoselective reductions, e.g. lithium hydrotri-t-butoxyaluminate (C.H. Kuo, 1968) and lithium or potassium tri-sec-butylhydro-borates or hydrotri-sec-isoamylborates (=L-, K-, LS- and KS-Selectrides ) (H.C. Brown, 1972 B C.A. Brown, 1973 S. Krishnamurthy, 1976). 

If the substituent R4 is not conjugated with the carbonyl group (compounds (377) in Scheme 3.215), silylation proceeds in a different fashion (153, 292, 470). After the formation of the initial SENAs (378), the latter undergo reversible cyclization to give cyclic iminium cations B, which are stabilized by deprotonation of the C-4 atom to form the cyclic intermediates 2// -5,6-dihydrooxazines C. 

Transformation of both the ester and nitrile derivatives 726 or 727 into pyrano[2,3-t7 pyridazines 728 or 729, respectively, by treatment with dilute HCl at room temperature involved nucleophilic displacement of the morpholine group by the hydroxyl group with an acidic hydrolysis followed by intramolecular iminolactonization and then hydrolysis of the formed imino group to a carbonyl group. Compounds 726 and 727 were prepared by Vilsmeier-Haack formylation of 2-methyl-5-morpholino-3(2/7)-pyridazinone 724 followed by condensation of the resulting product 725 with either ethyl a-cyanoacetate or malononitrile in EtOH (Scheme 34) <1994H(37)171>. 

For the acyclic derivatives prior to reaction, the favored conformation of the C-l-C-2 rotamers would have the carbonyl group eclipsed with the hydrogen atom on C-2 (111), and, consequently, the favored side of attack for ammonia would be the same side as that of the acyl group on 0-2, to give 112 as the preponderant orientation for the initial addition-compound. Thereafter, migrations from the chain take place. This migration would be limited by the necessity of an ade-... 

By Reduction of Unsaturated Precursors The method of choice for labeling with tritium is the reduction of a suitable unsaturated precursor (containing a double bond, carbonyl group, etc.) with carrier-free tritium gas or tritiated metal hydrides. The major limitation of this method is the availability of a suitable unsaturated precursor of the desired compound. It is essential to carry out the synthesis in a non-hydroxylic solvent (dioxane, ethyl acetate, etc.). Reductions carried out in alcohol or water will lead to almost complete exchange of the tritium gas with the solvent. 

Most compounds studied have a carbonyl group conjugated with the benzene ring and nearly all reactions are intramolecular cycloadditions. In most cases, the alkenyl moiety is connected to the arene ring via an oxygen atom, ortho or para with respect to the carbonyl group. 

In the first part of this one-pot multi-component reaction a carbonyl group reacts with a CH-acidic compound. 

The carbonyl group in such compounds fails to react with carbonyl reagents. When, however, the nitrogen no longer has unshared electrons, as in CCXI, then in spite of the close spatial relation, the carbonyl group reacts with hydroxylamine to form an oxime (98). 

Both functional groups of a, 3-unsaturated carbonyl compounds have Jt bonds, but individually, they react with very different kinds of reagents. Carbon-carbon double bonds react with electrophiles (Chapter 10) and carbonyl groups react with nucleophiles (Section 20.2). What happens, then, when these two functional groups having opposite reactivity are in close proximity ... 

Even higher multiplicities of specificity combinations are possible. In Scheme 49, conversion of (115) to (116) involves regiospecific reduction of an enantiotopic carbonyl group concurrently with enantiotopic face specificity. This transformation can also be achieved using Saccharomyces species, with the level of (116) produced being enhanced by the addition of unsaturated carbonyl compounds, such as acrolein. ... 

Among the carbon electrophiles, carbonyl compounds [113,114] were first applied in the reaction with lithiated ferrocenylalkyl amines (Sect. 4.S.3.3 and Fig. 4-18). Analogously, carboxylic acids are obtained from CO2 [153]. The reactivity pattern of palladated ferrocenylalkyl amines with carbon electrophiles is somewhat different. Carbon monoxide in alcohols leads to the formation of esters of substituted ferrocenecarboxylic acids [124]. With prochiral alcohols, a moderate asymmetric induction is observed [154]. a, -Unsaturated ketones react with palladated ferrocenylalkyl amines not with addition to the carbonyl group, but with substitution of a hydrogen at the carbon—carbon double bond, allowing the introduction of longer side chains at the ferrocene ring (Fig. 4-27c) [124, 152]. 

Osazones. Glucosazone.— This intermediate product, the oxidation compound, containing, now, a new carbonyl group, reacts with a third molecule of phenyl hydrazine forming a double phenyl hydrazone which is known as an osazone. From glucose the osazone is known as glucosazone. 

The hydrogen atom in the ortho position to the carbonyl group unites with the hydroxyl group of the carboxyl to effect the ring closure. The preparation of o-benzoylbenzoic acid from benzene and phthalic anhydride (Experiment 63) and the dehydration of this keto acid to anthraquinone considered in the present experiment illustrate the building up of polynuclear compounds from simpler benzene derivatives. 

Acetalizjation. The silylated diol is used in the protection of the carbonyl group (dehydration with 3A molecular sieves in dichloromethane). Carbonyl compounds are regenerated from the 5-trimethylsilyl-l,3-dioxanes by treatment with LiBF in refluxing THF. 

The enrichment in nitrogen of humic substances extracted in EDA (Table 5) suggests that solvents containing this compound, or any other primary amine, would not be appropriate for use with humic substances. EDA readily reacts with carbonyl groups to form Schiff base structures. Such reactions are rapid when the protonated carbonyl group reacts with the nonpro-tonated amine. Thus the maximum reaction rate occurs when the product of the concentrations of the protonated carbonyl groups and free amines is maximum. The reaction continues, but at a rate which decreases in an exponential manner, as the pH is raised or lowered from the optimum value for the reaction. 

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