Aldehyde summary

Introduction The extended enolate problem Kinetic and thermodynamic control Wittig and Horner-Wadsworth-Emmons Reactions Extended Aza-Enolates Extended Lithium Enolates of Aldehydes Summary a-Alkylation of Extended Enolates Reaction in the y-Position Extended Enolates from Unsaturated Ketones Diels-Alder Reactions Extended Enolates from Birch Reductions The Baylis-Hillman Reaction The Synthesis of Mniopetal F... 

Summary of Reactions Discussed in Earlier Chapters That Yield Aldehydes and Ketones... 

Summary of Reactions of Aldehydes and Ketones Discussed in Earlier Chapters... 

In summary, the Bucherer-Bergs reaction converts aldehydes or ketones to the corresponding hydantoins. It is often carried out by treating the carbonyl compounds with potassium cyanide and ammonium carbonate in 50% aqueous ethanol. The resulting hydantoins, often of pharmacological importance, may also serve as the intermediates for amino acid synthesis. 

The enantioselectivities of the reactions of representative achiral aldehydes and chiral allylboron reagents arc compared in Table 4. A comparison of the enantioselectivities of the (Z )-2-butenyl reagents appears in Table 5, while Table 6 provides a similar summary of the reactions of the (Z)-2-butenyl and 3-methoxy-2-propcnyl reagents. A 3-diphenylamino-2-propenyl reagent was recently reported102. 

Summary of the Relationship between Diastereoselectivity and the Transition Structure. In this section we considered simple diastereoselection in aldol reactions of ketone enolates. Numerous observations on the reactions of enolates of ketones and related compounds are consistent with the general concept of a chairlike TS.35 These reactions show a consistent E - anti Z - syn relationship. Noncyclic TSs have more variable diastereoselectivity. The prediction or interpretation of the specific ratio of syn and anti product from any given reaction requires assessment of several variables (1) What is the stereochemical composition of the enolate (2) Does the Lewis acid promote tight coordination with both the carbonyl and enolate oxygen atoms and thereby favor a cyclic TS (3) Does the TS have a chairlike conformation (4) Are there additional Lewis base coordination sites in either reactant that can lead to reaction through a chelated TS Another factor comes into play if either the aldehyde or the enolate, or both, are chiral. In that case, facial selectivity becomes an issue and this is considered in Section 2.1.5. 

In summary, the most popular hydrogen donors for the reduction of ketones, aldehydes and imines are alcohols and amines, while cyclic ethers or hydroaromatic compounds are the best choice for the reduction of alkenes and alkynes. 

In summary, the reduction of ketones and aldehydes can both be performed with MPV and transition-metal complexes as catalysts. Reductions of alkenes, al-kynes, and imines require transition-metal catalysts MPV reductions with these substrates are not possible. 

Since the discovery of amino alcohol induced dialkylzinc addition to aldehydes, many new ligands have been developed. It has recently been reported that chiral amino thiols and amino disulfides can form complexes or structurally strained derivatives with diethylzinc more favorably than chiral amino alcohols and thus enhance the asymmetric induction. Table 2 15 is a brief summary of such chiral catalysts. 

In summary the concentration of ozone in the polluted atmosphere is controlled by the intensity of sunlight and the ratio of nitrogen dioxide to nitric oxide. Hydrocarbons and other pollutants—such as aldehydes, ketones, chlorinated hydrocarbons, and carbon monoxide—react to form peroxy radicals. These, in turn, react with nitric oxide, causing the ratio [NOjjilNO] to increase. As a consequence of Equation 2-5, the ozone concentration also increases. 

Scheme 1. Am1de/Blocked Aldehyde Reaction Summary...

In summary, gas-phase reactions between aldehydes and NOj occur readily and with strong exothermicity. The rate of reaction is largely dependent on the alde-hyde/N02 mixture ratio, and is increased with increasing NO2 concentration for aldehyde-rich mixtures. On the other hand, no appreciable gas-phase reactions involving NO are likely to occur below 1200 K. The overall chemical reaction involving NO appears to be third order, which impUes that it is sensitive to pressure. The reactions discussed above are important in understanding the gas-phase reaction mechanisms of nitropolymer propellants. 

In summary, the differences between Br0nsted-acid catalysis and hydrogen-bond catalysis were discussed. Because there is a gradual transition from hydro-gen-bond catalysis to Bronsted-acid catalysis, it is not always easy to differentiate the two modes of catalysis. However, the combination of a stronger acid and an imine will be a Bronsted-acid-catalyzed reachon, while the combination of a neutral acid and an aldehyde will be a hydrogen-bond-catalyzed reaction. 

Five- and Six-Membered Ring Heterocycles with One, Two, or Three Sulfur Atoms. A summary of the various sulfur heterocycles formed from aldehydes in the presence of hydrogen sulfide and the corresponding analytical data are presented in Table I. Examples of aldehydes used in this reaction include propionaldehyde, butyraldehyde and caproaldehyde. 

SUMMARY OF ALDEHYDE CHEMISTRY PREPARATION 1. Aliphatic Aldehydes... 

The down-regulated proteins in HCC tissues have been identified. Park et al. identified aldehyde dehydrogenase 2 (25) and ferritin light chain (32). Kim et al. identified HSP 27, cathepsin D, and others (26). Lim et al. identified cytochrome B5, liver car-boxyesterase, and others (27). Li et al. identified SOD 1, aldolase B, and others (28). Fujii et al. identified galectin-1 (29). Kim et al. identified argininosuccinate synthase, carbamoyl-phosphate s mthase, and others (31). Table 1 shows the summary of the proteins whose expression was different between HCC cancer tissues and non-cancerous tissues. 

A chapter written in 1996 covers hydroformylation catalyzed by organometallic complexes in detail,219 whereas a review written 5 years later gives a summary of the advances on hydroformylation with respect to synthetic applications.220 A selection of papers in a special journal issue has been devoted to carbonylation reactions.221 A major area of the research has been the development of fluorous biphasic catalysis and the design of new catalysts for aqueous/organic biphasic catalysis to achieve high activity and regioselectivity of linear or branched aldehyde formation. 

Table 2 lists 37 sialic acid derivatives and analogues that have been synthesized with sialic acid aldolase by our group and others. This is a nice illustration of the great synthetic potential of the enzyme. In all of these examples, sialic acid derivatives or analogues with equatorial hydroxyl on C-4 are formed, corresponding to a new 45 chiral center and attack of the pyruvate from the si face of the aldehyde. In summary sialic acid aldolase accepts modifications on the 2, 4, 5, and 6 positions of the substrate without any change of its stereoselectivity. 

Table Gl.5.9 is a summary of the total available oil for various citrus cultivars. Table G1.5.10 is the aldehyde composition for orange and grapefruit oils.

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