Addition reactions to carbonyl

Azirine, trans-2-methyl-3-phenyl-racemization, 7, 33, 34 1-Azirine, 2-phenyl-reactions, 7, 69 with carbon disulfide, S, 153 1-Azirine, 3-vinyl-rearrangements, 7, 67 Azirines, 7, 47-93 cycloaddition reactions, 7, 26 fused ring derivatives, 7, 47-93 imidazole synthesis from, 5, 487-488 photochemical addition reactions to carbonyl compounds, 7, 56 photolysis, 5, 780, 7, 28 protonated... 

A number of groups have criticized the ideas of Dauben and Noyce, especially the concept of PDC. Kamernitzsky and Akhrem, " in a thorough survey of the stereochemistry of addition reactions to carbonyl groups, accepted the existence of SAC but not of PDC. They point out that the reactions involve low energies of activation (10-13 kcal/mole) and suggest that differences in stereochemistry involve differences in entropies of activation. The effect favoring the equatorial alcohols is attributed to an electrostatic or polar factor (see also ref. 189) which may be determined by a difference in the electrostatic fields on the upper and lower sides of the carbonyl double bond, connected, for example, with the uncompensated dipole moments of the C—H bonds. The way this polar effect is supposed to influence the attack of the hydride is not made clear. 

We have intentionally selected example reactions (Figs. 29-33) that would not usually be immediately obvious to a chemist. The examples chosen have all been concerned with rearrangements of various types, since their courses are frequently difficult to predict. It remains to emphasize that the reactivity functions contained in EROS perform perfectly well with other types of reaction. This is true, for example, with reactions that a chemist could derive directly from an analysis of the functional groups in a molecule. Thus, EROS predicts addition reactions to carbonyl compounds, nucleophilic substitutions, and condensation reactions, to name just a few examples. In all these reaction types, the possibility of assigning a quantitative estimate to the reactivity at the various sites via the reactivity functions is of particular merit. It... 

The balance between anion activation and cation inhibition of addition reactions to carbonyl groups is exemplified by the reaction of acetonitrile anion with benzaldehyde (Scheme 7). When the cation is Li+, addition of [2.1.1]cryptand (15b) markedly decreases the reaction rate suggesting cation inhibition is dominant. When M = K+, addition of [2.2.2]cryptand (15d) increases the rate by, presumably, a predominant anion activation. Finally when M = Na+, the two effects cancel out and the reaction rate is unaffected by [2.2.1]cryptand (15c) addition (80PAC2303,81TL1685). 

Acetalization (see Addition reactions to carbonyl groups, Protection of aldehydes and ketones)... 

N-Phenylselenophthalimide, 245 Additions involving selenium Benzeneselenenyl halides, 26 N-Phenylselenophthalimide, 245 Miscellaneous reagents Aluminum chloride, 15 Lithium bis(dimethylphenyl-silyl)cuprate, 161 Organotin reagents, 211 Addition reactions to carbonyl... 

Magnesium, 235 Samarium(II) iodide, 270 Titanium(IV) chloride, 304 Addition reactions to carbonyl groups—Addition of functionalized CARBON NUCLEOPHILES (see also Aldol reaction and other specific condensation reactions, Meth-ylenation, Peterson Olefination, Refor-matsky reaction, Wittig reaction, Wittig-Horner reaction)... 

Aluminum chloride, 15 Arenediazonium tetrafluoroborates, 19 Rhodium(II) carboxylates, 266 Tris(dimethylamino)sulfonium difluoro-trimethylsilicate, 336 Asymmetric reactions Addition reactions to carbonyl groups Bis(2,4-dimethyl-3-pentyl) tartrate, 36 (S)-( + )-2-Methoxymethylpyrrolidine, 180... 

Addition and Conjugate Addition Reactions to Carbonyl Compounds... 

The equilibrium position of addition reactions to carbonyl compounds is also influenced by electronic substituent effects, as was also shown in Figure 9.1 ... 

In our present discussions, 1,2- and 1,4-additions to carbonyl systems were introduced. However, these reactions were not presented in the context of specific carbonyl-based functional groups. Expanding upon this concept, the three types of functional groups generally used in addition reactions to carbonyls are aldehydes, ketones, and esters. 

Organogallium compounds are good nucleophiles for performing addition reactions to carbonyl functionalities. Alkylation, allylation, aldol condensation, and the Reformatsky reaction proceed readily with organogallium reagents. 

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