Imines carbonyl

Among the catalytic asymmetric alkyne additions to the sp carbon center, such as carbonyl, imines, and iminiums, truly metal-catalyzed alkyne addition to alkenes is rare. By using a PINAP derivative (Figure 5.4), Cu-catalyzed Michael addition... 

Carbonyl imines (43) Azomethine imines (44) Thiocarbonyl imines... 

This list shows that the five-membered meso-ionic heterocycles related to the azomethine imine 1,3-dipole (43) comprise the largest group and that meso-ionic compounds related to the nitrosoimines (39), thionitrosoimines (41), and carbonyl imines (42) are not yet known. Clearly synthetic challenges still exist in the field of meso-ionic compounds. 

Compounds with a low HOMO and LUMO (Figure 5.5b) tend to be stable to selfreaction but are chemically reactive as Lewis acids and electrophiles. The lower the LUMO, the more reactive. Carbocations, with LUMO near a, are the most powerful acids and electrophiles, followed by boranes and some metal cations. Where the LUMO is the a of an H—X bond, the compound will be a Lowry-Bronsted acid (proton donor). A Lowry-Bronsted acid is a special case of a Lewis acid. Where the LUMO is the cr of a C—X bond, the compound will tend to be subject to nucleophilic substitution. Alkyl halides and other carbon compounds with good leaving groups are examples of this group. Where the LUMO is the n of a C=X bond, the compound will tend to be subject to nucleophilic addition. Carbonyls, imines, and nitriles exemplify this group. 

Unmasking of carbonyl, imine R formation, iminc-cnaminc tauiomerization... 

Rs Inline ylide 8 Carbonyl ylide 9 R4 10 Carbonyl imine... 

Numerous dinucleating macrocyclic and macrobicyclic ligands have been synthesized, in particular by the versatile amine + carbonyl — imine reaction they form dinuclear metal complexes as well as cascade complexes with bridging groups [2.58-2.63, 3.24-3.27, 4.1-4.4], for instance in dicobalt complexes that are oxygen carriers [3.26]. 

In the presence of Mn(OAc)3 or a Ce(iv) salt, 1,3-dicarbonyl compounds and /3-carbonyl imines react with allylsilanes to give silylmethylated dihydrofurans and dihydropyrroles, respectively.199,200,20011 A proposed mechanism involves the formation of a /3-silylcarbenium ion intermediate via two-electron oxidation and subsequent intramolecular nucleophilic attack (Equation (51)). a... 

All the functional groups described in Section 2.1.1.6.2.2.1. (carbonyl, imines. etc.) can react as part of a heterodiene when they are adjacent to a.j)-unsaturation, and cycloadditions lead to the analogous hclerocyclic compounds. 

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