Conjugate allylation

CONJUGATE ALLYLATION OF a. -UNSATURATED KETONES WITH ALLYLSILANES 4-PHENYL-6-HEPTEH-2-0NE (6-Hepten-2-one, 4-pheny1-)... 

CONJUGATE ALLYLATION OF a,g-ENONES WITH ALLYLSILANES PROMOTED BY TITANIUM TETRACHLORIDE Conditions... 

Intramolecular conjugate allylation (12, 25).2 Fluoride ion catalyzes intramolecular Michael additions of allyltrimethylsilane to a,p-enones as well as a,p-unsaturated esters, nitriles, and amides Lewis acid catalysis is not effective. The method is particularly suited to cyclopentane annelations.2... 

Conjugate allylation with allyisUanes. This Lewis acid allows conjugate addition of allylsilanes to enones with regiospecific transposition of the allyl group. Acyclic and cyclic enones and even fused cyclic enones react satisfactorily.1 Examples ... 

Conjugate allylation reactions, characteristics, 9, 312 Conjugated alkenes, with Pd n-complexes, 8, 334 Conjugated dienes via Pd(IV) catalysts, 8, 306 polymerization, 4, 1084... 

Conjugated dienes are needed for the Diels-Alder reaction (chapter 17) and Wittig disconnection 61 reveals that the choices here are more important. The easily prepared enals 62 would react with an unstabilised ylid 63 to give a Z-alkene but the conjugated allylic ylid 60 might give the -alkene. 

Compared with the direct allylation of carbonyl groups, little has been reported on the selective conjugate allylation of enones. Allylic tantalum species, generated by the Sn-Ta exchange, is the choice of tools for performing conjugate addition of sterically hindered allylic groups (Equation (43)).140... 

Note that in 9.33 hydride abstraction generates quaternary nitrogen containing conjugated allyl amine ligand. This prochiral molecule coordinates to the... 

On the basis of these findings, a combination of this intramolecular crosscoupling with an initial intermolecular Michael addition was reported by Singer in order to afford cyanobenzofulvene acetal 85 which was an intermediate of the synthesis of a benzazepine [81]. Thus, Michael addition of 2-halophenylacetonitrile derivatives of 86 to ethoxy acrylate performed in the presence of a large excess of base leads to the corresponding conjugated allylic anion 87. The crucial issue in this process is the oxidative addition of the palladium to the electron-rich arene. This problem was solved... 

We have already drawn resonance structures for the acetate anion (Section 2.5C) and the aUyl radical (Section 15.10). The conjugated allyl carbocation is another example of a species for which two resonance structures can be drawn. Drawing resonance structures for the allyl carbocation is a way to use Lewis stmctures to illustrate how conjugation delocalizes electrons. 

LPDE solution also catalyzes the conjugate allylation of quinones. This is an important reaction in the preparation of biologically active isoprenoid quinones such as vitamin E, vitamin K, coenzyme Qi, and plastoquinones. If 123 is reacted with the allylsi-lane in 5.0 m LPDE for 15 h at 40 °C, allylhydroquinone 124 is obtained in 73 % yield, together with non-allylated hydroquinone 125 (Sch. 63) [113]. 

The most recent developments in the synthesis and reactivity of isolated Si=E bonds (X = P, As) in 2, 4, and 6 will be the main focus in this paper. Furthermore, we discuss the synthesis and reactivity of the first l,3-disila-2-phosphaallylfluoride derivative, that is, a silylidenephosphane bearing a potentially conjugated allylic Si2P-7t system [18],... 

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