Electron-donating groups reaction

The phenylacetic acid derivative 469 is produced by the carbonylation of the aromatic aldehyde 468 having electron-donating groups[jl26]. The reaction proceeds at 110 C under 50-100 atm of CO with the catalytic system Pd-Ph3P-HCl. The reaction is explained by the successive dicarbonylation of the benzylic chlorides 470 and 471 formed in situ by the addition of HCl to aldehyde to form the malonate 472, followed by decarboxylation. As supporting evidence, mandelic acid is converted into phenylacetic acid under the same reaction conditions[327]. 

Reaction 12, the acid-catalyzed hydrolysis of substituted benzamides, has p = — 0.22, so the reaction is modestly facilitated by electron-donating groups. This suggests that protonation of the amide is kinetically important ... 

The electronic properties of the aniline are important in the Doebner reaction. The reaction works best with electronic donating groups. Anilines substituted with a chlorine at the meta position consistently give low yields, but fluorine at the meta position seems... 

As previously described, the Gould-Jacobs reaction has been applied to heterocycles fused to anilines, and to some amino-substituted heterocycles. Selectivity of N- and C-cyclization of 2-aminopyridino-methylene malonates has been mentioned (51 and 56). The normal mode of cyclization of 2-aminopyridino-methylene malonates is on the nitrogen to form a pyridopyrimidine. If an electron-donating group (EDG) is in the 6-... 

A number of Lewis acids have been utilized in the Pomeranz-Fritsch reaction, including polyphosphoric acid and boron trifluoride-trifluoroacetic anhydride. Under the latter conditions yields were best when electron-donating groups were present in the 3- or 3, 4- position of imine 20, whereas unactivated aldehydes failed to cyclise at all. ... 

The [ 2 + 4]-cycloaddition reaction of aldehydes and ketones with 1,3-dienes is a well-established synthetic procedure for the preparation of dihydropyrans which are attractive substrates for the synthesis of carbohydrates and other natural products [2]. Carbonyl compounds are usually of limited reactivity in cycloaddition reactions with dienes, because only electron-deficient carbonyl groups, as in glyoxy-lates, chloral, ketomalonate, 1,2,3-triketones, and related compounds, react with dienes which have electron-donating groups. The use of Lewis acids as catalysts for cycloaddition reactions of carbonyl compounds has, however, led to a new era for this class of reactions in synthetic organic chemistry. In particular, the application of chiral Lewis acid catalysts has provided new opportunities for enantioselec-tive cycloadditions of carbonyl compounds. 

Due to the two electron-donating groups in the bicyclic product 150 and the unhydrolyzed precursor of 148, they should be quite reactive dienes in Diels-Alder reactions. However, such [4+2] cycloadditions were observed only for the cyclohexane-annelated cyclopentadienes 151b, which equilibrate with the more reactive isomers 154 by 1,5-hydrogen shifts (Scheme 33). The [4+2] cycload-... 

The best known of metal carbene reactions, cydopropanation reactions, have been used since the earliest days of diazo chemistry for addition reactions to the carbon-carbon double bond. Electron-donating groups (EDG) on the carbon-carbon double bond facilitate this catalytic reaction [37], whereas electron-withdrawing groups (EWG) inhibit addition while facilitating noncatalytic dipolar cycloaddition of the diazo compound [39] (Scheme 5). There are several reviews that describe the earlier synthetic approaches [1, 2,4, 5,40-43], and these will not be duplicated here. Focus will be given in this review to control of stereoselectivity. 

Electron-donating groups strongly activate sulfonylation at ortho or para positions, with para sulfonylation more favored due to less steric hindrance. Variables, such as highly reactive monomers, elevated reaction temperatures, and high... 

Electron-donating groups, effect on thiazolium ring cleavage, 33 Electrophilic reaction, of thiazolium salts, in basic medium, 34 Energetic transfer yield, of thiazoiocyanines, 78... 

---