Iridium Complexes in Olefination Reactions

Abstract

Iridium complexes were found to catalyze the olefination of aldehydes in the presence of triphenylphosphine with both ethyl diazoacetate and trimethylsilyldiazomethane. Conjugated esters were obtained under mild reaction conditions at room temperature using [IrCl(cod)]2, whereas Vaska’s complex was used to synthesize terminal alkenes from trimethylsilyldiazomethane.

Diazo Reagents in Copper(I)‐Catalyzed Olefination of Aldehydes

“…The yield also decreased when running a more diluted or more concentrated reaction (entries [8][9][10]. The reaction can be performed in numerous solvents, but none of them gave better results than THF (entries 12-21).…”

“…Aromatic ethers, substituted anilines, nitro compounds, bromides, esters and aliphatic secondary amines were tolerated under these reaction conditions (entries 1-9). Furthermore, thiophene-, furan-, pyridine-, protected pyrrole-and indole-substituted carboxaldehydes were converted to the corresponding conjugated esters in good to excellent yields (entries [10][11][12][13][14][15]. Clearly the efficiency of the copper catalyst is not affected by these functional groups.…”

“…Overall the copper-catalyzed methylenation reaction exhibits a better functional group compatibility, particularly with nitrogen-containing substrates. A number of transition metal complexes derived from Mo, [5] Re, [6] Fe, [7] Ru, [8] Co [9] and Ir [10] are known to catalyze the olefination of carbonyl compounds [11] with diazo carbonyl reagents, in most cases, diazoacetate derivatives. Not only the use of a cost-effective catalyst, such as a copper(I) salt, would be beneficial, but also the use of other diazo reagents would be highly desirable to further expand the scope of these synthetic methods.…”

Stereospecific Benzyne‐Induced Olefination from β‐Amino Alcohols and Its Application to the Total Synthesis of (−)‐1‐Deoxy‐D‐fructose

“…[1] The outcomes benefit synthetic and natural product chemistry to a great extent. Herein, we contribute a new method to form the C=C bond that is complementary to existing methods.…”

“…Herein, we contribute a new method to form the C=C bond that is complementary to existing methods. Some of the prominent methods include the coupling of aldehydes with organic phosphonium halides in the Wittig reaction, [2] the coupling of two aldehydes in the McMurry reaction, [3] the decomposition of cyclic thionocarbonates in the CoreyWinter reaction, [4,5] the decomposition of cyclic 2-alkoxy-1,3-dioxolanes in the Eastwood olefination, [5] the deoxygenation of epoxides, [1] and so forth. Alternatively, the C=C bond can be generated by 1,2-elimination reactions of substrates containing various functional groups.…”