Diazoketones, aromatic, from acid

DIAZOCYCLOHEXANONE, 51, 86 a-Diazoketones, reaction with trialkylborane, 53, 82 rearrangement, 52, 53 synthesis, 52, 53 >°-Diazoketones, aromatic, from acid chlorides, 53, 37 -Diazoketones, cyclic, alkylation of, 53, 82, 83 Diazomethane, in modified Arndt-... 

One of the most common approaches to pyrazine ring construction is the condensation of diaminoethane and 1,2-dicarbonyI compounds such as 206 to provide pyrazines 207 after aromatization. Aromatization was accomplished by treating the dihydropyrazines with manganese dioxide in the presence of potassium hydroxide <00JCS(P1)381>. The N-protected 1,2-dicarbonyl compounds 206 were prepared from L-amino acids by initial conversion into diazoketones followed by oxidation to the glyoxal. 

Acid chlorides, reduction to aldehydes, 53, 55 Acid chlorides, aromatic, diazoketones from, 53, 37... 

Carbenes and carbenoids constitute a class of reactive intermediates traditionally intimately associated with the synthesis of cyclopropanes, and more recently with products derived from C-H insertion processes. The reactions of diazoacetic acid esters with aromatic hydrocarbons such as toluene to give cyclopropanes with the liberation of N2, date back to the seminal experiments by Buchner and Curtius reported in 1885 [11]. Much later, in 1942, Meerwein reported that carbenes generated from diazomethane undergo insertion into C-H bonds [12], Seminal experiments that had significant impact for the utilization of such reactions in synthesis were performed by Stork, who demonstrated that carbenes prepared by photolysis of diazoketones participated in stereospecific intramolecular cycloadditions with al-kenes to form bicyclic cyclopropanes (Equations 1 and 2) [13]. Julia reported that intramolecular C-H insertion reactions of a chiral substrate 5 including a stereogenic methine center proceeded stereospecifically with retention of configuration (Equation 3) [14]. 

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