Facile synthesis of 2-azaazulenes from thiobenzoyl isocyanates using trimethylsilyldiazomethane

Improved Arndt−Eistert Synthesis of α-Diazoketones Requiring Minimal Diazomethane in the Presence of Calcium Oxide as Acid Scavenger

“…However, this methodology presents the drawback of its limited applicability to aromatic carboxylic acids. Analogously, the more expensive trimethylsilyldiazomethane (TMSCHN 2 ) − has been used as a substitute of diazomethane in Arndt−Eistert reactions, but prior activation of the carboxylic acid as a mixed anhydride is often required when amino acids are used as substrates . In addition, when the acid is activated by reaction with DCC, an equimolar ratio of diazoketone and trimethylsilylmethyl ester is obtained, thus lowering the chemoselectivity of the process.…”