gem-Dibromomethylarenes:  A Convenient Substitute for Noncommercial Aldehydes in the Knoevenagel−Doebner Reaction for the Synthesis of α,β-Unsaturated Carboxylic Acids

Abstract

A facile synthesis of alpha,beta-unsaturated carboxylic acids from gem-dibromomethylarenes is described. gem-Dibromomethylarenes are employed for the first time in the Knoevenagel-Doebner reaction as aldehyde equivalents for the efficient synthesis of alpha,beta-unsaturated carboxylic acids.

β‐Alanine‐DBU: A Highly Efficient Catalytic System for Knoevenagel‐Doebner Reaction under Mild Conditions

“…The piperidine and pyridine, [20,21] efficient organocatalysts for general Knoevenagel-Doebner reactions, showed no catalytic activity at room temperature (Entries 2 and 3, Table 1). For β-alanine, a reported efficient catalyst for the Knoevenagel-Doebner reaction under refluxing condition, [22] only moderate amount of product was produced in EtOH (Entry 4, Table 1).…”

Combined Transition‐Metal‐ and Organocatalysis: An Atom Economic C3 Homologation of Alkenes to Carbonyl and Carboxylic Compounds

“…Two-carbon homologation of aliphatic aldehydes. dinium acetate in dimethyl sulfoxide at 100 8C as described by Ragoussis et al [25,38] …”

General Approach to Anthrapyran Antibiotics Exemplified by the Synthesis of rac‐γ‐Indomycinone

“…Postulated reaction mechanism of the olefination according to Augustine et al [15] www.eurjoc.orghoped that preferential bromination of the ethyl side chain would take place, so that these monobromides could be used in subsequent Wittig reactions to attach missing parts of different side chains such as in rubiflavinone (16) (see Scheme 2). In the first experiment, by using the most soluble n-butanoic ester 12c, a mixture of the monobromide 13c (36 %) and the dibromide 14c (32 %) was isolated.…”