First Synthesis of Highly Chemiluminescent Benzo[b]furan‐2(3H)‐ones Bearing a Urea Substructure

Abstract

A series of benzo[b]furan‐2(3H)‐ones (coumaran‐2‐ones) bearing a urea substructure, namely derivatives of 3‐(aminocarbonylamino)benzo[b]furan‐2(3H)‐one, was prepared for the first time. The accessibility of these compounds through an electrophilic α‐amidoalkylation approach of phenols (Tscherniac–Einhorn reaction) in the key step as well as the chemiluminescence (CL) properties of the desired compounds are strongly dependent on the substitution patterns at the urea moiety. Competing reaction pathways are discussed and an improved one pot synthetical approach of also general interest is presented. In conclusion, especially N,N‐dialkylaminocarbonylamino‐derivatives of benzo[b]furan‐2(3H)‐ones exhibit a strong flash like blue CL upon treatment with bases such as 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) in the presence of oxygen or hydrogen peroxide. Comparative physico‐chemical investigations revealed that novel compounds outperform their urethane‐analogues in terms of CL‐intensity and the speed of the decay making them potentially useful as new tools for CL‐based applications on the short time scale.

Synthesis of Diaminoacetic Acid Derivatives as a Promising Scaffold for the Synthesis of Polyheterocyclic Cage Compounds

“…The literature overview demonstrates that a staple method for the derivatization of diaminoacetic acid is the acid-catalyzed condensation between glyoxylic acid or its esters with carboxamides or substituted sulfonamides. The process is run in aqueous medium, , chlorophorm, toluene, − benzene, acetone, ,, or xylene . Mixed phosphoric/sulfamic acids, 2-naphthalenesulfonic acid , or p-toluenesulfonic acid, ,, are used as the acid catalysts.…”

“…The condensation between the selected amides and ethyl glyoxylate or glyoxylic acid to furnish 2 was explored herein in chloroform, benzene, acetone, toluene, or xylene at reflux, as well as in aqueous medium at room temperature. The selected solvents are most often utilized in this process. − The starting compounds were used in stoichiometric quantities. In all experiments, the resulting water was removed by a Dean–Stark trap to shift the reaction toward the condensation products (the Le Chatelier–Brown principle).…”

5-Chlorocoumaranone-Conjugates as Chemiluminescent Protecting Groups (CLPG) and Precursors to Fluorescent Protecting Groups (FPG)

“…The fine structure is designated using the following abbreviations: s Scheme 1. Structures of the parent benzofuran-2(3H)-one (1a), 5-chloro-coumaranone with a carbamate-linker (1b) published by Lofthouse et al [22], and 5-fluoro-coumaranone with a urea-linker (1c) described by Krieg et al [23].…”

“…Synthesis of methyl ((5-chloro-2-oxo-2,3-dihydrobenzofuran-3-yl)carbamoyl)-(S) -phenylalaninate (5E): The synthetic protocol of Krieg et al [23] was followed with small variations: (S)-methyl 3-phenyl-2-ureidopropanoate 3 (1.0 g, 4.50 mmol, 1.0 eq.) and glyoxylic acid monohydrate (0.41 g, 4.50 mmol, 1.0 eq.)…”

“…The syntheses of the urea-and carbamate-containing precursors were performed a cording to the synthesis protocols of Chegaev et al [29], Nicolas et al [30] and Graf [31 respectively. The two urea compounds 2 and 3 were obtained in quantitative yields, th carbamates of paracetamol 4 and L-menthol 7 with yields of 72% and 88%, respectivel The coumaranones with a urea substructure 5A and 5E were synthesized according to th procedure by Krieg et al [23] (Scheme 2). Instead of stirring the solutions at room tempe ature for one or several days, the process was accelerated by refluxing the reaction mixtu for 4-8 h. Longer periods of refluxing led to a decrease in yield and resulted in the almo complete hydrolysis of the esters.…”