Triphosgen, ein kristalliner Phosgen‐Ersatz

Abstract

Thermisch stabil, wenig flüchtig, einfach zu transportieren und zu lagern, exakt dosierbar – das sind die Vorteile von Kohlensäure‐bis(trichlormethylester) 1 als Phosgen‐Ersatz. Darüber hinaus genügen stöchiometrische Mengen 1 für Chlorformylierungen, Carbonylierungen, Chlorierungen und Dehydratisierungen, die obendrein mit guten bis sehr guten Ausbeuten verlaufen.magnified image

Efficient Amide Bond Formation through a Rapid and Strong Activation of Carboxylic Acids in a Microflow Reactor

“…We speculated that the phosgene, generated in situ by the reaction between the base and triphosgene, converted the carboxylic acid into the corresponding acid chloride. [6,3n, w] We anticipated that the epimerization was suppressed by reducing the residence time of the highly electrophilic active species to less than one second. To accomplish amidation, a solution of the amine in solvent C was then introduced into the second mixer with a syringe pump.…”

The Four‐Component Reaction and Other Multicomponent Reactions of the Isocyanides

“…Later, when phosgene transportation was not allowed anymore, it was locally produced from triphosgene. 32 Also diphosgene 33 and phosphorus oxychloride, 4 can be used, particularly in the presence of di-isopropylamine. 34 Baldwin et al 35 prepared naturally occurring epoxy-isocyanides from the corresponding formylamines by dehydrating the latter with trifluoromethyl sulfonic acid anhydride in the presence of di-isopropylamine.…”

Efficient Amide Bond Formation through a Rapid and Strong Activation of Carboxylic Acids in a Microflow Reactor

“…Various carboxylic acids, which included easily racemizable amino acids, were activated using an inexpensive and less-toxic solid triphosgene, [6] and the racemization was suppressed ( 3 %) by reducing the residence time of the highly active species [1] (0.5 s) through microflow synthesis. [7] The active species rapidly reacted (4.3 s) with less nucleophilic amines, including N-methyl amino acids, in good to excellent yields at ambient temperature (20 8C).…”

“…Initially, solvents were examined as shown in Table 1 (entries [1][2][3][4][5][6][7][8][9][10]. N-Boc-O-benzyl-l-serine (1) and l-phenylalanine allyl ester (2) were employed as substrates since they have bulky side chains at the a-position.…”

“…A decreased yield (74 %) with a substantial generation of the epimer (18 %) was observed by employing the batch conditions (entry 5). Less-nucleophilic bulky amines such as l-isoleucine, l-proline, and sarcosine were coupled with lserine in good yields (89, 80, and 74 %, respectively) without detectable epimerization (entries [6][7][8]. The corresponding batch reactions resulted in a reduction in yields (47, 58 and 53 %, respectively).…”