Creation of Novel Toxic Gas Surrogates and the Development of Safe and Facile Catalytic Reactions

Abstract

The use of toxic gas surrogates in organic reactions instead of the gas itself contributes to enhancing the safety, practicality, and efficiency of the reactions involved. Our efforts toward the creation of toxic gas surrogates and the development of a series of catalytic reactions using these surrogates are described. Improvements in substrate scope during the hydroesterification of alkenes using formates facilitated by the Ru-imidazole catalyst system provided the opportunity to discover that phenyl formate is a useful carbon monoxide (CO) surrogate for the generation of CO and phenol under weakly basic conditions. This discovery triggered the development of highly reactive but stable CO surrogates and a variety of Pd-catalyzed carbonylative transformations. N-Formylsaccharin facilitated the use of additional nucleophiles in carbonylation reactions that provided access to a variety of carbonyl compounds. Detailed experimental and theoretical mechanistic studies into the generation of CO from phenyl formate suggest that CO generation proceeds via a concerted E2 α-elimination. Furthermore, a known surrogate of sulfur dioxide was applied for the first time to the selective syntheses of cyclic sulfonamides and sulfinamides, confirming that the surrogate operates as an "S O" source. Notably, the reactions described herein are scalable and can be performed without the use of external toxic gases and specialized reaction vessels; they are easy and simple to perform and demonstrate enormous potential for industrial application.

In Silico Investigation of Ligand-Regulated Palladium-Catalyzed Formic Acid Dehydrative Decomposition under Acidic Conditions

“…Carbonylation reactions constitute a potent tool to manufacture carboxylic acids and their derivatives in both the industry and academic organic synthesis. − In general, the proceeding of carbonylation requires the use of toxic carbon monoxide, which thus usually requires certified high-pressure reaction vessels . Therefore, developing nongaseous CO surrogates for conducting safe and facile-operation carbonylation with a stoichiometric amount of CO in common Pyrex glass vessels (e.g., two-chamber reactor and sealed glass tube) is an important and ongoing research topic in the realm of homogeneous catalysis. − Among these established CO surrogates, formic acid and its derivatives constitute one kind of versatile atom-economic C1 source. Different from the decomposition of formic ester or N -formyl imides releasing CO in the basic conditions for the carbonylation of aryl or alkyl halides, − the dehydrative decomposition of HCOOH to CO generally depends on the Morgan reaction using excess strong mineral acid (e.g., excess high-concentration sulfuric acid), which is incompatible with the conditions for most of the transition-metal catalyzed carbonylation reactions.…”

Acyl Fluorides in Late‐Transition‐Metal Catalysis

“…In 2013, Konishi, Manabe,a nd Ueda reported ap alladium-catalyzed fluorocarbonylation of aryl bromides using N-formylsaccharin and KF. [54] It is noteworthy that this reaction employed crystalline N-formylsaccharin as the CO source,w hich avoids the use of toxic gaseous CO (Scheme 10).…”

Carbonsäurefluoride in der Katalyse durch späte Übergangsmetalle

“…2013 beschrieben Konishi, Manabe und Ueda eine Palladium-katalysierte Fluorcarbonylierung von Arylbromiden zu Carbonsäurefluoriden mittels N-Formylsaccharin und KF. [54] Bemerkenswert ist, dass bei der Reaktion kristallines N-Formylsaccharin als CO-Quelle verwendet wurde,w odurch auf die Verwendung von giftigem, gasfçrmigem CO während der Fluorcarbonylierung verzichtet werden konnte (Schema 10). Carbonsäurechloriden in Säurefluoride bei Raumtemperatur fungieren kann (Schema 11).…”