The methoxycarbonylation of aryl chlorides catalysed by palladium complexes of bis(di-tert-butylphosphinomethyl)benzene

Abstract

A catalyst system based on palladium-1,2-bis-(di-tert-butylphosphinomethyl)benzene (BDTBPMB) shows good activity for the methoxycarbonylation of strongly activated aryl chlorides, like 4-chloromethylbenzoate or 4-chlorocyanobenzene. Surprisingly, the use of less activated aryl chlorides, like 4-chloroacetophenone, leads to the formation of dimethyl terephthalate amongst other products arising from organic reactions of methoxide ion and/or CO. Less nucleophilic alcohols such as 2,2,2-trifluoroethanol promote the formation of carbonylation products even from 4-chloroacetophenone and chlorobenzene. Labelling studies involving CD3OH, CD3OD or 13CO give information on the origin of many of the products.

Efficient Carbonylation of Aryl and Heteroaryl Bromides using a Palladium/Diadamantylbutylphosphine Catalyst

“…As shown in Table 1 di-1-adamantyl-n-butylphosphine (cataCXium A) and PA C H T U N G T R E N N U N G (t-Bu) 3 permit efficient butoxycarbonylation of 4-bromoanisole (93-94 %; Table 1, entries 1, 3). 1,1'-Bis(diphenylphosphino)ferrocene (dppf) and the dicyclohexyl-2-(N-mesityl)imidazolylphosphine gave slightly lower yields (70-84 %) of the desired product (Table 1, entries 5, 9).…”

“…[1] Originally, these reactions were established in the mid-1970s by the pioneering work of R. F. Heck and co-workers. [2] Since that time, carbonylations of haloarenes have found a number of applications in organic synthesis, [3] and even related industrial processes, such as the alkoxycarbonylation of a benzylic alcohol toward ibuprofen, have been realized on a multi-1000 ton scale. [4] In the last decade, significant progress with respect to the development of more general and productive palladium catalysts for various coupling reactions has been reported.…”

A General and Efficient Method for the Formylation of Aryl and Heteroaryl Bromides

“…[2] On the other hand, these reactions offer numerous possibilities for the selective synthesis of various aromatic carbonyl compounds (Scheme 1). [3] Aromatic aldehydes are probably the most useful class of products in regard to carbonylations as the highly reactive aldehyde group can be readily employed in numerous CÀC and CÀN coupling reactions, reductions, as well as other transformations. Traditionally, aromatic aldehydes have been synthesized by electrophilic formylation reactions, such as the Vilsmeier-Haack, Gattermann, Gattermann-Koch, ReimerTiemann, and Duff reactions, which use unacceptable amounts of reagents and produce large quantities of side products and waste.…”

Eine allgemeine und effiziente Methode zur Formylierung von Aryl‐ und Heteroarylbromiden

“…[2] Andererseits bieten diese Reaktionen vielfältige Möglichkeiten zur selektiven Synthese von aromatischen Carbonylverbindungen (Schema 1). [3] Dabei sind aromatische Aldehyde wohl die wertvollste Produktklasse, was in der hohen Reaktivität der Aldehydfunktion begründet ist, die den effizienten Einsatz in Reduktionen, C-C-und C-N-Kupplungsreaktionen ermöglicht.…”

“…Bemerkenswert ist die beispiellose Wirkung von Di-1-adamantyl-nbutylphosphin (cataCXium A, 6 a) bei der reduktiven Carbonylierung von 4-Bromanisol (92 %) (Tabelle 1, Eintrag 11). Sogar elektronisch und sterisch vergleichbare Liganden wie Diadamantylbenzylphosphin (cataCXium ABn, 6 b) und P(tBu) 3 (5) [a]…”