First Heck Reaction with Arenediazonium Cations with Recovery of Pd-Triolefinic Macrocyclic Catalyst

Abstract

The air- and moisture-stable phosphine-free palladium(0) complex 1 is a highly active and recoverable catalyst for Heck olefination of aryl diazonium tetrafluoroborates. The reactions were performed under aerobic conditions at room temperature to give the coupling products in excellent yields. [reaction: see text]

15-Membered triolefinic macrocycles, their coordination chemistry with transition metals, and the catalytic properties of their palladium metal complexes. A review.

“…The presence of three isopropyl groups in the benzenesulfonyl moiety improves containing ferrocenyl (1ggi, 1gii, 1iii, 1iip, and 1ipp), thienyl (1ggh, 1ghh) and 4-(pyrrol-1-yl)phenyl (1iip, 1ipp, and 1ggp) units have interest for electrochemical purposes. 9,11,12 From the point of view of applications of solid supports in catalysis, 1aab has been used to prepare polymer 1aac by copolymerization with styrene and divinylbenzene (vide infra). 6 We have also prepared macrocycle 1jjj, featuring three fluorine atoms, that is a key intermediate for the synthesis of more elaborated macrocycles through aromatic nucleophilic substitution of the three fluorine atoms with phosphorus (1kkk), nitrogen (1nnn, 1ooo), and sulphur (1lll, 1mmm) nucleophiles.…”

“…Thus, we have prepared a large amount of different transition metal macrocyclic complexes ( Table 2). The palladium complexes 4 are obtained either by ligand-exchange using Pd(PPh 3 ) 4 or Pd(dba) 2 as sources of metal 4,6,8,[11][12][13][14][15] or by in situ reduction of PdCl 2 with hydrazine in the presence of the macrocycle. 10 Excellent results …”

“…Indeed, complex 4ggi efficiently catalyzed 11 the arylation of acrylates and styrene with different arenediazonium tetrafluoroborates 27a-g in ethanol at room temperature (Scheme 7). Recovery of 4ggi by column chromatography was …”

“…Thus, compounds 4 catalyze Suzuki-type cross couplings, 6 Heck reactions, 11 hydroarylation of alkynes, 15 and telomerization of butadiene. 8,14 The mechanisms of catalysis are different, and in some cases are far from clear.…”

ESI-mass spectrometry as a tool for investigating the mechanistic role of a 15-membered triolefinic macrocyclic palladium(0) complex in the Heck reaction

“…In 2003 we published on the high catalytic activity of one of these palladium(0) complexes of type 2 (specifically 2a) for the Heck reaction of arenediazonium salts with acrylates and styrene under mild reaction conditions (Scheme 1). 2 The phosphane-free palladium(0) complex 2a was recovered quantitatively by column chromatography at the end of the reaction. Scheme 1.…”