Fluorous Oxime Palladacycle: A Precatalyst for Carbon–Carbon Coupling Reactions in Aqueous and Organic Medium

Abstract

To facilitate precatalyst recovery and reuse, we have developed a fluorous, oxime-based palladacycle 1 and demonstrated that it is a very efficient and versatile precatalyst for a wide range of carbon-carbon bond formation reactions (Suzuki-Miyaura, Sonogashira, Stille, Heck, Glaser-type, and Kumada) in either aqueous or organic medium under microwave irradiation. Palladacycle 1 could be recovered through F-SPE in various coupling reactions with recovery ranging from 84 to 95% for the first cycle. Inductively coupled plasma optical emission spectrometry (ICP-OES) analyses of the Pd content in the crude product from each class of transformation indicated extremely low levels of leaching and the palladacycle could be reused four to five times without significant loss of activity.

Dramatic solvent and concentration dependence in the reaction of (anthracen-9-yl)methanamines with suitable electron-deficient acetylenes

“…As expected, product distribution changed under different conditions. However, a few products arising through either single electron transfer mediated transformations such as 9‐methylanthracene ( 7 ), 9‐anthraldehyde ( 6 ), 1,2‐bis(9‐anthracenyl)ethane ( 8 ) and lepidopterene ( 9 ) or through reaction with adventitious oxygen such as 9,10‐anthraquinone ( 5 ) were common in all reactions (Chart ). In most cases, acetylenes underwent oligomerization to intractable residues.…”

(Anthracen-9-yl)methyl sulfides as a mechanistic probe for chemical as well as photochemical electron-transfer reactions

“…Various fractions were collected and analyzed using spectroscopic measurements. The products formed were identified as 9-anthraldehyde (3), 63 9,10-anthraquinone (6), 64 9-methylanthracene (12), 65 1,2-bis(9-anthracenyl)ethane (13), [66][67][68][69] lepidopterene (14), 66,[70][71][72][73][74] biplanene (15), [75][76][77] anthrone (16) 78 along with products arising through the S-alkyl residues present in parent anthracenemethyl sulfides. Common products formed in the photoirradiation of (anthracen-9-yl)methyl sulfides 1a-f are shown in Chart 2 and details of all the products isolated are presented in Scheme 3.…”

Fluorous Organometallic Chemistry

“…In 2011, a series of luminescent iridium(III) biscyclometalated cations [Ir(N-C) 2 (N-N)](PF 6 ) with two C 8 F 17 ponytails were reported, in which the fluorous substituents appeared to impact positively on the photophysical and biological properties [121]. The oxime-based palladacycle (24), formed in a slow reaction of the free oxime with Li 2 PdCl 4 in acetone at reflux, has been shown to be a highly effective pre-catalyst for SuzukiMiyaura, Sonagashira, Stille, Heck and Kumada reactions, either in aqueous solution or organic solvents, that could be recycled and reused up to five times [122,123]. The first metal-pincer ligand complex was reported in 1998.…”