261966-94-3Relevant academic research and scientific papers
Palladium-catalysed direct regioselective synthesis of cyclic ketals from electron-rich olefins and aryl bromides in ionic liquids
Hyder, Zeynab,Mo, Jun,Xiao, Jianliang
, p. 1699 - 1704 (2006)
The Heck reaction comprises one of the most important carbon-carbon coupling reactions in organic synthesis. The popularity of the reaction is attributable to the broad availability of aryl halides and to the tolerance of the reaction for a wide variety o
Hydrogen-bond-directed catalysis: Faster, regioselective and cleaner heck arylation of electron-rich olefins in alcohols
Hyder, Zeynab,Ruan, Jiwu,Xiao, Jianliang
experimental part, p. 5555 - 5566 (2009/06/17)
A general method for the regioselective Heck reaction of electronrich olefins is presented. Fast, highly regioselective Pd-catalysed α-arylation of electron-rich olefins, vinyl ethers (1a-d), hydroxyl vinyl ethers (1e,f), enamides (1g,h) and a substituted vinyl ether (1i) has been accomplished with a diverse range of aryl bromides (2a-r), for the first time, in cheap, green and easily available alcohols with no need for any halide scavengers or salt additives. The reaction proceeds with high efficiency, leading exclusively to the a-products, in 2-propanol and particularly in ethylene glycol. In the latter, the arylation can be catalysed at a palladium loading of 0.1 mol% and finish in as short a time as 0.5 h. The remarkable performance of the alcohol solvents in promoting a regiocontrol is attributed to their hydrogen-bond- donating capability, which is believed to facilitate the dissociation of halide anions from PdII, and hence, the generation of a key ionic Pd II-olefin intermediate responsible for the a product. This belief is further strengthened by the study of a benchmark arylation reaction in 21 different solvents. The study revealed that exclusive α-regioselective arylation takes place in almost all of the protic solvents, and there is a rough correlation between the α-arylation rates and the solvent parameter ETN. The method is simpler, cleaner and more general than those established thus far.
Water Soluble Phosphanes, XIV [1]. Hydrophilic Derivatives of Triphenylphosphane with NH2, COOH and P(O)(OR)2 Functionalized Side Chains
Liek, Christian,Machnitzki, Peter,Nickel, Thomas,Schenk, Stefan,Tepper, Michael,Stelzer, Othmar
, p. 1532 - 1542 (2007/10/03)
Nucleophilic phosphanylation of ortho-fluorophenylacetic acid or ortho-fluorobenzylamine with PhPH2 using KOtBu as the base affords the hydrophilic tertiary phosphanes 3 and 4a with terminal CH2-COOH and CH2-NH2 substituents. The corresponding secondary phosphane ligands 2 or 5 may be obtained by Pd-catalyzed P-C coupling of ortho-iodophenylacetic acid with PhPH2 or selective nucleophilic phosphanylation of ortho-fluorophenylacetic acid. Novel phosphonatomethyl derivatives 7a, 7b of triphenylphosphane have been obtained in a two stage synthesis using ortho-iodobenzylchloride or meta-iodobenzylbromide as starting materials. Arbusov reaction with P(OEt)3 and Pd-catalyzed P-C coupling reactions with Ph2PH gave the esters 7a, 7b. Purification of 7a was achieved via its BH3 adduct 8a. Deprotection, hydrolysis and neutralisation with NaOH affords the water soluble sodium salts 9a,9b. α-Hydroxy and α-benzylamino derivatives 12 and 14 of ortho-diphenylphosphanobenzyl phosphonate (e.g. 7a) and the corresponding Me2P(O) analogs 13 and 16 are accessible in a straightforward manner by addition of (MeO)2P(O)H or Me2P(O)H to ortho-phosphanobenzaldehyde 11a or its benzaldimino derivative 15, respectively. An improved synthesis for 11a-11c has been developed. Reaction of 11a with the Wittig reagent Ph3P=C(H)COOEt and subsequent hydrolysis of the intermediate ester 17a affords ortho-diphenylphosphano cinnamic acid 17. The catalytical activity of 1, 9a, 9b and related ligands in Suzuki-type coupling reactions has been investigated.
