A New Tetratertiary Phosphine Ligand and Its Use in Pd-Catalyzed Allylic Substitution

Abstract

A new tetraphosphine, the cis-cis-cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane (Tedicyp) 1 has been synthesized, characterized, and used in Pd-catalyzed allylic substitutions. The Tedicyp was easily prepared in seven steps from the commercially available himic anhydride. The structure of the complex Tedicyp-borane was determined by X-ray analysis. The tetraphosphine in combination with [Pd(eta(3)-C(3)H(5))Cl](2) affords a very efficient catalyst for allylic substitution of several allylic acetates. Under mild conditions, very high turnover numbers and turnover frequencies have been obtained.

Cesium carbonate mediated exclusive dialkylation of active methylene compounds

“…In the case of cesium carbonate, the reactions were clean and efficient. Importantly, in the present protocol the dialkylation reaction is free from any side product formation, such as monoalkylated product [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] , O-alkylation 30 and condensation product. Bases like sodium ethoxide, potassium tert-butoxide, potassium phosphate and sodium hydride are known to give rise to considerable O-alkylation in DMF.…”

Direct Arylation of Thiophenes via Palladium‐Catalysed CH Functionalisation at Low Catalyst Loadings

“…In order to obtain more efficient palladium catalysts we have prepared the tetrapodal phosphine ligand, cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane or Tedicyp (Scheme 3) [11] in which the four diphenylphosphino groups are stereospecifically bound to the same face of the cyclopentane ring. Using this ligand, very high turnover numbers (TONs) have been obtained for Suzuki, Heck, Sonogashira or Negishi cross-coupling reactions.…”

“…[11] , aryl halide: 1 mmol, thiophene-2-carbonitrile: 2 mmol, AcONa: 2 mmol, DMAc, 20 h, 150 8C, yield determined by GC and NMR, yields in parenthesis are isolated. …”

“…All reactions were run under argon using vacuum lines in Schlenk tubes in oven-dried glassware. Preparation of the Pd-Tedicyp Catalyst [11] An over-dried 40-mL Schlenk tube equipped with a magnetic stirring bar, under argon atmosphere, was charged with [PdA C H T U N G T R E N N U N G (C 3 H 5 )Cl] 5 (4.2 mg, 11.6 mmol) and Tedicyp (20 mg, 23.2 mmol). 2.5 mL of anhydrous DMAc were added, then the solution was stirred at room temperature for 10 min.…”

High‐Turnover Palladium Catalysts in Cross‐Coupling and Heck Chemistry: A Critical Overview

“…[167] Its catalytic performance is impressive and has been quite extensively explored. Therefore, this ligand warrants a close examination.…”