Synthetic Routes to Late Transition Metal–NHC Complexes

Synthesis, in silico and in vitro Evaluation of Novel Oxazolopyrimidines as Promising Anticancer Agents

“…Yield: 12.50 g, 90 %. Spectral and elemental analysis data are identical to literature reports [27–30] …”

“…Compounds 7a and 7b were obtained by Suzuki–Miyaura cross coupling reaction of 7‐ N ‐Boc‐piperazine‐substituted oxazolo[4,5‐ d ]pyrimidine 6 with the corresponding arylboronic acids in the presence of [Pd(μ‐Cl)Cl(IPr)] 2 (0.5 mol‐%), EtOH and K 2 CO 3 (IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene; Scheme 2). [27–30] N ‐Boc‐protection was removed by reacting 6 or 7a / 7b with CF 3 COOH under an inert atmosphere resulting in the formation of oxazolo[4,5‐ d ]pyrimidin‐7‐yl)‐piperazin‐1‐ium trifluoroacetates 8a – 8c . Compounds 8a – 8c reveal in their 1 H‐NMR spectra a resonance at 9.04–9.16 ppm corresponding to H 2 N + functionality in the piperazine moiety, and their 19 F‐NMR spectra in (D 6 )DMSO revealed a singlet at −73.5 ppm.…”

Continuous Flow Synthesis of Metal–NHC Complexes**

“…The surprising stability of the metal–NHC bond has also permitted the study and use of transition metal–NHC complexes in medicinal chemistry [2] and most recently in materials science [3] . The nowadays ubiquitous use of this fascinating class of ligands has been a driving force encouraging the development of sustainable, efficient and user‐friendly routes leading to their syntheses [4] …”

“…Both the transmetallation and the built-in base routes have as their main disadvantage al ow atom economy and, considering the transmetallation, the use of Ag I species which are notoriously light-sensitive, also represents ar esource depleting factor.I no rder to overcomet he limitations highlighted by the three synthetic routes described above,t he last decade has seen the development of what we now commonly call the weak-base route. [4] This approachi nvolves the use of weaka nd inexpensive bases such as K 2 CO 3 ,N aOAco rN Et 3 ,t he starting azolium salt and am etal precursor of interest. The main benefits of this synthetic strategy lie in the possibility of carrying out the reactions under air,i nasingle step, with high atom efficiency and using technical grade green solvents (e.g.…”

Measuring the Olefin‐to‐Pd(0) Bond Strength: A Kinetic Study Involving Olefin Exchange Reactions on Palladium(0) Complexes Bearing Isocyanide Ligands

“…A particularly advantageous feature of this class of compounds is the easily achievable interconversion between the most stable two palladium oxidation states 0 and +2. This property allows to trigger oxidative addition and reductive elimination processes which are almost ubiquitous steps in homo and hetero‐cross coupling reactions [2–13] . It has become apparent that in these systems the real catalyst is an unsaturated PdL 2 or PdL species usually produced in situ from a bench‐stable pre‐catalyst [14] .…”