503625-35-2Relevant academic research and scientific papers
Synthesis and screening of new chiral ligands for the copper-catalysed enantioselective allylic substitution
Ongeri, Sandrine,Piarulli, Umberto,Roux, Maryline,Monti, Chiara,Gennari, Cesare
, p. 3388 - 3399 (2002)
The synthesis of the new chiral ligands 6ae, 8ae, 9ae, and 11ae starting from the chiral β[(Boc)amino]-sulfonamide 3ae is reported. The β-amino group of 3ae was deprotected and condensed with 3,5-dichlorosalicylaldehyde (4) to yield the known Schiff base 5ae, which was then reduced to the amino compound 6ae (Scheme 3). Alternatively, condensation of the free amino compound with 2-(diphenylphosphanyl)benz-aldehyde (7) afforded the imino ligand 8ae which upon reduction yielded the amino ligand 9ae (Scheme 4). The free amino compound derived from 3ae was also coupled with 2-(diphenylphosphanyl)benzoic acid (10) to give ligand 11ae (Scheme 5). These ligands were tested in the copper-catalysed allylic substitution reaction of cinnamyl (= 3-phenylprop-2-enyl) phosphate 12 with diethylzinc as a nucleophile. Ligands 5ae, 6ae, 8ae, and 11ae gave excellent ratios (100:0) of the SN2′/SN2 products (Scheme 6 and Table 1). Ligand 11ce, identified from the screening of a small library of ligands of general formula 11, promoted the allylic substitution reaction with moderate enantioselectivity (40% for the SN2′ product 13 (Scheme 8 and Table 3)).
Discovery of a new efficient chiral ligand for copper-catalyzed enantioselective Michael additions by high-throughput screening of a parallel library
Chataigner, Isabelle,Gennari, Cesare,Ongeri, Sandrine,Piarulli, Umberto,Ceccarelli, Simona
, p. 2628 - 2634 (2007/10/03)
A combinatorial library of 125 chiral Schiff base ligands 5 was synthesized with the use of solutionphase parallel synthesis and solid-phase extraction (SPE) techniques to scavenge excess reagents and reaction by-products and avoid chromatography. The syn
Discovery of a new efficient chiral ligand for copper-catalyzed enantioselective Michael additions by high-throughput screening of a parallel library
Chataigner, Isabelle,Gennari, Cesare,Piarulli, Umberto,Ceccarelli, Simona
, p. 916 - 918 (2007/10/03)
The optimal ligand 1 for the enantioselective copper-catalyzed 1,4- addition of Et2Zn to cyclic enones [Eq. (1)] was established by multisubstrate (high-throughput) screening of a parallel library of chiral Schiff base ligands. The screening data show how the ligand structure is finely tuned by mutual influences of stereogenic center a (which controls the absolute configuration of the reaction product), stereogenic center b, and the substitution pattern of the aromatic ring.
