The effect of catalyst loading and donor ligands in the Mn(III) salen catalysed chiral epoxidation of chromenes: Synthesis of BRL 55834

Chromium− and Manganese−salen Promoted Epoxidation of Alkenes

“…The ligand structure is now considered to be in the category of ‘privileged' . A stereochemical model for predicting the configuration of the major epoxide enantiomer formed has been detailed as well as an analysis of the substrate properties that should lead to high ee's. , Jacobsen's catalyst has been applied to the syntheses of a range of biologically active compounds ,− including Diltiazem and the side chain of Taxol. , Industrial requirements 133 prompted efforts to reduce the catalyst loading (see sections 3.7 and 3.8 for details). Industrially applicable syntheses of Jacobsen's catalyst have also been published, − and it is commercially available. ,

…”

“…Workers at Smithkline Beecham found that in the AE of chromenes with Jacobsen's catalyst there was a small decrease in ee with time in the absence of donor ligand . Adding N -oxide donor ligands was found to suppress this effect.…”

Recent advances in the trifluoromethylation methodology and new CF3-containing drugs

“…Finally, the target molecule of tafenoquine was obtained by the removal of the original phthalimide protecting group [102].…”

Three‐Membered Heterocycles. Structure and Reactivity

“…Thus, epoxidation of the chromene 378 using catalyst 361 and an oxidant consisting of mCPBA/NMO afforded epoxide 379 in the (3S,4S) configuration, whereas a classical Jacobsen catalyst (357) provided the corresponding (3R,4R) enantiomer. This approach has been applied to the chiral epoxidation of chromene 380 using the readily available chromium salen catalyst 358 in a synthesis of the novel potassium channel activator BRL55834 [422].…”