Enantiomerically pure cycloalkenylacetic acid derivatives via Pd-catalyzed asymmetric allylic alkylation and subsequent enantiomeric enrichment via iodolactones

A New Synthesis Route to Enantiomerically Pure Jasmonoids

“…Compound A was planned to be prepared from lactone 9 which was previously obtained in low selectivity by Pd-catalyzed asymmetric allylic alkylation of cyclopentenyl chloride using second-generation chiral phosphanyloxazoline ligands. [7] With a third-generation phosphanyloxazoline, the ligand L, [8] we now obtained an enantiomeric excess of 95 % ee and a yield of 93 % in the allylic substitution with sodium dimethylmalonate (Scheme 2). The alkylated malonate was converted into the crystalline iodolactone whose enantiomeric purity was increased by recrystallization to > 99.9 % ee.…”

Chiral ferrocene-based phosphine-imine and sulfur-imine ligands for palladium-catalyzed asymmetric allylic alkylation of cycloalkenyl esters

“…(entry 1). However, if the NO 2 group was in meta-position of phenyl ring, a significant increase of the catalytic activity and enantioselectivity was observed and the reaction d The R-configuration was confirmed by comparing the specific rotation with a literature value [9]. gave allylic product with 81% yield and 83% e.e.…”

“…(entry 12). The absolute configuration of product 7a from these reactions was proven to be R by comparing the specific rotation with a literature value [9].…”

“…The residue was purified by column chromatography on a silica gel column (eluted by hexanes:ethyl acetate, 20:1) to afford the pure product 7, e.e.-value for 7 was determined by GC (␤-390 stationary capillary column). The absolute configuration was determined by the specific rotation with a literature value [9].…”

Highly Diastereoselective Synthesis of 2,6‐Di[1‐(2‐alkylaziridin‐1‐yl)alkyl]pyridines, Useful Ligands in Palladium‐Catalyzed Asymmetric Allylic Alkylation

“…The cyclohexenyl carbonate 18 was poorly reactive in the usual experimental conditions and the ee of the derived product 19 [14] was low. For example, using ligand 10ba', a 40 % yield and 6 % ee were achieved, whereas a 68 % yield and 37 % ee were obtained with the ligand 10ae', in both cases after 3 days.…”