Enantioselective opening of cyclic vinyl epoxides with organoaluminium reagents catalysed by copper salts

Application of rapidly generated bidentate ligand libraries to zinc catalyzed reductions

“…Compound 10 was made as the N-Boc derivative as previously described [8], and subsequently deprotected by stirring in TFA/CH 2 Cl 2 (1:1). Compounds 5 [9], 11 [10], 12 [10], 14 [11], 15 [11] and 16 [12] were synthesised using established procedures.…”

Asymmetric CarbonCarbon Bond‐Forming Reactions

“…Equey and Alexakis performed the same experiments with commercially available Me 3 Al and ligand ( S , S , aS ) -L59 [376] . Comparable enantiomeric excesses were observed (entries 6 and 7), but the regioselectivities were lower compared with the experiments with the analogue zinc reagent (except for the six -membered ring).…”

Copper‐Catalyzed Asymmetric Allylic Alkylation

“…[63] Half an equivalent of dimethylzinc in the presence of Cu(OTf) 2 (3 mol-%) and (S,RR)-L4 (6 mol-%) could selectively alkylate cyclic epoxides 104-106 with good regio-and enantiocontrol in favour of the S N 2' adducts (Scheme 41). Scheme 41. This latter reaction was performed in a similar fashion by the research group of Alexakis, [55] who deracemized cylcoalkene oxiranes [five-(104) to eight-membered (110) ring substrates] with commercially available trimethylaluminum reagent, affording chiral allylic and homo-allylic alcohols with up to 93 % ee and 99 % ee respectively (Scheme 42). However, regioselectivities in favor of the S N 2Ј adduct were not optimal for each ring-size (at the best 94:6 on the sixmembered ring alkene 108).…”