Stereodivergent Dual Catalytic α‐Allylation of Protected α‐Amino‐ and α‐Hydroxyacetaldehydes

Abstract

Fully stereodivergent dual-catalytic α-allylation of protected α-amino- and α-hydroxyacetaldehydes is achieved through iridium- and amine-catalyzed substitution of racemic allylic alcohols with chiral enamines generated in situ. The operationally simple method furnishes useful aldehyde building blocks in good yields, more than 99% ee, and with d.r. values greater than 20:1 in some cases. Additionally, the γ,δ-unsaturated products can be further functionalized in a stereodivergent fashion with high selectivity and with preservation of stereochemical integrity at the Cα position.

Stereodivergent Allylic Substitutions with Aryl Acetic Acid Esters by Synergistic Iridium and Lewis Base Catalysis

“…Recently, Carreira and co-workers reported the allylation of aldehydes in a stereodivergent fashion by the synergistic reactivity of iridium and amine catalysts under acidic conditions. 3 Zhang and co-workers reported the combination of iridium and zinc catalysts for the related allylation of α -hydroxy phenones. 4 An approach to the stereodivergent allylation of carbonyl compounds in the carboxylic acid oxidation state has not been published.…”

Iridium-Catalyzed Diastereo-, Enantio-, and Regioselective Allylic Alkylation with Prochiral Enolates

“…In a follow-up study, the authors reported that this method tolerates α -heteroatoms ( 47 , R = NPhth or OBn) in similarly high yields and selectivities, though trichloroacetic acid is required as the cocatalyst. 19 …”

Iridium‐Catalyzed Stereoselective Allylic Alkylation Reactions with Crotyl Chloride

“…5–8 We found that the use of proton sponge in place of LiO t -Bu afforded the desired branched product 6 with high regioselectivity (93:7, 6 : 7 ) and diastereoselectivity (7.9:1 dr), though in a modest 66% enantiomeric excess (entry 6). A brief study of ligand frameworks (entries 7–9) 9 revealed 3,3’-diphenyl-phosphoramidite L2 to be optimal.…”