Indium-Mediated Asymmetric Barbier-Type Allylation of Aldimines in Alcoholic Solvents:  Synthesis of Optically Active Homoallylic Amines

Abstract

[reaction: see text] Chiral aldimines derived from phenylglycinol were diastereoselectively allylated with indium powder/allyl bromide in alcoholic solvents. Both aliphatic and aromatic aldimines provided good yield of the desired products with high diastereoselectivity. A racemization-free protocol for removal of the phenylglycinol auxiliary was also developed. The stereochemical assignment of the homoallylic amine was made by NMR spectroscopy and a transition state model was proposed to explain the selectivity.

Heterogeneous Rate Constants for Indium Mediated Allylations: Cinnamyl Chloride in Ethanol/Water Mixtures

“…14,16,18,32−36 Finally, in step 5 the product of the coupling reaction sometimes can rearrange or further react depending on the solvent, especially protic vs aprotic solvents. 37,38 Furthermore, disproportionation−conproportionation between In 3+ , In + , and In 0 , which is sensitive to solvent, may affect product distribution and yield. 6,39−43 Of these five steps, the heterogeneous reaction of allyl halide at the indium surface, step 2, is the least studied.…”

Enantioselective Synthesis of Angularly Substituted 1-Azabicylic Rings: Coupled Dynamic Kinetic Epimerization and Chirality Transfer

“…The enantiomerically enriched ( R )-1-substituted-3-butenylamines 13a–e were available in three steps from the corresponding aldehyde and ( R )-phenylglycinol by the method of Vilaivan and co-workers. 12,13 Reduction of amide intermediates 14a–e with lithium aluminum hydride delivered aminoketals 9a–e in good overall yields from ketal ester 12 .…”

“…Lead acetate (4.50 g, 10.1 mmol) was added to a solution of (2 R )-2-phenyl-2-[(1′ R )-1′-phenylbut-3′-enylamino]ethanol 12 (2.26 g, 8.45 mmol), CH 2 Cl 2 (15 mL), and MeOH (15 mL) at 0 °C. The mixture was stirred at 0 °C for 30 min.…”

“…Characterization data were consistent with previously reported values. 12 HPLC analysis indicated an enantiomeric excess of 92% [CHIRALCEL OD-H column; flow: 0.5 mL/min; hexanes: i -PrOH:Et 2 NH = 900:100:1; λ = 254 nm; major enantiomer t R = 13.1 min; minor enantiomer t R = 16.8 min]. ${false[\alpha false]}_{589}^{23}+31.0,{false[\alpha false]}_{577}^{23}+32.2,{false[\alpha false]}_{546}^{23}+36.7,{false[\alpha false]}_{435}^{23}+66.5false(c2.64,{\text{CH}}_2{\text{Cl}}_{2}false)$.…”

An efficient preparation of new homoallylamines and α‐aminonitriles bearing furyl and thienyl rings

“…α-Aminonitriles are also important intermediates for several amino acids as well as for popular bifunctional synthons that have found numerous synthetic applications [6]. Both these substructures are usually prepared from azomethines via nucleophilic addition reactions such as the Grignard-Barbier allylations [7][8][9][10] and Strecker-type reactions [11][12][13][14][15][16]. The respective allyl or cyanide ion addition reactions provide an access to new drug-like molecules by introducing a stereogenic center and a carbon-carbon bond in one step.…”