Simple Derivatives of Natural Amino Acids as Chiral Ligands in the Catalytic Asymmetric Addition of Phenylacetylene to Aldehydes

Abstract

Optically active propargylic alcohols are important chiral building blocks in asymmetric synthesis, and asymmetric addition of terminal alkynes to aldehydes is one of the most important and interesting procedures by which to prepare these chiral building blocks. In this work we have identified some simple derivatives of (S)-proline and other natural amino acids as chiral ligands that can be combined with

Binding abilities of a chiral calix[4]resorcinarene: a polarimetric investigation on a complex case of study

“…We found that CAP −1 is dextrorotatory, with a molar optical rotation Θ 1 as large as +6.5 ± 0.1 deg dm −1 M −1 ; by contrast, CAP −2 , CAP −3 and CAP −4 resulted laevorotatory, with molar optical rotation values as large as Θ 2 = −19.3 ± 0.4 deg dm −1 M −1 , Θ 3 = −20.1 ± 0.3 deg dm −1 M −1 , Θ 4 = −21.5 ± 0.4 deg dm −1 M −1 , respectively. These results appear quite interesting when compared with the value of the molar optical rotation of N -benzyl-L-proline, which can be deduced from literature data [56], namely −19.9 deg dm −1 M −1 . If the optical activity of the macrocycle would merely depend on the presence of the amino acid moieties, then a molar optical rotation as large as ca.…”

Synthesis of 4,4′-biquinazoline alcohols as chiral catalysts in enantioselective alkynylation of aldehydes with phenyl acetylene

“…3i,l,6 Wang et al found that complexes of sulfonamide alcohols and Ti(OiPr) 4 also catalyze the highly enantioselective addition of phenylacetylene to both alkyl and aromatic aldehydes. 7 Other chiral ligands, including amino alcohols, 3n,8 oxazoline, 9 ferrocenyl-substituted aziridinylmethanols 3h,10 and amino acids 11 have also been reported to catalyze this asymmetric addition reaction. New structural motifs play important roles in determining enantioselectivities and reactivities for a given transformation.…”

“…Calcd for C 15 H 12 N 2 O 2 :C, 71.42; H, 4.79; N, 11.10. Found: C, 71.32; H, 4.84; N,11.00; ½a 20 D ¼ þ66 (c 1, EtOH); ee: 99%; retention time: 12.9 min, Chiralcel OD-H, n-hexaneiPrOH, 90:10, flow rate of 1 mL/min, 254 nm.4.3.5. (S)-2-(1-Hydroxy-2-phenylethyl)quinazolin-4(3H)-one 5eCrystallization from a mixture of EtOAc-hexane gave colorless needles.…”

Discovery of anthranilamides as a novel class of inhibitors of neurotropic alphavirus replication

“…Enantiomers 18 were synthesized in a similar fashion, first by acylating proline under classical Schotten-Baumann conditions 33, 34 followed by amide coupling with ethyl isonipecotate (Scheme 3). Hydrolysis of the ethyl ester through a non-racemizing protocol 35 provided the carboxylic acid, and amidation with 4-(2-aminoethyl)pyridine gave the desired ( R )- and ( S )- benzoyl analogues.…”