Synthesis of fluorescent enone derived α-amino acids

Abstract

The development of a facile and general method for the preparation of enone derived alpha-amino acids is described. The key step involves a Horner-Wadsworth-Emmons reaction between an aspartic acid derived beta-keto phosphonate ester and a range of aldehydes resulting in the formation of highly functionalised alpha-amino acids in good yields. An efficient two-stage deprotection process using mild conditions was developed to give the parent alpha-amino acids. Application of this methodology has produced a novel fluorescent alpha-amino acid that has potential as a biological marker.

Phosphorus-containing amino acids with a P–C bond in the side chain or a P–O, P–S or P–N bond: from synthesis to applications

“…It must be noted that a sterically hindered trityl protecting group is necessary for regioselective addition to the ester of the side chain (Scheme 66). [85][86][87] These authors also reported the synthesis of optically active b-pyridyl . The removal of both the amine and carboxylic acid protecting groups was performed to give the free amino acids.…”

Synthesis of pyrazole containing α-amino acids via a highly regioselective condensation/aza-Michael reaction of β-aryl α,β-unsaturated ketones

“…The reactions were carried out as described for 12 1H, m, 2-H To a solution of methyl (2S)-2-[(benzyloxycarbonyl)amino]-3-(1′,5′-diphenyl-1′H-pyrazol-3′-yl)propanoate (17) (0.09 g, 0.19 mmol) in methanol and water (5 mL, 7 : 3) was added cesium carbonate (0.08 g, 0.25 mmol). The reaction mixture was stirred at room temperature for 16 h before concentrating in vacuo.…”

“…10a Recently, we reported an efficient approach for the preparation of a rare class of α-amino acid with enone side chains. 12 In exploring the reactivity and application of these amino acids, we discovered that these could undergo selective 6-endotrig cyclisations for the synthesis of 4-oxopipecolic acids, 13 and had potential as biological probes with the preparation of a highly fluorescent 4-dimethylamino-1-naphthyl enone analogue. 12 Despite these advances, we found that on long-term storage, the enones were prone to decomposition.…”

Switching the Stereochemical Outcome of 6-Endo-Trig Cyclizations; Synthesis of 2,6-Cis-6-Substituted 4-Oxopipecolic Acids

“…18,19 All reagents and starting materials were obtained from commercial sources and used as received. All dry solvents were purified using a solvent purification system.…”