Selective Synthesis of New Fluorinated Alicyclic β‐Amino Ester Stereoisomers

Abstract

New fluorinated alicyclic β-amino ester stereoisomers with a cyclohexene or cyclohexane skeleton were prepared from cis-or trans-2-aminocyclohex-3-enecarboxylic acids in five or six steps through a regio-and stereoselective hydroxyl-

Efficient regio- and stereoselective access to novel fluorinated β-aminocyclohexanecarboxylates

“…The reaction was carried out under different experimental conditions, with variation of the temperature (−40 °C, 0 °C or 20 °C) and the solvent (toluene, CH 2 Cl 2 or THF). Finally, it was found that hydroxylated amino ester 5 underwent inversion on reaction with a 50% Deoxo-Fluor toluene solution in CH 2 Cl 2 at 0 °C [68–69] to give monofluorinated cyclohexane amino ester 7 in 32% yield (Scheme 2). This rather modest yield is attributed to the relatively large amount of elimination materials (40% overall).…”

Selective Synthesis of Fluorine‐Containing Cyclic β‐Amino Acid Scaffolds

“…Iodolactonization of cis ‐amino acid (±)‐7 followed by HI elimination and lactone opening with NaOEt, at 0 °C or 20 °C, gave hydroxylated cyclohexene amino ester isomers (±)‐8 and (±)‐9 with the hydroxy group located in position at C‐5 on the carbocycle. Analogously, trans ‐amino acid (±)‐10 with similar iodolactonization procedure afforded hydroxylated β‐amino ester isomer (±)‐11 (Scheme ) …”

“…Interestingly, hydroxylated amino ester (±)‐6 gave the same fluorine‐containing amino ester (±)‐13 . It is formed in an S N 2’ process, when the fluoride axial attack takes place at the sp 2 C‐5 carbon with simultaneous displacement of the hydroxy function (Scheme ) ,…”

Fluorination of some functionalized cycloalkenes through epoxidation and oxirane opening with Deoxofluor or XtalFluor-E

“…Because of the high importance of fluorinated biomolecules in drug design, the introduction of one or more fluorine atoms into an organic molecule has attracted high interest over the past ten years [6][7][8][9][10]. In view of the significance of a fluorine atom in an organic molecule, epoxide opening with fluoride, without doubt, is a highly useful approach for the introduction of a fluorine atom into a certain molecule [11][12][13].…”