1871-73-4Relevant academic research and scientific papers
Stereoselective Synthesis of Some γ- and δ-Fluoro-α-amino Acids
Kroeger, Stefan,Haufe, Guenter
, p. 1201 - 1206 (2007/10/03)
(R)-(-)-2-Amino-4-fluorobutyric acid (4c) (32percent ee) and six of its homologues 9 have been synthesized by diastereoselective alkylation (54-72percent yield) of (R)-(+)-camphor-based glycine ester imines 1 with 1-bromo-2-fluoro-alkanes 6, at low temperature, followed by deprotection.Similarly 1-bromo-3-fluoropropane was used for the preparation of (R)-(-)-5-fluoronorvaline (4d) (42percent ee).With 1-bromo-2-fluoropropane (6a) and its homologues (prepared by bromofluorination of 1-alkenes) partial resolution occurs in the alkylation step, yielding mixtures of four diastereomers.Using (R)-1-bromo-2-fluoro-4-methylpentane two diastereomeric alkylation products are formed (58percent de).The overall yield of the three-step procedure varied from 10percent to 32percent. - Keywords: Chiral auxiliaries; Glycine ester imines; Alkylations; Bromofluoro alkanes; Triethylamine tris(hydrofluoride)
A Rapid and Efficient Method for the Fluoroalkylation of Amines and Amides. Development of a Method Suitable for Incorporation of the Short-Lived Positron Emitting Radionuclide Fluorine-18
Chi, Dae Yoon,Kilbourn, Michael R.,Katzenellenbogen, John A.,Welch, Michael J.
, p. 658 - 664 (2007/10/02)
We have described a two-step method for the preparation of fluoroalkyl-substituted amines and amides.The sequence involves fluoride ion displacement of a haloalkyl trifluoromethanesulfonate (triflate), followed by fluoroalkylation of the heteroatom system (amine or amide) by the fluoroalkyl halide.Alternatively, the fluoroalkyl halide can be prepared by halofluorination of a terminal olefin.These reactions have been used to prepare various fluoroalkyl derivatives of N-phenylpiperazine and N-fluoroalkyl derivatives of the neuroleptic agent spiperone (7).The sequence is rapid, convenient, and efficient, even when fluoride ion is the limiting reagent.Therefore, it is readily adaptable to the preparation of a variety of compounds labeled with the short half-life (t1/2 = 110 min) positron-emitting radionuclide fluorine-18.
FLUORINATION OF HALOGENO ALCOHOLS WITH 1,1,2,3,3,3-HEXAFLUOROPROPYL DIETHYLAMINE
Watanabe, S.,Fujita, T.,Usui, Y.,Kimura, Y.
, p. 135 - 142 (2007/10/02)
Fluorination of halogeno alcohols with 1,1,2,3,3,3-hexafluoropropyl diethylamine (PPDA) was investigated. 2-Bromo-1-fluorobutane was obtained from the reaction of PPDA and 2-bromo-1-butanol (yield 50percent).Similar results were obtained from other alipha
