87905-98-4Relevant articles and documents
Synthesis and Structural Elucidation of 1,2-Disubstituted 3-Fluoropiperidines
Evans, Paul,Fischer, Pauline,Müller-Bunz, Helge,Morris, Morgan
, (2020/02/28)
The work described details the reaction between Selectfluor and a series of 1-carbonyloxy and 1-sulfonyl 2-piperidines in order to generate 3-fluoro-2-methoxypiperidines 3a–f. Their subsequent reaction with allyltrimethylsilane, in the presence of BF3 and TiCl4, is then reported. Studies involving a combination of single-crystal X-ray crystallography and NMR spectroscopy indicate that the allylation process is cis-selective for both carbamate and sulfonamide variants and that optimal levels of diastereoselectivity are obtained using the N-2-nitrobenzene sulfonyl (2-Ns) group. In this manner, the synthesis of a series of 2-allyl 3-fluoro-substituted piperidines (5a, c–f) was achieved. The conversion of both the cis and trans-N-tosyl adducts (5d) into 3-fluorinated analogues of the natural products pelletierine (10) and coniine (11) is subsequently detailed.
Maleimide-based metal-free ligation with dienes: A comparative study
Bailly, Laetitia,Frisby, Axel,Le Nahenec-Martel, Patricia,Lossouarn, Alexis,Renard, Pierre-Yves,Renault, Kévin,Sabot, Cyrille
, p. 3874 - 3887 (2020/06/03)
A brief literature survey reveals that metal-free ligation such as the maleimide-based cycloaddition with electron-rich (hetero)dienes is a widespread tool for the assembly of (bio)molecular systems with applications in biotechnology, materials science, polymers and bio-organic chemistry. Despite their everyday use, only scattered data about their kinetics as well as the stabilities of corresponding products under physiological conditions, are accessible. These key parameters are yet, of paramount importance to ensure the rapid and effective preparation of stable compounds. Herein is reported a systematic study regarding the different classes of dienes used in chemoselective ligation, including their accessibility and stability, as well as comparative kinetic experiments and products stability assays. We took advantage of these data to develop a double labeling strategy from the combined use of cyclopentadiene and oxazole dienes.
Strategies for the Asymmetric Construction of Pelletierine and its Use in the Synthesis of Sedridine, Myrtine, and Lasubine
Zaidan, Raed K.,Evans, Paul
, p. 5354 - 5367 (2019/06/25)
Three methods for the asymmetric synthesis of both enantiomers of pelletierine 6 are reported. Bella's proline-based Mannich process gave (R)- and (S)-Cbz-protected 6 in good yields from Δ1-piperideine 14 and in reasonable enantiomeric excess (74–80 % ee). An intramolecular aza-Michael, cinchona-based, organocatalytic method is also reported. With commercially available 9-amino quinine (24a) and quinidine (24b) catalysts, Cbz-protected α,β-unsaturated ketone 23 also gave (R)- and (S)-Cbz-protected 6 in good yields and enantiomeric excess (90–99 % ee). This material was used to synthesize both optically active forms of deoxyhalofuginone (26), an analogue of febrifugine which is of interest as an anti-fibrotic agent. Finally, a resolution of racemic pelletierine using (R)- and (S)-mandelic acid 27 is reported. This scalable method gave both enantiomers of Cbz- and Boc-protected 6 in excellent enantiomeric excess (≥ 99 %). Both highly enantioenriched forms of 6 (obtained from the resolution study) were used to synthesize several alkaloids. Firstly, (–)-(S)-Cbz-protected pelletierine 17 was used to prepare naturally occurring sedridine (32) and its epimer allosedridine (8). Then the preparation of both enantiomers of the quinolizidine myrtine (33) by an olefination-intramolecular aza-Michael sequence is reported. Finally, the synthesis of the epimeric quinolizidine alkaloids, lasubine I (34) and lasubine II (35), from (+)- and (–)-Boc-protected pelletierine (29) respectively, is discussed.
Synthesis method of double different protected amino acids
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Paragraph 0016, (2019/07/04)
The invention relates to a synthesis method of double different protected amino acids.The technical problems of harsh reaction conditions, inapplicability of production enlarging and the like in an existing synthesis method are mainly solved. According to the technical scheme, the synthesis method of double different protected amino acids comprises the following steps: one of Boc20, Alloc-Cl or Cbz-Osuis added to amino alcohol under the action of an alkaline reagent to obtain a compound 1; the compound 1 reacts with methanesulfonyl chloride or paratoluensulfonyl chloride to obtain an intermediate, then a halide is added into acetone, heating and refluxing are executed to obtain a compound 2; the compound 2 is condensed with diethyl acetamidomalonate under the action of an alkaline agent togenerate a compound 3; the compound 3 is dissolved in alcohol and water, an inorganic base is added, heating, hydrolyzing and decarboxylating are executed to obtain a compound 4; acetylase is added into deionized water to obtain a compound 5 through enzymolysis; amino acid protection is executed, wherein one of Fmoc-Osu, Cbz-OSu, Alloc-Cl or Boc20 is added into thecompound 5 under the action of an alkaline agent to generatea target compound A.
Asymmetric synthesis of (?)- and (+)-neodichroine/hydrachine A from (+)- and (?)-febrifugine
Smullen, Shaun,Evans, Paul
, p. 1627 - 1629 (2018/03/29)
A new asymmetric approach to both enantiomers of the quinazolinone-containing natural product febrifugine is reported. Utilising a proline-mediated aminooxylation-Horner-Wadsworth-Emmons sequence provides the key optically active 2,3-disubstituted piperidine intermediate 7 in high enantioselectivity but poor overall yield (7 steps, 3%, 98% ee). This intermediate has been used to prepare both naturally occurring (+)-febrifugine (1) and its (?)-enantiomer. In turn, each were then used to synthesise, for the first time, both enantiomers of the claimed natural product neodichroine/hydrachine A. Spectroscopic data for the synthetic compound matched the claimed structure. However, the specific rotation differed in both magnitude and sign from the isolation work.
Simple and Practical Real-Time Analysis of Solid-Phase Reactions by Thin-Layer Chromatography
Wu, Chia-Hui,Chen, Chun C.,Lin, Su-Ching,Wang, Cheng-Chung
supporting information, p. 1430 - 1436 (2018/05/15)
Solid-phase synthesis is a practical approach for simplifying the time-consuming and routine purification steps in the preparation of numerous naturally occurring molecules; however, studying such reactions is difficult due to the lack of a convenient monitoring method. By using thin-layer chromatography in conjunction with a photolabile linker on a resin, we developed a convenient and simple method for monitoring solid-phase reactions in real time by thin-layer chromatography. This method provides a user-friendly protocol for examining reaction conditions for solid-state syntheses.
Orthoester in Cyclodehydration of Carbamate-Protected Amino Alcohols under Acidic Conditions
Park, Heemin,Kwon, Yongseok,Shin, Jae Eui,Kim, Woo-Jung,Hwang, Soonho,Lee, Seokwoo,Kim, Sanghee
supporting information, p. 2761 - 2767 (2017/06/13)
The first acid-promoted reaction system to form azaheterocycles from N -carbamate-protected amino alcohols is described. The reaction involves the activation of the hydroxyl group via the use of orthoesters. Despite the reduced nucleophilicity of carbamate nitrogen, this reaction system provides several types of pyrrolidines and piperidines in good to high yields. Using this protocol, prolinol derivatives can also be synthesized from carbamate-protected amino diols with regio- and stereoselectivity.
Pushing the limits of automated glycan assembly: Synthesis of a 50mer polymannoside
Naresh,Schumacher,Hahm,Seeberger
supporting information, p. 9085 - 9088 (2017/08/17)
Automated glycan assembly (AGA) enables rapid access to oligosaccharides. The overall length of polymers created via automated solid phase synthesis depends on very high yields at every step to obtain full length products. The synthesis of long polymers serves as the ultimate test of the efficiency and reliability of synthetic processes. A series of Man-(1 → 6)-α-Man linked oligosaccharides up to a 50mer, the longest synthetic sequence yet assembled from monosaccharides, has been realized via a 102 step synthesis. We identified a suitable mannose building block and applied a capping step in the final five AGA cycles to minimize (n - 1) deletion sequences that are otherwise difficult to remove by HPLC.
Iron-catalyzed borylation of alkyl, allyl, and aryl halides: Isolation of an iron(I) boryl complex
Bedford, Robin B.,Brenner, Peter B.,Carter, Emma,Gallagher, Timothy,Murphy, Damien M.,Pye, Dominic R.
supporting information, p. 5940 - 5943 (2015/01/08)
Activation of B2pin2 with tBuLi facilitates the Fe-catalyzed borylation of alkyl, allyl, benzyl, and aryl halides via the formation of Li[B2pin2(tBu)] (1). The reaction of 1 with a representative iron phosphine precatalyst generates the unique iron(I) boryl complex [Fe(Bpin)(dpbz)2] (2).
SUBSTITUTED TRICYCLIC COMPOUNDS WITH ACTIVITY TOWARDS EP1 RECEPTORS
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Page/Page column 75, (2013/10/22)
The present invention belongs to the field of EPl receptor ligands. More specifically it refers to compounds of general formula (I) having great affinity and selectivity for the EPl receptor. The invention also refers to the process for their preparation, to their use as medicament for the treatment and/or prophylaxis of diseases or disorders mediated by the EPl receptor as well as to pharmaceutical compositions comprising them.
