Flash vacuum pyrolysis of stabilised phosphorus ylides. Part 17.1 Preparation of aliphatic amino acid derived γ-alkoxycarbonylamino-β-oxo ylides and pyrolysis to give α,β-acetylenic γ-amino acid and GABA analogues
作者:R. Alan Aitken、Nazira Karodia、Tracy Massil、Robert J. Young
DOI:10.1039/b110243e
日期:2002.2.6
A series of eleven α-aminoacyl stabilised phosphorus ylides 9â19 have been prepared by condensation of N-alkoxycarbonyl protected amino acids with Ph3PCHCO2Et using a carbodiimide peptide coupling reagent. Upon flash vacuum pyrolysis at 600 °C, these undergo extrusion of Ph3PO to give the corresponding α,β-acetylenic γ-amino esters 21â29, 33 and 34 in moderate yield. In two cases the terminal alkynes 30 and 31 are also formed. The β-aminoacyl ylide 20 from β-alanine
similarly gives the α,β-acetylenic δ-amino ester 35 upon pyrolysis. Regioselective addition of HBr to the triple bond of one acetylenic ester 25 was observed giving a mixture of E and Z
α-bromoacrylates 36. Hydrogenation of the N-Cbz acetylenic esters 21â23 and 33 results in N-deprotection and hydrogenation of the triple bond to afford the chiral GABA analogues 37â40 in 70 â>95% ee as determined by 19F NMR of their Mosher amides. Fully assigned 13C NMR spectra of all the ylides and acetylenic ester derivatives are presented.
Synthesis of chiral branched allylamines through dual photoredox/nickel catalysis
作者:Mateusz Garbacz、Sebastian Stecko
DOI:10.1039/d1ob01624e
日期:——
photoredox approach and Ni catalysis. The reaction proceeds under mild conditions, under blue light irradiation, and in the presence of an organic dye, 4CzIPN, as a photocatalyst. The scope of suitable reaction partners is broad, including alkyl bromides bearing reactive functionalities (e.g., esters, nitriles, aldehydes, ketones, epoxides) and N-protected allylamines, as well as N-allylated secondary and tertiary
烯丙胺是合成各种天然产物和药物的通用构件。与末端烯丙胺相比,其具有内部立体定义双键的支链同系物的合成方法研究较少。这项工作描述了一种通过将光氧化还原方法和 Ni 催化相结合,将烷基溴与简单的 3-溴烯丙胺交叉偶联来制备烯丙胺的新方法。该反应在温和的条件下,在蓝光照射下,在有机染料 4CzIPN 作为光催化剂的存在下进行。合适的反应伙伴的范围很广,包括带有反应性官能团的烷基溴(例如,酯、腈、醛、酮、环氧化物)和N-保护的烯丙胺,以及N-烯丙基化的仲胺和叔胺和杂环。使用非外消旋起始材料可以快速简单地构建复杂的多功能烯丙胺衍生物,而不会损失对映体纯度。
Synthesis of Acylborons by Ozonolysis of Alkenylboronates: Preparation of an Enantioenriched Amino Acid Acylboronate
作者:Jumpei Taguchi、Toshiki Ikeda、Rina Takahashi、Ikuo Sasaki、Yasushi Ogasawara、Tohru Dairi、Naoya Kato、Yasunori Yamamoto、Jeffrey W. Bode、Hajime Ito
DOI:10.1002/anie.201707933
日期:2017.10.23
functionalized acylborons are prepared by ozonolysis of alkenyl MIDA boronates. The first synthesis of α-amino acylborons, including the enantiopure alanine-type acylboron was achieved using this method. The products are essential for protein–protein conjugation by potassium acyltrifluroborate ligation. Oligopeptide synthesis using α-amino acylborons proceeded in dilute aqueous medium and the alanine-type acylboron