Novel observation concerning the nitrobenzenesulfonamide protecting group
摘要:
In an ongoing work directed towards the synthesis of nucleoside derivatives containing an L-alanine residue, we report herein a novel observation concerning the Ns-protecting group: the epimerization of the alpha-hydrogen in acylation conditions. (c) 2006 Elsevier Ltd. All rights reserved.
α-amino acids, which are first transformed into N-allyl-α-amino ketones through conventional methodologies. Then, a one-pot sequence that involves formation of a tosylhydrazone from the ketone, base-induced decomposition of the hydrazone, and intramolecular 1,3-dipolar cycloaddition of the diazo compound generated, gives rise to the bicyclic systems with total diastereoselectivity and high preservation
3,5-Bis(n-perfluorooctyl)benzyltriethylammonium Bromide (F-TEBA): An Efficient, Easily Recoverable Fluorous Catalyst for Solid-Liquid PTC Reactions
作者:Gianluca Pozzi、Voichiţa Mihali、Francesca Foschi、Michele Penso、Silvio Quici、Richardâ H. Fish
DOI:10.1002/adsc.200900631
日期:2009.12
reacted under mildconditions to give 3,5-bis(n-perfluorooctyl)benzyltriethylammonium bromide (F-TEBA), an analogue of the versatile phase-transfer catalyst, benzyltriethylammonium chloride (TEBA), containing two fluorous ponytails. This perfluoroalkylated quaternary ammonium salt was successfully employed as a catalyst in a variety of reactions run under solid-liquidphase-transfercatalysis (SL-PTC) conditions
A General Approach to Dehydro-Freidinger Lactams: Ex-Chiral Pool Synthesis and Spectroscopic Evaluation as Potential Reverse Turn Inducers
作者:Tobias Hoffmann、Reiner Waibel、Peter Gmeiner
DOI:10.1021/jo0261653
日期:2003.1.1
Starting from natural alpha-amino acids, a practical synthesis of the dehydro-Freidinger lactams 9a-h based on the ring-closing olefin metathesis reaction was investigated. The presented examples comprise 6-, 7-, 8-, 9-, and 10-membered cyclic dipeptide mimics. Structural variations were demonstrated. We approached the metathesis precursors 8a-h employing an N-alkylation/peptide-coupling strategy.
Macrocyclic peptidomimetic inhibitors of β-secretase (BACE): First X-ray structure of a macrocyclic peptidomimetic-BACE complex
作者:Isabel Rojo、José Alfredo Martín、Howard Broughton、David Timm、Jon Erickson、Hsiu-Chiung Yang、James R. McCarthy
DOI:10.1016/j.bmcl.2005.09.003
日期:2006.1
The synthesis of novel macrocyclic peptidomimetic inhibitors of the enzyme BACE1 is described. These macrocycles are derived from a hydroxypthylene core structure. Compound 7 was co-crystallized with BACE1 and the X-ray structure of the complex elucidated at 1.6 angstrom resolution. This molecule inhibits the production of the A beta peptide in HEK293 cells overexpressing APP751sw. (c) 2005 Elsevier Ltd. All rights reserved.