(R)‐ and (S)‐4‐Alkoxy‐2‐tert‐butyl‐2,5‐dihydroimidazole‐1‐carboxylates—New Chiral Glycine Derivatives for Amino Acid Synthesis

Abstract

structure 2 manifests diamagnetic ring current effects: the outer protons are deshielded and the inner shielded. According to the energetic geometrical, and magnetic criteria, the [1,7] H shift transition structure has pronounced aromatic character.

Ab Initio Calculations of the Structure, Kinetics, and Infrared Laser Chemical Reaction Dynamics of Fluorooxirane

“…The stereochemical reaction dynamics of chiral molecules is usually investigated in the framework of the synthesis of relatively complex organic, possibly biologically important molecules including fluorinated species. , Indeed, only relatively few very small, rigid, and compact chiral molecules have been studied in detail with respect to their primary unimolecular reaction pathways. The recently synthesized fluorooxirane 1 is quite an outstanding example.…”

A New Approach to the Synthesis of Piperazinomycin and Bouvardin: Facile Access to Cycloisodityrosine via an Intramolecular SNAr Reaction

“…The reaction of 3-fluoro-4-nitrobenzyl bromide 12 with the lithium azaenolate of 13 gave only a poor yield (<10%) of alkylated product, presumably due to the high acidity of benzylic protons and, more importantly, the presence of multielectrophilic centers in 12 . Blank and Seebach also obtained a moderate yield (30%) in the alkylation of p -nitrobenzyl halides with their glycine template under S N 2 conditions. An attempt to switch the reaction course from S N 2 to a radical anion mechanism failed to give the coupled product 14 .…”

“…However, to the best of our knowledge, the corresponding reaction with a HO organocuprate has not yet been described. The high reactivity of the nitro group toward organometallic reagents may explain the low to moderate yields obtained in the alkylation of p -nitrobenzyl halides 3 …”

“…The high reactivity of the nitro group toward organometallic reagents may explain the low to moderate yields obtained in the alkylation of p-nitrobenzyl halides. 18 Completion of the synthesis of 2b was as follows. Reaction of 15 with N-Boc-L-Tyr using EDC as coupling reagent in the presence of HOBt gave the dipeptide 18 in 97% yield.…”

Conformational Chiral Recognition in a Simple Urea

“…Recently, significant interest has been devoted to the recognition, and analyses of such interactions present in nature [6] in an attempt to aid future design of polyfunctional molecular assemblies, e.g. molecular separation [7,8], gears [9 -11], drug -receptor interactions [12] and crystal engineering [13 -18]. These molecular, and in many cases, chiral recognition processes are also central to life.…”