496790-43-3Relevant academic research and scientific papers
Improved access to chiral tetranaphthoazepinium-based organocatalysts using aqueous ammonia as nitrogen source
Manaprasertsak, Auraya,Tharamak, Sorachat,Schedl, Christina,Roller, Alexander,Widhalm, Michael
supporting information, (2019/11/05)
The class of 3,30-diaryl substituted tetranaphthobisazepinium bromides has found wide application as highly efficient C2-symmetrical phase-transfer catalysts (PTCs, Maruoka type catalysts). Unfortunately, the synthesis requires a lar
Free radical-mediated aryl amination and its use in a convergent [3 + 2] strategy for enantioselective indoline α-amino acid synthesis
Viswanathan, Rajesh,Prabhakaran, Erode N.,Plotkin, Michael A.,Johnston, Jeffrey N.
, p. 163 - 168 (2007/10/03)
The scope of aryl radical additions to the nitrogen of azomethines is described. Aryl, trifluoromethyl alkyl, and α,β-unsaturated ketimines engage in regioselective aryl-nitrogen bond formation via 5-exo cyclizations of an aryl radical to azomethine nitrogen. Selectivity for carbon-nitrogen over carbon-carbon bond formation is generally high (>95:5) and competes only with direct aryl radical reduction by stannane (0-10%). α-Ketoimines are a promising new class of carbon radical acceptors for which no competitive aryl radical reduction is observed. The reaction conditions are pH-neutral and are therefore among the mildest methods available for amination of an aromatic ring. The ketimines examined did not suffer from competitive reduction by stannane, offering an advantage over the use of diazo and azide functional groups as nitrogen sources for carbon radicals. The free radical-mediated aryl amination was sequenced with the O'Donnell phase transfer-catalyzed enantioselective alkylation strategy of glycinyl imine to provide either enantiomer of indoline α-amino acids with high ee. These new constrained phenyl alanine derivatives are now readily available for evaluation across a variety of applications.
Design of N-spiro C2-symmetric chiral quaternary ammonium bromides as novel chiral phase-transfer catalysts: Synthesis and application to practical asymmetric synthesis of α-amino acids
Ooi, Takashi,Kameda, Minoru,Maruoka, Keiji
, p. 5139 - 5151 (2007/10/03)
A series of C2-symmetric chiral quaternary ammonium bromides 10 and 11 have been designed as a new, purely synthetic chiral phase-transfer catalyst, and readily prepared from commercially available optically pure 1,1′-bi-2-naphthol as a basic c
