314021-31-3Relevant academic research and scientific papers
Photochemical generation of acyl and carbamoyl radicals using a nucleophilic organic catalyst: Applications and mechanism thereof
Balletti, Matteo,De Pedro Beato, Eduardo,Mazzarella, Daniele,Melchiorre, Paolo
, p. 6312 - 6324 (2020/08/24)
We detail a strategy that uses a commercially available nucleophilic organic catalyst to generate acyl and carbamoyl radicals upon activation of the corresponding chlorides and anhydrides via a nucleophilic acyl substitution path. The resulting nucleophilic radicals are then intercepted by a variety of electron-poor olefins in a Giese-type addition process. The chemistry requires low-energy photons (blue LEDs) to activate acyl and carbamoyl radical precursors, which, due to their high reduction potential, are not readily prone to redox-based activation mechanisms. To elucidate the key mechanistic aspects of this catalytic photochemical radical generation strategy, we used a combination of transient absorption spectroscopy investigations, electrochemical studies, quantum yield measurements, and the characterization of key intermediates. We identified a variety of off-the-cycle intermediates that engage in a light-regulated equilibrium with reactive radicals. These regulated equilibriums cooperate to control the overall concentrations of the radicals, contributing to the efficiency of the overall catalytic process and facilitating the turnover of the catalyst. This journal is
Studies Directed toward the Total Synthesis of Azaspiracid: Stereoselective Construction of C1-C12, C13-C19, and C21-C25 Fragments
Carter, Rich G.,Weldon, David J.
, p. 3913 - 3916 (2007/10/03)
equation presented The efficient entry to the C1-C12, C13-C19, and C21-C25 fragments of azaspiracid is outlined. The C1-C12 portion is constructed using a key asymmetric allenyl borane addition to the corresponding α,β-unsaturated aldehyde. The synthesis of the C13-C19 portion utilizes an Evans asymmetric alkylation followed by Sharpless asymmetric dihydroxylation. In addition, a novel solution to the mismatched effects of a neighboring chiral oxazolidinone during a Sharpless dihydroxylation is detailed.
