Efficient Aryl Migration from an Aryl Ether to a Carboxylic Acid Group To Form an Ester by Visible-Light Photoredox Catalysis
We have developed a highly efficient aryl migration from an aryl ether to a carboxylic acid group through retro-Smiles rearrangement by visible-light photoredox catalysis at ambient temperature. Transition metals and a stoichiometric oxidant and base are avoided in the transformation. Inspired by the high efficiency of this transformation and the fundamental importance of C?O bond cleavage, we developed a novel approach to the C?O cleavage of a biaryl ether to form two phenolic compounds, as demonstrated by a one-pot, two-step gram-scale reaction under mild conditions. The aryl migration exhibits broad scope and can be applied to the synthesis of pharmaceutical compounds, such as guacetisal. Primary mechanistic studies indicate that the catalytic cycle occurs by a reductive quenching pathway.
Wang, Shao-Feng,Cao, Xiao-Ping,Li, Yang
p. 13809 - 13813
(2017/10/24)
Ortho-selectivity in SNAr substitutions of 2,4-dihaloaromatic compounds. Reactions with anionic nucleophiles
The nucleophilic addition of organic anions to aromatic compounds with halogens positioned both ortho and para to activating groups was studied in a variety of solvents. Substrates showed strong preferences for ortho substitution in most cases. Evidence is presented for activating group-dependent coordination, which contributes to very high ortho-selectivity in nonpolar solvents. This also drives the overall reaction rate in these solvents, and is of close to the same magnitude of rate increase derived from polar solvents. para-Products are maximized by using crown ethers in protic solvents. Solvent effects overall are very different from corresponding reactions with amine nucleophiles due primarily to the different charges present in the transition states, and to solvation of the nucleophile.
Wendt, Michael D.,Kunzer, Aaron R.
scheme or table
p. 3041 - 3044
(2010/07/18)
Tricyclic delta-opioid modulators
The invention is directed to delta opioid receptor modulators. More specifically, the invention relates to tricyclic δ-opioid modulators. Pharmaceutical and veterinary compositions and methods of treating mild to severe pain and various diseases using com
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Page/Page column 29-30
(2008/06/13)
TRICYCLIC DELTA OPIOID MODULATORS
The invention is directed to delta opioid receptor modulators. More specifically, the invention relates to tricyclic δ-opioid modulators. Pharmaceutical and veterinary compositions and methods of treating mild to severe pain and various diseases using compounds of the invention are also described.
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Page 42-43
(2008/06/13)
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