A direct acyl radical addition to 2 H-indazoles has been achieved for the first time, where the less-aromatic quinonoid 2 H-indazoles readily accepted radical species to the C-3 position. Motivated by the lack of direct acylation strategy for 2 H-indazoles, the current method utilizes the radical acceptability of 2 H-indazoles, discovering an ambient temperature reaction to provide facile access to a diverse array of 3-acyl-2 H-indazoles with three points of structural diversification in 25%-83% yields.
An ortho-naphthoquinone-catalyzed oxidative deamination reaction has been developed where the molecular oxygen
and water serve as the sole oxidant and nucleophile. The current aerobic deamination reaction proceeds via the ketimine formation
between ortho-naphthoquinones and amines followed
by the prototropic rearrangement and hydrolysis by water, representing
a biomimetic oxidative deamination of amine species
in the human body by the liver and kidneys. The compatibility of ortho-naphthoquinone organocatalysts with molecular oxygen
and water opens up a new biomimetic catalyst system that can function
as versatile deaminases for a variety of amine-containing molecules
such as amino acids and DNA nuclear bases.
A convenient visible-light
photoredox catalysis has been developed
for the synthesis of thioesters from two readily available starting
materials: acid chlorides and sodium sulfinates. The facile generation
of acyl radical species under the visible light photoredox conditions
allows the formation of thiyl radical species from sodium sulfinates
via multiple single electron transfer reactions, where the final acyl
radical-thiyl radical coupling has been accomplished. The direct radical–radical
coupling strategy offers a mild and controlled photochemical approach
to important synthetic building blocks such as thioesters.
The first total synthesis of (S)-6-(2,9-dihydroxynonyl)-4-hydroxy-3-methyl-2H-pyran-2-one, 4-hydroxy-3-methyl-6-((2S,4R)-2,4,11-trihydroxyundecyl)-2H-pyran-2-one, and its unnatural 2R,4R-isomer starting from commercially available 1,8-octanediol is described. The synthesis led to the revision of the proposed structural assignment of the natural product as (R)-6-(2,9-dihydroxynonyl)-4-hydroxy-3-methyl-2H-pyran-2-one. The key steps include chiral auxiliary mediated asymmetric acetate aldol reaction, dianion addition, and base mediated cyclization to form an α-pyrone ring.
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