Although
greener and faster access to fine chemicals and APIs is
highly desirable, there are currently no synthetic methodologies which
undergo reaction completions within a few seconds to minutes in water
under benchtop laboratory conditions. Here, we report a methodology
that allows the instantaneous formation of ligated ultrasmall Pd nanoparticles
in the hydrophobic pockets of benign cellulose derivative (HPMC) for
chemical reactions to proceed very fast in water under mild reaction
conditions. Unprecedented short reaction times were exemplified for
the Buchwald–Hartwig aminations. In addition, very short reaction
times of less than a minute were also demonstrated for the amide couplings,
which is the most utilized reaction type in the pharmaceutical industry.
Hydrazines form a new family of low molecular-weight reducing agents for diazonium salts. Using only small amounts of hydrazine catalyst, the coupling of diazonium salts to a variety of reactive partners has been achieved, without the requirement for either metal adjuvants or irradiation with visible or ultraviolet light. The generality of the concept proposed herein as well as its advantages in the preparative scale is outlined and discussed.
Last‐minute deal: A direct lactonisation of ethers and alcohols onto amides that proceeds at room temperature under mild conditions is reported (see scheme). This allows the effective saving of up to two unproductive, sequential deprotection operations in synthetic sequences. Mechanistic studies are described, and a new “amide strategy” that exploits the dual robustness/late‐stage selective activation properties of this functional group is outlined.
We report a novel approach to the classical natural product quinine that is based on two stereoselective key steps, namely a C−H activation and an aldol reaction, to unite the two heterocyclic moieties of the target molecule. This straightforward and flexible strategy enables a concise synthesis of natural (−)‐quinine, the first synthesis of unnatural (+)‐quinine, and also provides access to unprecedented C3‐aryl analogues, which were prepared in only six steps. We additionally demonstrate that these structural analogues exhibit improved antimalarial activity compared with (−)‐quinine both in vitro and in mice infected with Plasmodium berghei.
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