This manuscript describes an enantioselective synthesis of the naturally occurring alkaloid citrinadin B. The synthetic effort revealed an anomaly in the original structural assignment that has led to the proposal of a stereochemical revision. This revision is consistent with the structures previously reported for a closely related family of alkaloids, PF1270A-C. The synthesis is convergent and employs a stereoselective intermolecular nitrone cyloaddition reaction as a key step.
A solid-phase synthesis of Park nucleotide as well as lipids I and II analogues, which is applicable to the synthesis of a range of analogues, is described in this work. This technique allows highly functionalized macromolecules to be modularly labeled. Multiple steps are used in a short time (4 d) with a single purification step to synthesize the molecules by solid-phase synthesis.
The total synthesis of tunicamycin V is described. This strategy is based on the initial construction of tunicaminyluracil, which is regarded to play an important role in the observed biological activities. The key to the synthesis was a Mukaiyama aldol reaction followed by a furan-oxidation to construct the undecose skeleton, a [3,3] sigmatropic rearrangement of a cyanate, and a highly selective trehalose-type glycosylation.
This article describes the first total synthesis of luminamicin
using a strategy combining chemical degradation with synthesis. Chemical
degradation studies provided a sense of the inherent reactivity of
the natural product, and deconstruction of the molecule gave rise
to a key intermediate, which became the target for chemical synthesis.
The core structure of the southern part of luminamicin was constructed
by a 1,6-oxa-Michael reaction to form an oxa-bridged ring, followed
by coupling with a functionalized organolithium species. Modified
Shiina macrolactonization conditions forged the strained 10-membered
lactone containing a tri-substituted olefin. Diastereoselective α-oxidation
of the 10-membered lactone completed the center part to provide the
key intermediate. Inspired by the degradation study, an unprecedented
enol ether/maleic anhydride moiety was constructed with a one-pot
chlorosulfide coupling and thiol β-elimination sequence. Finally,
macrolactonization to the 14-membered ring in the presence of the
highly electrophilic maleic anhydride moiety was accomplished using
modified Mukaiyama reagents to complete the synthesis of luminamicin.
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