Sulfoximines
and sulfonimidamides are promising compounds for medicinal
and agrochemistry. As monoaza analogues of sulfones and sulfonamides,
respectively, they combine good physicochemical properties, high stability,
and the ability to build complexity from a three-dimensional core.
However, a lack of quick and efficient methods to prepare these compounds
has hindered their uptake in molecule discovery programmes. Herein,
we describe a unified, one-pot approach to both sulfoximines and sulfonimidamides,
which exploits the high electrophilicity of sulfinyl nitrenes. We
generate these rare reactive intermediates from a novel sulfinylhydroxylamine
(R–O–N=S=O) reagent through an N–O bond fragmentation
process. Combining sulfinyl nitrenes with carbon and nitrogen nucleophiles
enables the synthesis of sulfoximines and sulfonimidamides in a reaction
time of just 15 min. Alkyl, (hetero)aryl, and alkenyl organometallic
reagents can all be used as the first or second component in the reaction,
while primary and secondary amines, and anilines, all react with high
efficiency as the second nucleophile. The tolerance of the reaction
to steric and electronic factors has allowed for the synthesis of
the most diverse set of sulfoximines and sulfonimidamides yet described.
Experimental and computational investigations support the intermediacy
of sulfinyl nitrenes, with nitrene formation proceeding via a transient
triplet intermediate before reaching a planar singlet species.
Photo-mediated 6p cyclization is avaluable method for the formation of fused heterocyclic systems.H ere we demonstrate that irradiation of cyclic 2-aryloxyketones with blue LED light in the presence of an Ir III complex leads to efficient and high yielding arylation across ap anoply of substrates by energy transfer.2 -Arylthioketones and 2-arylaminoketones also cyclizee ffectively under these conditions. Quantum calculation demonstrates that the reaction proceeds via conrotatory ring closure in the triplet excited state. Subsequent suprafacial 1,4-hydrogen shift and epimerization leads to the observed cis-fused products.
In the past two decades, alkene metathesis has risen in prominence to become a significant synthetic strategy for alkene formation. Many total syntheses of natural products have used this transformation. We review the use, from 2003 to 2015, of ring-closing alkene metathesis (RCM) for the generation of dihydrofurans or -pyrans in natural product synthesis. The strategies used to assemble the RCM precursors and the subsequent use of the newly formed unsaturation will also be highlighted and placed in context.
Photo-mediated 6p cyclization is avaluable method for the formation of fused heterocyclic systems.H ere we demonstrate that irradiation of cyclic 2-aryloxyketones with blue LED light in the presence of an Ir III complex leads to efficient and high yielding arylation across ap anoply of substrates by energy transfer.2 -Arylthioketones and 2-arylaminoketones also cyclizee ffectively under these conditions. Quantum calculation demonstrates that the reaction proceeds via conrotatory ring closure in the triplet excited state. Subsequent suprafacial 1,4-hydrogen shift and epimerization leads to the observed cis-fused products.
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