RESUMEN
Since its discovery, the Julia-Kocienski olefination reaction has over past 30 years become one of the key C-C connective methods that is used in late-stage natural product synthesis. The reaction proceeds under mild reaction conditions, with a wide substrate scope and functional group tolerance range and with high (E) selectivity. In this focused review, we discuss the reaction from a mechanistic point of view and disclose key features that play an important role in reaction selectivity. Finally, the mechanistic aspects of the newly developed modification of the Julia-Kocienski reaction, which allows the formation of both (E) and (Z) olefins from the same reaction partners, are discussed.
RESUMEN
The enantioselective addition of isoxazolidin-5-ones to the ß-carbon of allenoates has been carried out by using a novel spirobiindane-based quaternary ammonium salt catalyst. This protocol, which proceeds under classical liquid-solid phase-transfer conditions, gives access to unprecedented highly functionalized ß2,2-amino acid derivatives with good enantioselectivities and in high yields, and further manipulations of these products have been carried out as well.
RESUMEN
Heteroaryl sulfonamides are important structural motifs in the medicinal and agrochemical industries. However, their synthesis often relies on the use of heteroaryl sulfonyl chlorides, which are unstable and toxic reagents. Herein, we report a protocol that allows direct oxidative coupling of heteroaryl thiols and primary amines, readily available and inexpensive commodity chemicals. The transformation proceeds under mild reaction conditions and yields the desired N-alkylated sulfonamides in good yields. N-alkyl heteroaryl sulfonamides can be further transformed using a microwave-promoted Fukuyama-Mitsunobu reaction to N,N-dialkyl heteroaryl sulfonamides. The developed protocols thus enable the preparation of previously difficult to prepare sulfonamides (toxic reagents, harsh conditions, and low yields) under mild conditions.
