Spinal anaesthesia in obstetrics.

This article provides a comprehensive review of the technique, drugs of choice, and potential side effects and complications associated with the drugs used and the single-shot spinal anaesthesia (SSS) technique for caesarean delivery. Although neuraxial analgesia and anaesthesia are generally considered safe, all interventions come with potential adverse effects. As such, the practice of obstetric anaesthesia has evolved to minimize such risks.

Donor-Acceptor Aminocyclobutane Monoesters: Synthesis and Silylium-Catalyzed (4+2) Annulation with Indoles.

A convenient one-step synthesis of β-aminocyclobutane monoesters starting from commercially available reagents is reported. The obtained strained rings undergo (4+2) dearomative annulation with indole partners using silylium catalysis. This organocatalyzed annulation provided tricyclic indolines with four new stereocenters in up to quantitative yield and >95 : 5 diastereoselectivity and can proceed both intra- and intermolecularly.

Enantioselective Total Synthesis of (+)-Eucophylline.

The total enantioselective synthesis of (+)-eucophylline 1 was achieved using as a key-structural motif a chiral piperidinone bearing the natural product all-carbon quaternary stereocenter. The elaboration of the latter is based on two strategies relying on the free-radical carbo-cyanation and sulfonyl-cyanation respectively of enantiopure substituted cyclopropenes and cyclobutenes. Co- or Ni-boride reduction of the nitrile functional group along with the cyclopropane and cyclobutane ring-opening then led to the formation of the chiral piperidinone ring.

Catalytic (3 + 2) annulation of donor-acceptor aminocyclopropane monoesters and indoles.

The efficient catalytic activation of donor-acceptor aminocyclopropanes lacking the commonly used diester acceptor is reported here in a (3 + 2) dearomative annulation with indoles. Bench-stable tosyl-protected aminocyclopropyl esters were converted into cycloadducts in 46-95% yields and up to 95 : 5 diastereomeric ratio using catalytic amounts of triethylsilyl triflimide. Tricyclic indoline frameworks containing four stereogenic centers including all-carbon quaternary centers were obtained.

Catalytic Enantioselective Ring-Opening Reactions of Cyclopropanes.

This review describes the development of enantioselective methods for the ring opening of cyclopropanes. Both approaches based on the reaction of nonchiral cyclopropanes and (dynamic) kinetic resolutions and asymmetric transformations of chiral substrates are presented. The review is organized according to substrate classes, starting by the more mature field of donor-acceptor cyclopropanes.

-Anisaldehyde-Photosensitized Sulfonylcyanation of Chiral Cyclobutenes: Enantioselective Access to Cyclic and Acyclic Systems Bearing All-Carbon Quaternary Stereocenters.

The photosensitized -anisaldehyde-mediated addition of sulfonylcyanides onto the π-system of cyclobutenes is shown to afford highly functionalized cyclobutanes in high yields and diastereocontrol. The homochiral cyclobutene precursors are accessible on multigram scale in two steps through an asymmetric [2 + 2] cycloaddition/vinyl thioether reduction sequence. The enantiopure cyclobutylnitriles can be elaborated further through SmI-mediated ring opening or converted into new enantiopure cyclobutenes through base-mediated sulfone elimination.

Eosin-Mediated Alkylsulfonyl Cyanation of Olefins.

Eosin-Y (EY)-mediated alkylsulfonyl cyanation of olefins was shown to afford alkylsulfonyl nitriles in good yields. On the basis of transient absorption spectroscopy, the reaction was shown to proceed via photoinduced electron transfer from EY* to an O-cyanated derivative of the photocatalyst, formed in situ, with generation of the corresponding sulfinate that is oxidized by EY into a sulfonyl radical. Addition of the latter on the olefin, followed by a radical cyano group transfer, then furnished the nitrile along with a RSO radical sustaining the radical chain.

Free-Radical Carbocyanation of Olefins.

The free-radical three-component carbocyanation of electron-rich olefins was investigated with p-tosyl cyanide as cyanide source. The scope and limitations of the process were established by varying the nature of the alkene and radical precursor. Carbocyanation of chiral allylsilanes was shown to occur with high diastereocontrol, leading to syn β-silyl nitriles.