Synthesis of the (9S,18R)-seco acid of the leukocyte adhesion inhibitor cyclamenol A

A Stereocontrolled Total Synthesis of Lipoxin B4 and its Biological Activity as a Pro-Resolving Lipid Mediator of Neuroinflammation

Two stereocontrolled, efficient, and modular syntheses of eicosanoid lipoxin B4 (LXB₄ ) are reported. One features a stereoselective reduction followed by an asymmetric epoxidation sequence to set the vicinal diol stereocentres. The dienyne was installed via a one-pot Wittig olefination and base-mediated epoxide ring opening cascade. The other approach installed the diol through an asymmetric dihydroxylation reaction followed by a Horner-Wadsworth-Emmons olefination to afford the common dienyne intermediate. Finally, a Sonogashira coupling and an alkyne hydrosilylation/proto-desilylation protocol furnished LXB₄ in 25 % overall yield in just 10 steps. For the first time, LXB₄ has been fully characterized spectroscopically with its structure confirmed as previously reported. We have demonstrated that the synthesized LXB₄ showed similar biological activity to commercial sources in a cellular neuroprotection model. This synthetic route can be employed to synthesize large quantities of LXB₄ , enable synthesis of new analogs, and chemical probes for receptor and pathway characterization.

Microwave-Accelerated Solventless Sonogashira-Like Coupling Reaction of 1,1-Dibromo-1-Alkenes with Organic Halides on Nickel(0) Powder-Doped KF/Al2O3

Under solvent free and microwave irradiation reaction conditions, a Sonogashira-like coupling reaction of 1,1-dibromo-1-alkenes with organic halides on nickel(0) powder-doped KF/Al2O3 has been developed, which generates the corresponding alkynes in moderate to good yields.

Beta-amidoaldehydes via oxazoline hydroformylation

4-Substituted oxazolines, which are readily synthesized from naturally occurring alpha-amino acids, are converted efficiently and stereospecifically to beta-amidoaldehydes in the presence of synthesis gas and catalytic dicobalt octacarbonyl.