A flexible route to immunosuppressive agent FR252921. Asymmetric total synthesis of its (13R,14R,19R)-isomer

Synthesis of Polyene Bioactive Natural Products: FR252921 and Vitamin A

A formal synthesis of FR252921, a potent macrocyclic immunosuppressive agent, and a six-step synthesis of vitamin A have been demonstrated. The application of a ruthenium-catalyzed step-economic and environmentally benign strategy for the highly stereo- and chemoselective construction of valuable polyene motifs of FR252921 and vitamin A highlights the syntheses. The key features for the synthesis FR252921 include preparation of the triene moiety followed by two consecutive peptide couplings of the three fragments.

A Domino 10-Step Total Synthesis of FR252921 and Its Analogues, Complex Macrocyclic Immunosuppressants

FR252921, FR252922, and FR256523 are a family of potent macrocyclic polyene immunosuppressive agents with a novel mode of action. However, the lack of an efficient and flexible synthesis has hindered further biological studies, mostly due to the fact that the natural products appear to be kinetic isomers regarding the triene moiety. Herein, we report the development and application of an unprecedented, unique domino Suzuki–Miyaura/4π-electrocyclic ring-opening macrocyclization, resulting in a concise, unified, and stereoselective synthetic route to these complex targets in only 10 steps. This in turn enables ready access to a range of unnatural analogues, among which several compounds showed inhibition of T-lymphocyte proliferation at levels equal or superior to those of the natural products themselves.

An enantioselective synthesis of the C3-C21 segment of the macrolide immunosuppressive agent FR252921

An enantioselective synthesis of the C3-C21 segment of the novel immunosuppressant FR252921 is described. The C12 and C13 stereogenic centers were constructed by a non-aldol process utilizing optically active 4-phenylbutyrolactone. The C18 stereogenic center was installed using Braun's highly diastereoselective acetate aldol reaction. Other key steps involved Curtius rearrangement and Horner-Wadsworth-Emmons olefination reactions.

Synthesis of two bioactive natural products: FR252921 and pseudotrienic acid B

Concise and highly convergent syntheses of the immunosuppressive agent FR252921 and the related antimicrobial natural product pseudotrienic acid B were achieved from a common intermediate by using optically active titanium complexes to control the configuration of the stereogenic centers, a highly stereo- and regioselective cross-metathesis to generate the triene moieties, and a Stille cross-coupling to install the dienic units.

Expeditious Enyne Construction from Alkynes via Oxidative Pd(II) Catalyzed Heck-Type Coupling

The enyne, ubiquitous in natural products, can be a challenge to generate since these moieties require many synthetic transformations to assemble them. We developed a simpler protocol to construct enynes while we found that this oxidative reaction was tolerant in substrate scope. In addition, the utility of this reaction was demonstrated through the attempt in synthesizing antifungal agent Lamisi.