Progress toward the Total Synthesis of Lymphostins: Preparation of a Functionalized Tetrahydropyrrolo[4,3,2-de]quinoline and Unusual Oxidative Dimerization

Concise Synthesis and Biological Evaluation of the Pyrrolo[4,3,2-de]quinoline Core of the Lymphostin Family

The efficient synthesis of the pyrrolo[4,3,2-de]quinoline core of the lymphostin family (compound 1) has been accomplished in 7 steps and 18.6% overall yield, providing an efficient method for the total synthesis and structural modification of the lymphostin family. Compound 1 showed potent inhibitory activities against PI3K/mTOR in the nanomolar range and activity against human colorectal cancer cell lines comparable to that of oxaliplatin, which could be recognized as a novel lead compound for cancer therapy.

Assembly of spirocyclic pyrazolone-pyrrolo[4,3,2-de]quinoline skeleton via cascade [1,5] hydride transfer/cyclization by C(sp3)-H functionalization

Herein, a highly efficient, scalable, and cascade [1,5] hydride transfer/cyclization method for constructing unique spirocyclic pyrazolone-pyrrolo[4,3,2-de]quinoline structures via C(sp3)-H functionalization is achieved, using pyrazolones and oxindoles attached to C4 amines. This strategy represents a limited approach utilizing C-H activation to construct spirocyclic pyrazolone scaffolds with moderate to excellent reaction performance.

Concise catalytic asymmetric synthesis of (R)-4-amino Uhle's ketone

A practical and asymmetric synthesis of (R)-4-amino-5-oxo-1,3,4,5-tetrahydrobenz[cd]indole, an enantiopure framework shared by most ergot alkaloids, was accomplished. Our method involves a Rh(i)-catalyzed 6-exo-trig intramolecular cyclization of an appropriate 4-pinacolboronic ester d-tryptophan aldehyde followed by the oxidation of the resulting secondary benzylic alcohol with a Cu(i)-ABNO catalyst and final deprotection under acidic conditions. This new procedure offers significant advantages over previous synthetic approaches, including brevity, mild reaction conditions, preservation of chiral integrity, and high overall yield and avoids the use of stoichiometric amounts of strongly basic and pyrophoric organometallic reagents.

Regioselective remote C5 cyanoalkoxylation and cyanoalkylation of 8-aminoquinolines with azobisisobutyronitrile

The efficient regioselective C-H cyanoalkoxylation and cyanoalkylation of 8-aminoquinoline derivatives at the C5 position have been achieved under O2 and N2 atmospheres, respectively. Using 2,2'-azobisisobutyronitrile (AIBN) as a radical precursor, the protocols afforded the corresponding products in moderate to good yields with broad substrate generality through Cu(OAc)2 or NiSO4 catalysis. Furthermore, the single electron transfer (SET) mechanism was proposed via a radical coupling pathway.