5-exo-Selective asymmetric bromolactonization of stilbenecarboxylic acids catalyzed by phenol-bearing chiral thiourea.

We developed a novel thiourea Lewis-base catalyst with phenol moieties for the enantioselective 5-exo-bromolactonization of stilbenecarboxylic acids to afford chiral 3-substituted phthalides. The phenol moieties are crucial for the enantio- and regio-selectivity.

Total synthesis of 1,4a-di-epi-ent-pancratistatin, exemplifying a stereodivergent approach to pancratistatin isomers.

The total synthesis of 1,4a-di-epi-ent-pancratistatin, a novel stereoisomer of the anti-tumor Amaryllidaceae alkaloid pancratistatin, was achieved in 14 steps starting from D-mannitol. The construction of the pancratistatin skeleton involved conjugate addition of organocuprate to a nitrosoolefin, which was generated in situ from inosose oxime. This was followed by stereoselective reduction of the oxime to an amine and site-selective formylation. Biological evaluations revealed that the newly synthesized compounds exhibit cytotoxicity toward cancer cells and significant ferroptosis inhibitory activity. These compounds constitute a promising small-molecule library for the development of potent bioactive agents.