[Thu. 6 Apr. 2017] Prof. Rong-Jie Chein/Institute of Chemistry, Academia Sinica, Nankang, Taipei, Taiwan

“Hydroxy/Amine-Directed Ortho-Alkylation and Its Application

in Total Synthesis of Panduratin D”

Hydroxyl/amine-directed ortho-nucleophilic acyl alkylations of N,N-diethylarylamides have been developed using a simple reagent combination of LDA and chlorosilane. The

transformations involve: 1) a complex-induced proximity effect (CIPE) in the deprotonation step, 2) an intramolecular Peterson-type reaction of the resulting α-silyl carbanion with the amide group, and 3) fission of the final β-oxygenated/nitrogenated silyl intermediate. The study of the mechanism, as well as the application of the protocol to an anionic Hellwinkel-Snieckus-Fries rearrangement, a series of highly efficient functional group transformations, and a total synthesis of Panduratin D, a cytotoxic natural product against pancreatic cancer cells, are reported.

[1] H.-J. Lo, C.-Y. Lin, M.-C. Tseng, R.-J. Chein, Angew. Chem. Int. Ed. 2014, 53, 9026.

[2] C.-Y. Lin, M.-C. Tseng, R.-J. Chein, Synlett: SYNPACTS, 2014, 25, 2827–2830.

[3] I. F. Yu, R.-J. Chein, to be submitted.

[4] S. R. Bavikar, R.-J. Chein, to be submitted.

“Chiral Tetrahydrothiophene Ligands in Asymmetric Catalysis”

Chiral sulfur ligands are becoming a versatile tool in organic chemistry due to the

blossomed development achieved in the past years. This presentation describes an

expeditious and efficient preparation of enantiopure (thiolan-2-yl)diarylmethanols and

the applications of their derivatives to catalytic and asymmetric Corey-Chaykovsky

epoxidation,1 the imino Corey-Chaykovsky aziridination,2,3 as well as the first oxathiaborenium catalyzed asymmetric Diels-Alder reaction.4,5

Reference

1. Wu, H.-Y.; Chang, C.-W.; Chein, R.-J. J. Org. Chem. 2013, 78, 5788-5793.

2. Huang, M.-T.; H.-Y. Wu; Chein, R.-J. Chem. Commun. 2014, 50, 1101-1103.

3. Wang, S.-H.; Chein, R.-J. Tetrahedron, 2016, 72, 2607-2615.

4. Kumar, S. N.; Yu, I. F.; Chein, R.-J. Org. Lett. 2017, 19, 22-25. (Highlighted by C&EN 2017, 95(1), 9).

5. Tsai, M.-L.; Chein, R.-J. to be submitted.

Prof. Rong-Jie Chein

Institute of Chemistry, Academia Sinica, Nankang, Taipei, Taiwan