Total synthesis of cortistatins A and J.

This paper describes the details of our synthetic studies on the marine steroidal alkaloids cortistatins A and J. The key features of our strategy include (i) an efficient Knoevenagel/electrocyclic strategy to couple the diketone and the CD-ring fragment, (ii) a chemoselective radical cyclization to construct the oxabicyclo[3.2.

Brønsted acid-catalyzed cascade cycloisomerization of enynes via acetylene cations and sp3-hybridized C-H bond activation.

A novel Brønsted acid-catalyzed cascade cycloisomerization of cyclic and acyclic enynes via acetylene cation cyclization followed by cleavage of the entirely inactive C(sp(3))-H bond is described. The reaction proceeds efficiently under mild conditions to afford various tri- and bicyclic compounds in good to high yields.