Total synthesis and preliminary biological evaluation of cis-solamin isomers.

An efficient total synthesis of cis-solamin (1) has been achieved in 21% overall yield and with a longest linear sequence of just 11 steps from aldehyde 8. A key feature of the approach was the use of asymmetric permanganate-promoted oxidative cyclization to introduce four of the five required stereocenters in a single step. The use of robust and chemoselective methodology meant that the use of protecting groups could be avoided during the assembly of cis-solamin (1) from the three fragments 23, 6, and 4. The methodology was also applied to the synthesis of three further cis-solamin isomers 2, ent-1, and ent-2. Cytotoxicity and hemolytic properties of cis-solamin isomers and synthetic intermediates are reported.