Total synthesis of forskolin — Part I

Copper‐Catalyzed Asymmetric Conjugate Addition of Trialkylaluminium Reagents to Trisubstituted Enones: Construction of Chiral Quaternary Centers

“…The remaining compounds were prepared according to general procedures (see Experimental Section). [11][12][13][14] Abstract: Me 3 Al, Et 3 Al, and vinylalane species undergo enantioselective conjugate addition to a wide range of 2-or 3-substituted enones (cyclopent-2enones, cyclohex-2-enones, 3-methyl cyclohept-2-enone) in the presence of catalytic amount of copper salt (copper thiophene carboxylate, 4 ]BF 4 or [CuOTf] 2 ·C 6 H 6 ) and tropos-phosphoramidite-based ligand. Thus, chiral quaternary centers can be built, with up to 98 % ee after rigorous optimization of experimental condi-tions.…”

Absolute stereochemistries and total synthesis of (+)-arisugacins A and B, potent, orally bioactive and selective inhibitors of acetylcholinesterase

“…The cyclization step should proceed with the requisite geometry at the BC ring fusion, which is controlled by the steric effect of the C-12b angular methyl group. The known lactone 13, an intermediate for the synthesis of forskolin, 29 would then lead to lactol 12.…”

The Chemistry of Bioactive Diterpenes

“…Lett and collaborators [103] have accomplished a total synthesis of forskolin and this is described in Scheme 12.…”