Catalytic Asymmetric Total Syntheses of (+)-Α-cuparenone, (+)-Cuparene and (+)-Herbertene

A general catalytic asymmetric route to either enantiomers of sesquiterpenes, cuparenes (1-2) and herbertenes (8-9) is disclosed from commercially available 3 -methyl cyclopenten-2-one. Following a catalytic enantioselective addition of arylboronic acids to enone 15, compounds 14a -b with all carbon quaternary stereocenters are synthesized in up to 90% ee in the presence of Pd(II)-PyOx (pyridine oxazoline). Compounds 14a -b are used as precursors for the asymmetric total syntheses of (+)-cuparene (la) (35% overall yield in 3 steps), a-(+)-cuparenone (lb) (56% overall yield in 2 steps), and (+)-herbertene (8a) (34% overall yield in 3 steps). (C) 2020 Elsevier Ltd. All rights reserved.