posted on 2014-11-07, 00:00authored byMatthew
R. Luderer, Michael J. Mealy, William F. Bailey
Concise
syntheses of the sesquiterpenes (R)-(+)-cuparene
and (R)-(+)-herbertene by asymmetric cyclization
of achiral olefinic alkyllithium precursors in the presence of (−)-sparteine
are reported. The quaternary stereogenic center in each product is
set at the final step of the synthesis by enantioselective (er = 61:39)
5-exo ring closure.