Mild Ti<sup>III</sup>- and Mn/Zr<sup>IV</sup>-Catalytic Reductive Coupling of Allylic
Halides: Efficient Synthesis of Symmetric Terpenes<sup>†</sup>
Alejandro F. Barrero
M. Mar Herrador
José F. Quílez del Moral
Pilar Arteaga
Jesús F. Arteaga
Horacio R. Diéguez
Elena M. Sánchez
10.1021/jo062630a.s001
https://acs.figshare.com/articles/journal_contribution/Mild_Ti_sup_III_sup_and_Mn_Zr_sup_IV_sup_Catalytic_Reductive_Coupling_of_Allylic_Halides_Efficient_Synthesis_of_Symmetric_Terpenes_sup_sup_/3013114
Two new efficient methods for the regioselective homocoupling of allylic halides using either catalytic
Ti<sup>III</sup> or the combination Mn/Zr<sup>IV</sup> catalyst have been developed. The regio- and stereoselectivity of the
process proved to increase significantly when the Mn/Zr<sup>IV</sup> catalyst is used as the coupling reagent and
when cyclic substituted allylic halides are used as substrates. The use of Lewis acids such as collidine
hydrochloride allowed the quantity of catalyst to be lowered up to 0.05 equiv. We have proved the
utility of these protocols with the synthesis of different terpenoids such as (+)-β-onoceradiene (<b>1</b>), (+)-β-onocerine (<b>2</b>), squalene (<b>5</b>), and advanced key-intermediates in the syntheses of (+)-cymbodiacetal (<b>3</b>)
and dimeric <i>ent</i>-kauranoids as xindongnin M (<b>4a</b>).
2007-04-13 00:00:00
allylic halides
Mn
TiIII
catalyst