Reductive coupling of terpenic allylic halides catalyzed by Cp2TiCl: a short and efficient asymmetric synthesis of onocerane triterpenes.
[reaction: see text] Titanocene chloride catalyzes the regioselective alpha,alpha'-homocoupling of terpenic allylic halides. This process has been employed in the short and effective synthesis of terpenoids such as beta-onoceradiene (1), beta-onocerin (2), and squalene (3). Evidence is presented for eta1-allyltitanium species being involved in the coupling.
Barrero
Alejandro F
AF
Department of Organic Chemistry, Institute of Biotechnology, University of Granada, Avenida Fuentenueva, 18071 Granada, Spain. afbarre@goliat.ugr.es
Herrador
M Mar
MM
Quílez del Moral
José F
JF
Arteaga
Pilar
P
Arteaga
Jesús F
JF
Piedra
María
M
Sánchez
Elena M
EM
D000498:Allyl Compounds / Q000737:chemistry; D002384:Catalysis; D006846:Hydrocarbons, Halogenated / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D013729:Terpenes / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*; D014315:Triterpenes / Q000138:chemical synthesis* / Q000737:chemistry
D000498:Allyl Compounds; D006846:Hydrocarbons, Halogenated; D009942:Organometallic Compounds; D013729:Terpenes; D014315:Triterpenes; C406884:titanocene; D014025:Titanium