Regio- and stereoselectivity of additions of organometallics to - and -tricyclo[5.2.1.02,6]deca-4,8-dien-3-ones
摘要:
The regio- and stereoselectivity of the addition of selected organometallics to endo- and exo-tricyclodecadienones 12, 18 and 21 are described. RLi and R(2)Culi add with complete 1,2- and 1,4-regioselectivity, respectively, the additions of RMgX and RMgX/CuX are only slightly less selective. Additions to 12 and 21 occur from the convex exo-face only, irrespective of the nature of both reagent and substrate. In contrast, organometallic species add from both the concave and the convex face to tricyclic ester 18, with a selectivity that depends on the type of organometallic reagent. The observed stereoselectivities of the additions are rationalized by invoking steric control by the C-8-C-9 ethylene bridge in 12, by the C-10 methylene bridge in 21 and by both the C-8-C-9 ethylene bridge and the exo-ester function at C-2 in tricyclic ester 18.
A practical and environmentally friendly method for oxidative rearrangement of five- and six-membered cyclic tertiary allylic alcohols to beta-disubstituted alpha,beta-unsaturated ketones by the IBX/DMSO reagent system is described. Several conventional protecting groups (e.g., Ac, MOM, and TBDPS) are compatible under the reaction conditions prescribed.
Enantioconvergent route to α-cuparenone from dicyclopentadiene
作者:Seiichi Takano、Kohei Inomata、Kunio Ogasawara
DOI:10.1039/c39890000271
日期:——
A formal enantioconvergentroute to α-cuparenonefromdicyclopentadiene has been devised by employing lipase catalysed kinetic hydrolysis as the key step.
Nucleophilic additions to tricyclodecadienone epoxides. The Payne rearrangement of α,β-epoxycyclopentanols contained in a rigid tricyclic system
作者:Paul P.M.A. Dols、Esther G. Arnouts、Johannes Rohaan、Antonius J.H. Klunder、Binne Zwanenburg
DOI:10.1016/s0040-4020(01)87027-7
日期:1994.3
conditions and type of organometallicreagent. Reduction of 6 and 7 with lithiumaluminumhydride yields the same tricyclic trans-1,3-diols 20. It is shown that reduction of 6 with lithiumaluminumhydride proceeds via slow Payne rearrangement of its alkoxide 11b to inverted alkoxide 12b, followed by rapid addition of hydride to C4 from the exo-face.