Stereoselectivity of the Benzannulation Reaction: Efficient Central-to-Axial Chirality Transfer
作者:Andrei V. Vorogushin、William D. Wulff、Hans-Jürgen Hansen
DOI:10.1021/ja0201505
日期:2002.6.1
High diastereoselectivity is observed in the preparation of configurationally stable allocolchicinoids 5 from Fischer carbene complexes 4 and 1-pentyne. The analogous reaction of complexes 8 gives 9 with moderate diastereoselectivity for the opposite atropisomer and this selectivity can be taken to high levels under thermodynamic conditions.
Convergent Synthesis of Fully Functionalized Ring C Allocolchicinoids. Benzannulation Approach
作者:Andrei V. Vorogushin、William D. Wulff、Hans-Jürgen Hansen
DOI:10.1021/ol0100881
日期:2001.8.1
[reaction: see text]. A novel convergent approach to fully functionalizedring C allocolchicinoids is developed which is based on the benzannulation reaction of Fischer carbene complexes with alkynes. The efficacy of this strategy was established with the conversion of bromide 1a (R1 = Me, R2 = H) to the biaryl phenol 3a (R = Me, R(L) = Pr, R(S) = H) via the carbene complex 2a. Bromide 1b (R1 = t-Bu
Central-to-axial chirality transfer in the benzannulation reaction of optically pure Fischer carbene complexes in the synthesis of allocolchicinoids
作者:Andrei V. Vorogushin、William D. Wulff、Hans-Jürgen Hansen
DOI:10.1016/j.tet.2007.10.115
日期:2008.1
of Fischer chromium carbene complexes with alkynes. The benzannulation reaction is employed to install the aromatic C-ring via the reaction of an alpha,beta-unsaturated carbene complex in which the carbene complex is attached to a seven-membered ring that is to become the B-ring of the allocolchicinoids. Two different regioisomeric series can be accessed depending on which position the carbene complex