Stereoselective cyclizations mediated by functionalized organomagnesium reagents and catalyzed by cobalt or copper salts
作者:Florian F. Kneisel、Yasunari Monguchi、Kolja M. Knapp、Hendrik Zipse、Paul Knochel
DOI:10.1016/s0040-4039(02)00839-0
日期:2002.7
with i-PrMgCl allows a mild preparation of functionalized arylmagnesium compounds bearing a leaving group in the molecule. With the appropriate transition-metal catalyst (a copper or cobalt salt), cyclization reactions occur leading to five- or six-membered ring systems in good yields.
A New Approach to Dihydrobenzofurans and Dihydrobenzopyrans (Chromans) Based on the Intramolecular Trapping by Alcohols of Benzynes Generated from 7-Substituted-1-aminobenzotriazoles
作者:Michael A Birkett、David W Knight、Paul B Little、Michael B Mitchell
DOI:10.1016/s0040-4020(00)00021-1
日期:2000.2
1-Aminobenzotriazoles 9 having 7-hydroxyalkyl substituents are efficiently converted into the corresponding benzynes 4 when treated with N-iodosuccinimide which then undergo highly efficient intramoleculartrapping by the pendanthydroxylgroups leading to dihydrobenzofurans 24–26 and dihydrobenzopyrans (chromans) 27, with incorporation of a synthetically useful iodine atom adjacent to the new ether bond, which allows