A route to ortho-substituted benzyne precursors by deprotonation of 7-methyl-1-aminobenzotriazole derivatives
作者:Michael A. Birkett、David W. Knight、Michael B. Mitchell
DOI:10.1016/s0040-4039(00)91835-5
日期:1993.10
obenzotriazole 6 using nBuLi-TMEDA-THF [−78°C - > 0°C] results in an essentially quantitative conversion to the dianionic intermediate 7. Trapping at the carbon-centred anion occurs selectively under suitable conditions with alkylating agents, aldehydes and ketones to give good to excellent yields of the 7-substituted-1-aminobenzotriazoles 8–15, precursors of -substituted benzynes.
A new approach to dihydrobenzofurans by intramolecular trapping of benzynes by hydroxyl functions
作者:Michael A. Birkett、David W. Knight、Michael B. Mitchell
DOI:10.1016/s0040-4039(00)91836-7
日期:1993.10
The adducts 3, derived from condensations of the 1-aminobenzotriazole dianion 2 and aldehydes or ketones, are converted into the corresponding benzynes upon exposure to either N-bromosuccinimide or lead(IV) acetate; intramolecular trapping by the hydroxyl group then leads to the dihydrobenzofurans 4, 7, 8 and 9 in 38 75% isolated 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