1-Aminobenzotriazole functionalisation using directed metallation: new routes to chromanes and chromenes using intramolecular benzyne trapping by alcohols
A new strategy for the synthesis of chromans and chromenes
作者:David W. Knight、Paul B. Little
DOI:10.1016/s0040-4039(98)00937-x
日期:1998.7
Sonogashira coupling of 7-iodobenzotriazole derivative 9 with propargylic alcohols followed by alkyne reduction leads to alkanols 11 or alkanols 12 which cyclize upon benzyne generation to give the iodo-chromanes 14 and iodo-chromenes 16. (C) 1998 Elsevier Science Ltd. All rights reserved.
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
1-Aminobenzotriazole functionalisation using directed metallation: new routes to chromanes and chromenes using intramolecular benzyne trapping by alcohols
作者:David W. Knight、Paul B. Little
DOI:10.1039/b001834l
日期:——
Metallation of 1-(tert-butoxycarbonylamino)benzotriazole 8 leads to the dianionic species 9 which undergoes smooth reactions with a range of electrophiles, under appropriate conditions. The derived iodide 30 undergoes efficient Sonogashira coupling with a range of alk-1-yn-3-ols to provide the expected arylalkynes 33, total or partial reduction of which leads to the arylpropanols 34 and the (Z)-allylic alcohols 40 respectively. N-Deprotection and exposure to N-iodosuccinimide then led to smooth benzyne generation and intramolecular trapping by the hydroxy functions with iodine incorporation to give the iodochromanes 35 and iodochromenes 41 respectively, in respectable overall yields.