Severity: Warning
Message: file_get_contents(https://...@gmail.com&api_key=61f08fa0b96a73de8c900d749fcb997acc09): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
Filename: helpers/my_audit_helper.php
Line Number: 143
Backtrace:
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 143
Function: file_get_contents
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 209
Function: simplexml_load_file_from_url
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 994
Function: getPubMedXML
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 3134
Function: GetPubMedArticleOutput_2016
File: /var/www/html/application/controllers/Detail.php
Line: 574
Function: pubMedSearch_Global
File: /var/www/html/application/controllers/Detail.php
Line: 488
Function: pubMedGetRelatedKeyword
File: /var/www/html/index.php
Line: 316
Function: require_once
Herein, we report a mild, efficient, and rapid approach for the preparation of CF-phenanthridones through a cross-conjugated vinylogous [4 + 2] benzannulation of easily accessible 4-methyl-3-trifluoroacetylquinolones and nitro-olefins. The present transformation is superior to previous approaches for obtaining CF-phenanthridones, in that it proceeds exclusively with the assistance of a simple base, eliminating the need for transition metal catalysts or oxidants. The strong electron-withdrawing nature of the CF-group present in the quinolone moiety promotes the formation of a reactive cross-conjugated vinylogous enolate.
Download full-text PDF |
Source |
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http://dx.doi.org/10.1039/d4ob01480d | DOI Listing |
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