Severity: Warning
Message: file_get_contents(https://...@gmail.com&api_key=61f08fa0b96a73de8c900d749fcb997acc09&a=1): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
Filename: helpers/my_audit_helper.php
Line Number: 197
Backtrace:
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 197
Function: file_get_contents
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 271
Function: simplexml_load_file_from_url
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 3165
Function: getPubMedXML
File: /var/www/html/application/controllers/Detail.php
Line: 597
Function: pubMedSearch_Global
File: /var/www/html/application/controllers/Detail.php
Line: 511
Function: pubMedGetRelatedKeyword
File: /var/www/html/index.php
Line: 317
Function: require_once
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The conjugate additions of nucleophiles to conjugate acceptors are among the most powerful hetero-carbon bond formation reactions. The conjugate addition normally occurs via a β-nucleophilic addition, resulting in the formation of a stabilized α-carbanion intermediate that can be subsequently quenched by electrophiles or protons. Nevertheless, the inverse conjugate addition involving an α-specific nucleophilic addition remains less explored because of the electronic mismatch. In this research, we disclosed an α-specific nucleophilic addition of the nucleophiles including Py·HF, TBACl, HOR, HO, HO, RCOH, and pyrazole to conjugate acceptors concurrent with a trifluoromethylation. This umpolung and inversely regioselective conjugate addition, enabled by a visible light-induced redox photocatalysis, occurred via an unusual α-nucleophilic addition other than the normal β-nucleophilic addition to efficiently generate diverse α-functionalized CF-containing amides/esters. The broad substrate scope, excellent functional-group tolerance, and versatile late-stage derivatizations as well as the biologically and functionally important CF-containing products demonstrated the potential applications of this protocol in materials, agrochemicals, and pharmaceutical chemistry.
Download full-text PDF |
Source |
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC11817926 | PMC |
http://dx.doi.org/10.1126/sciadv.adt2715 | DOI Listing |