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: 3098
Function: getPubMedXML
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
Severity: Warning
Message: Attempt to read property "Count" on bool
Filename: helpers/my_audit_helper.php
Line Number: 3100
Backtrace:
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 3100
Function: _error_handler
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
Carboxylic acids, including amino acids (AAs), have been widely used as reagents for decarboxylative couplings. In contrast to previous decarboxylative couplings that release CO as a waste byproduct, herein we report a novel strategy with simultaneous utilization of both the alkyl and carboxyl components from carboxylic acids. Under this unique strategy, carboxylic acids act as bifunctional reagents in the redox-neutral carbocarboxylation of alkenes. Diverse, inexpensive, and readily available α-AAs take part in such difunctionalizations of activated alkenes via visible-light photoredox catalysis, affording a variety of valuable but otherwise difficult to access γ-aminobutyric acid derivatives (GABAs). Additionally, a series of dipeptides and tripeptides also participate in this photocatalytic carbocarboxylation. Although several challenges exist in this system due to the low concentration and quantitative amount of CO, as well as unproductive side reactions such as hydrodecarboxylation of the carboxylic acids and hydroalkylation of the alkenes, excellent regioselectivity and moderate to high chemoselectivity are achieved. This process features low catalyst loading, mild reaction conditions, high step and atom economy, and good functional group tolerance, and it is readily scalable. The resulting products are subject to efficient derivations, and the overall process is amenable to applications in the late-stage modification of complex compounds. Mechanistic studies indicate that a carbanion is generated catalytically and it acts as the key intermediate to react with CO, which is also generated catalytically and thus remains in low concentration. The overall transformation represents an efficient and sustainable system for organic synthesis, pharmaceutics, and biochemistry.
Download full-text PDF |
Source |
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http://dx.doi.org/10.1021/jacs.0c11896 | DOI Listing |
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