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: 1075
Function: getPubMedXML
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 3195
Function: GetPubMedArticleOutput_2016
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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A facile synthetic method for 4-aryl-4,5-dihydropyrrole-3-carboxylates is developed, with a rhodium-catalyzed ring expansion strategy from readily available 2-(azetidin-3-ylidene) acetates and aryl boronic acids. Mechanistic investigations suggest a novel domino "conjugate addition/N-directed α-C(sp)-H activation" process. The asymmetric catalytic synthesis of the 4-aryl-4,5-dihydropyrrole-3-carboxylate is realized by using QuinoxP* (91-97% ee). The synthetic utility of this protocol is demonstrated by the synthesis of 3,4-disubstituted or 2,3,4-trisubstituted pyrrolidines with excellent diastereoselectivities.
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Source |
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http://dx.doi.org/10.1021/acs.orglett.2c00056 | DOI Listing |