Pd-catalysed ortho-alkoxylation of benzamides N-protected with an iminophosphorane functionality

The oxidative coupling of keto-stabilised iminophosphoranes (IPs) Ph 3 P&z.dbd;NC(O)C 6 H x R y with alcohols R′OH affords the alkoxylated species Ph 3 P&z.dbd;NC(O)C 6 H x −1 R y -2-OR′. The process is catalysed by 10% PdCl 2 (NCMe) 2 , uses oxone® as an oxidant and alcohol R′OH as a source...

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Bibliographic Details
Published in:New journal of chemistry 2015-01, Vol.39 (4), p.377-383
Main Authors: Villuendas, Pedro, Serrano, Elena, Urriolabeitia, Esteban P
Format: Article
Language:English
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Summary:The oxidative coupling of keto-stabilised iminophosphoranes (IPs) Ph 3 P&z.dbd;NC(O)C 6 H x R y with alcohols R′OH affords the alkoxylated species Ph 3 P&z.dbd;NC(O)C 6 H x −1 R y -2-OR′. The process is catalysed by 10% PdCl 2 (NCMe) 2 , uses oxone® as an oxidant and alcohol R′OH as a source of OR′ groups and reaction solvent. The reaction takes place at room temperature regioselectively at the ortho -position of the benzamide ring, gives only the mono-alkoxylated derivatives, and shows tolerance to a variety of functional groups and different primary and secondary alcohols. Better yields were obtained when the aryl ring contains electron-releasing substituents (OMe, Me). The iminophosphorane moiety plays a dual role as the protecting/directing group, and can be hydrolysed to give the corresponding free benzamide. The mild Pd-catalysed ortho -alkoxylation of benzamides, protected as keto-stabilised iminophosphoranes, with alcohols, is regioselective and tolerates different substituents and alcohols.
ISSN:1144-0546
1369-9261
DOI:10.1039/c5nj00189g