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New Developments on the Hirao Reactions, Especially from 'Green' Point of View
- Source :
- Current Organic Synthesis
- Publication Year :
- 2019
-
Abstract
- Background: The Hirao reaction discovered ca. 35 years ago is an important P–C coupling protocol between dialkyl phosphites and aryl halides in the presence of Pd(PPh3)4 as the catalyst and a base to provide aryl phosphonates. Then, the reaction was extended to other Preagents, such as secondary phosphine oxides and H-phosphinates and to other aryl and hetaryl derivatives to afford also phosphinic esters and tertiary phosphine oxides. Instead of the Pd(PPh3)4 catalyst, Pd(OAc)2 and Ni-salts were also applied as catalyst precursors together with a number of mono- and bidentate P-ligands. Objective: In our review, we undertook to summarize the target reaction with a special stress on the developments attained in the last 6 years, hence this paper is an update of our earlier reviews in a similar topic. Conclusion: “Greener” syntheses aimed at utilizing phase transfer catalytic and microwave-assisted approaches, even under “P-ligand-free. or even solvent-free conditions are the up-to date versions of the classical Hirao reaction. The mechanism of the reaction is also in the focus these days.
Details
- ISSN :
- 15701794
- Volume :
- 16
- Issue :
- 4
- Database :
- OpenAIRE
- Journal :
- Current organic synthesis
- Accession number :
- edsair.doi.dedup.....b251fdd19d8acfa68ead164715999d4e