Synthesis 2022; 54(01): 171-183
DOI: 10.1055/a-1578-2848
paper

Multigram Synthesis of Difluoromethylene Phosphonic and Phosphinic Amides and Phosphine Oxides via Formal [2,3]-Sigmatropic Allyl Phosphite–Allylphosphonate Rearrangement

,
Gerd-Volker Röschenthaler
This work has been funded by the Bundesministerium für Wirtschaft und Energie (German Federal Ministry of Economic Affairs and Energy) through the ‘GO3’ project (No. 03ETE002C).


Abstract

We describe a method for the preparation of CF2-P(V) building blocks and monomers for biological and materials chemistry applications in multigram quantities based on a formal [2,3]-sigmatropic phospha-Wittig rearrangement of readily available fluoroallyl bis(amido)phosphites, amido(aryl)phosphonites, and diarylphosphinites. The proposed intramolecular phosphorylation approach complements the currently prevailing phosphoryldifluoromethylation methods by providing a straightforward access to difluoromethylene phosphonate analogues bearing dialkylamino and/or aryl substituents at the phosphoryl group. An important advantage of the developed method is that it does not rely on ozone-depleting HCF2Cl and CF2Br2 necessary for the preparation of phosphoryldifluoromethylating reagents. 2,3,3-Trifluoroallyloxy P(III) derivatives substituted with two dialkylamino and/or aryl groups underwent a facile [2,3]-rearrangement to give difluoromethylene phosphonic and phosphinic amides and phosphine oxides on up to a 0.15 mol (30 g) scale. The reaction was extended to P(III) derivatives of 1-substituted 2,3,3-trifluoro- and 3,3-difluoroallylic alcohols readily available from carbonyl compounds and, respectively, 1,1,1,2-tetrafluoroethane and O-protected 2,2,2-trifluoroethanols. Products derived from O-(tetrahydropyran-2-yl)-2,2,2-trifluoroethanol were synthesized and deprotected in a one-pot multistep protocol to give phosphonic and phosphinic amide and phosphine oxide analogues of α,α-difluoro-β-ketophosphonates on a multigram scale.

Supporting Information



Publication History

Received: 26 June 2021

Accepted after revision: 04 August 2021

Accepted Manuscript online:
04 August 2021

Article published online:
02 September 2021

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