- Palladium-catalyzed reactions of hypophosphorous compounds with allenes, dienes, and allylic electrophiles: Methodology for the synthesis of allylic H-phosphinates
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(Chemical Equation Presented) Hypophosphorous compounds (MOP(O)H 2, M = H, R3NH) effectively participate in metal-catalyzed C-P bond-forming reactions with allenes, dienes, and activated allylic electrophiles under mild conditions. The catalytic system Pd2dba 3/xantphos is crucial to avoid or minimize the competitive reductive transfer-hydrogenation pathway available to hypophosphorous acid derivatives. Further investigation into the allylation mechanism provided access to the analogy allylic acetate - allylic phosphinate, which then led to the development of a Pd-catalyzed rearrangement of preformed allylic phosphinates esters and, ultimately, to a catalytic dehydrative allylation of hypophosphorous acid with allylic alcohols. The reactions disclosed herein constitute efficient synthetic approaches, not only to prepare allylic H-phosphinic acids but also their esters via one-pot tandem processes. In addition, the potential of H-phosphinates as useful synthons for the preparation of other organophosphorous compounds is demonstrated.
- Bravo-Altamirano, Karla,Abrunhosa-Thomas, Isabelle,Montchamp, Jean-Luc
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p. 2292 - 2301
(2008/09/19)
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- Palladium-catalyzed dehydrative allylation of hypophosphorous acid with allylic alcohols
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A novel palladium-catalyzed allylation of H3PO2 with allylic alcohols is described. The phosphorus-carbon bond-forming reaction produces allylic-H-phosphinic acids and water, in the absence of additives. Primary H-phosphinic acids are obtained in excellent yields, whereas secondary H-phosphinic acids react sluggishly. A reusable polymer-supported catalyst is also described. The reaction provides an environmentally sound approach to H-phosphinic acids.
- Bravo-Altamirano, Karla,Montchamp, Jean-Luc
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p. 4169 - 4171
(2007/10/03)
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