Highly Enantioselective Hydrogenation of Enol Ester Phosphonates: A Versatile Procedure for the Preparation of Chiral β‐Hydroxyphosphonates

Abstract

In their Communication, the authors have found errors in Tables 1 and 2. The enantioselectivity of product 2 a (Table 1, entry 4) was 99 % ee and not 59 % ee.

Features and Application in Asymmetric Catalysis of Chiral Phosphine–Phosphite Ligands

“…In this context, a particularly interesting case is constituted by the hydrogenation of the β‐MeO enamides, related to the synthesis of the antiepileptic drug Lacosamide (Scheme ). In this hydrogenation, a byproduct resulting from the elimination of MeOH was observed 58. This secondary process was affected by the nature of the solvent and could be minimized in DCM.…”

“…This research group has also investigated the hydrogenation of β‐acyloxyvinyl phosphonates. Notably, this reaction produces an undesired elimination byproduct (Scheme ) 58,64. By tuning the structure of the P‐OP ligand, the amount of elimination product could be minimized and the catalyst with ligand L7b provided high chemo‐ and enantioselectivities in the reduction of diverse substrates.…”

Stereoselective synthesis of GABOB, carnitine and statine phosphonates analogues

“…[69][70][71][72] Recently, Pizzano et al 73 reported the synthesis of enantiomerically pure (R)-GABOB P 7 via the highly enantioselective hydrogenation of enol ester phosphonate 84. Thus, the reaction of b-ketopropylphosphonate 83 with NaH followed by the addition of benzoyl chloride (BzCl) afforded the corresponding enol Z-84 as the only isomer isolable, which by catalytic hydrogenation in the presence of complex [Rh(cod) (85)]BF 4 , (cod = cycloocta-1,5-diene) gave the b-benzyloxyphosphonate (R)-86 in 87% yield and 99% ee.…”

Highly Enantioselective Hydrogenation of β‐Acyloxy and β‐Acylamino α,β‐Unsaturated Phosphonates Catalyzed by Rhodium Phosphane‐Phosphite Complexes

“…They resemble carboxylic esters, while they directly bind a sterically encumbered group to the olefinic fragment which hinders olefin coordination and presumably disfavours catalyst activity 11. Moreover, β‐(acyloxy)‐12 and β‐(acylamino)vinylphosphonates13 introduce an additional challenging feature, as the Z isomers are more stable, while for the corresponding α,β‐unsaturated esters, reduction of the Z olefins is more difficult than that of the E isomers 14. In addition, the hydrogenation of these β‐functionalized phosphonates generates appropriate precursors for the preparation of β‐amino‐ and β‐hydroxyphosphonates, which possess a great range of biologically relevant properties 15.…”

“…In particular, cationic rhodium catalyst precursors [Rh(COD)(P‐OP)]BF 4 [P‐OP= 1 ( 3 ), 2 ( 4 )] have shown excellent levels of enantioselectivity in the hydrogenation of several types of olefins 11,17. In a preliminary communication we described the application of these catalysts in the hydrogenation of several β‐(benzoyloxy)vinylphosphonates 12. Remarkably, these substrates were reduced with high enantioselectivities, but the reactions also produced an unexpected achiral phosphonate resulting from the elimination of the benzoate group.…”