A catalyst-free synthesis of α-aminophosphonates in glycerol

Sequential KOtBu/FeCl3-catalyzed reductive phosphonylation of tertiary amides for the synthesis of α-amino phosphonates and phosphines

A simple, mild and efficient sequential KO^tBu/FeCl₃-catalyzed reductive phosphonylation of tertiary amides is herein described. This process first involved the KO^tBu-catalyzed selective semi-reduction of tertiary amides to hemiaminal intermediates by TMDS (1,1,3,3-tetramethyldisiloxane) and then the FeCl₃-catalyzed nucleophilic addition of the hemiaminal intermediates to phosphonates, which allowed the straightforward synthesis of α-amino phosphonates in moderate to good yields. This method applied well to amides and lactams that bear no strong acidic α-hydrogens, and various functional groups, including methoxy, methylthio, cyano, halogen, and heterocycles, could be tolerated.

Synthesis of α-Aminophosphonates and Related Derivatives; the Last Decade of the Kabachnik-Fields Reaction

The Kabachnik-Fields reaction, comprising the condensation of an amine, oxo compound and a P-reagent (generally a >P(O)H species or trialkyl phosphite), still attracts interest due to the challenging synthetic procedures and the potential biological activity of the resulting α-aminophosphonic derivatives. Following the success of the first part (Molecules 2012, 17, 12821), here we summarize the synthetic developments in this field accumulated in the last decade. The procedures compiled include catalytic accomplishments as well as catalyst-free and/or solvent-free "greener" protocols. The products embrace α-aminophosphonates, α-aminophosphinates, and α-aminophosphine oxides along with different bis derivatives from the double phospha-Mannich approach. The newer developments of the aza-Pudovik reactions are also included.

The synthesis of HMF-based α-amino phosphonatesviaone-pot Kabachnik–Fields reaction

The first use of biomass-derived HMF in the one-pot Kabachnik–Fields reaction is reported here. A wide range of furan-based α-amino phosphonates were prepared in moderate to excellent yields under mild, effective and environmentally-benign conditions: iodine as a non-metal catalyst, biobased 2-MeTHF as the solvent and room or moderate temperature. The hydroxymethyl group of HMF persists in the Kabachnik–Fields products, widening the scope of further modification and derivatization compared to those arising from furfural. Issues involving the diastereoselectivity and double Kabachnik–Fields condensation were also faced.

A mild and efficient one-pot protocol for the synthesis of α-amino phosphonates directly from 5-HMF was described.

Sustainable synthesis of 3-substituted phthalides via a catalytic one-pot cascade strategy from 2-formylbenzoic acid with β-keto acids in glycerol

Background: Phthalides are privileged constituents of numerous pharmaceuticals, natural products and agrochemicals and exhibit several biological and therapeutic activities. Therefore, the development of new, facile, and sustainable strategies for the construction of these moieties is highly desired.

Results: A broad substrate scope for β-keto acids was found to be strongly compatible with this catalytic process, affording a wide variety of 3-substituted phthalides in good to excellent yields.

Conclusion: A concise and efficient synthesis strategy of 3-substituted phthalides from 2-formylbenzoic acid and β-keto acids via a catalytic one-pot cascade reaction in glycerol has been accomplished.

Highly efficient one-pot four-component Kabachnik–Fields synthesis of novel α-amino phosphonates under solvent-free and catalyst-free conditions

A simple and safe one-pot four component synthesis of Kabachnik–Fields synthesis of novel α-amino phosphonates under solvent-free and catalyst-free conditions is reported.

Expeditious synthesis of (±)-diethyl 2-alkyl- and 2-aryl-(3-oxoisoindolin-1-yl)phosphonates catalysed by OSU-6

An efficient synthesis of (±)-diethyl 2-alkyl- and 2-aryl-(3-oxoisoindolin-1-yl)phosphonates is reported via condensation of 2-carboxybenzaldehyde with an amine and triethyl phosphite using OSU-6 as the catalyst.