A new and efficient strategy for the preparation of 1,5,2-diazaphosphorines from primary β-enaminophosphonates

Palacios, Francisco; Retana, Ana M. Ochoa de; Oyarzábal, Julen

doi:10.1016/s0040-4020(99)00068-x

Cited by 23 publications

(3 citation statements)

References 38 publications

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“…The obtained α-propargyl phosphonates 5a – j were mostly present in the ( Z )-enamine form based on the coupling constants 3 J CP of ca. 18 Hz, although some ( E )-isomer was also present. For both terminal alkynes 5a – g and internal alkynes 5i – j the E / Z ratio is around 1/9 while for the internal alkyne 5h the ratio is 1/4.…”

Section: Resultsmentioning

confidence: 98%

Preparation of Tetrasubstituted 3-Phosphonopyrroles through Hydroamination: Scope and Limitations

2014

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Phosphonylated pyrroles were obtained by a ZnCl2-catalyzed 5-exo-dig hydroamination of propargylic enamines. These starting compounds were obtained in two steps from commercially available β-ketophosphonates. The method tolerates a wide variety of substituents at the 1,2- and 5-position of the pyrrole, while further derivatization allows for the introduction of substituents at the 4-position via lithiation or halogenation.

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Section: Resultsmentioning

confidence: 98%

Preparation of Tetrasubstituted 3-Phosphonopyrroles through Hydroamination: Scope and Limitations

2014

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“…Hydroamination of r-Fluoroallenylphosphonate. The hydroamination of R-fluoroallenylphosphonate 8 can serve as a conduit to the preparation of fluoroanalogues of enamines 43 and β-enaminophosphonate, a key component in the synthesis of pyrimidone ring systems. 44 Prior to this work, β-fluoroenaminephosphonates were unknown.…”

Section: Resultsmentioning

confidence: 99%

The First α-Fluoroallenylphosphonate, the Synthesis of Conjugated Fluoroenynes, and the Stereoselective Synthesis of Vinylfluorophosphonates Using a New Multifunctional Fluorine-Containing Building Block

Zapata

Hammond

1999

J. Org. Chem.

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Limitations on current methodologies for the introduction of CF(2) and CFH in complex alpha-fluorophosphonates led to the synthesis of a fluorine-containing building block TIPS-C&tbd1;CCFXP(O)(OEt)(2), where X = H or F. This multifunctional fluorine synthon reacts with carbonyl compounds under WHE conditions to give high yields of fluorinated conjugated enynes and enediyne. When X = F, trapping of the desilylated anion with an electrophile after TIPS removal provided exclusive access to gamma-substituted derivatives of alpha-fluorophosphonates. When X = H, TBAF deprotection of the silyl group yields H(2)C=C=CFP(O)(OEt)(2) through an allenyl-propargyl resonance stabilized anion. The allene moiety has been used as template in the stereoselective synthesis of alpha-fluoro-beta, gamma-diiodopropenyl phosphonate, via electrophilic iodination, and alpha-fluoro-gamma-amino-alpha,beta-unsaturated phosphonates, including unsaturated phosphononucleosides, by nucleophilic displacement of an allylic iodide. Hydroamination of H(2)C=C=CFP(O)(OEt)(2) using secondary amines produced (Z)-alpha-fluoroenaminophosphonates, whereas Diels-Alder cycloaddition with cyclopentadiene provides the corresponding exocyclic vinylfluorophosphonate.

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“…Moreover, enamines have attracted a great deal of attention in recent years because of their range of applications, , and especially metaloenamines, carbanions derived from enamines or enolizable imines, are useful substrates for the regio- and stereoselective carbon−carbon bond formation reaction with electrophilic reagents. , However, primary enamines, despite their potential interest as synthons in organic synthesis for the preparation of acyclic and cyclic derivatives, have been less studied, given that they are unstable unless conjugated with an electron-withdrawing group on the β-carbon atom . In connection with our interest in the preparation of three-, five-, and six-membered phosphorus-substituted nitrogen heterocycles, we described the synthesis of stable primary enamines derived from phosphonates and carboxylates as well as their synthetic use for the preparation of functionalized acyclic compounds, aminophosphonate derivatives, and phosphorus-containing heterocycles . In this context, we reported the first synthesis of fluorinated primary enamine phosphonates by reaction of alkylphosphonates I with fluoroalkyl nitriles II (see Scheme ) and the synthetic application of these intermediates as starting material for the preparation of acyclic fluoroalkyl nitrogenated derivatives .…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Fluoroalkylated β-Aminophosphonates and Pyridines from Primary β-Enaminophosphonates

et al. 2008

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A simple and efficient stereoselective synthesis of fluorine containing beta-aminophosphonates by reduction of beta-enaminophosphonates is described. Reduction with sodium cyanborohydride in the presence of zinc chloride and the catalytic hydrogenation of beta-enaminophosphonates gives beta-aminophosphonates. beta-Enaminophosphonates are also used as intermediates for the regioselective synthesis of fluoroalkyl-substituted pyridines.

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A new and efficient strategy for the preparation of 1,5,2-diazaphosphorines from primary β-enaminophosphonates

Cited by 23 publications

References 38 publications

Preparation of Tetrasubstituted 3-Phosphonopyrroles through Hydroamination: Scope and Limitations

Preparation of Tetrasubstituted 3-Phosphonopyrroles through Hydroamination: Scope and Limitations

The First α-Fluoroallenylphosphonate, the Synthesis of Conjugated Fluoroenynes, and the Stereoselective Synthesis of Vinylfluorophosphonates Using a New Multifunctional Fluorine-Containing Building Block

Synthesis of Fluoroalkylated β-Aminophosphonates and Pyridines from Primary β-Enaminophosphonates

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