A Comparison of Phosphonium and Phosphonate Carbanion Reagents inReactions with 1,3-Diphenyl-2-(hydroxyimino)-1,3-propanedione

Abstract

1,3-Diphenyl-2-(hydroxyimino)-1,3-propanedione 1 reacted with phosphonium ylides 2a,b to give mainly the substituted 1-hydroxy-2,3-dihydropyrroles 6a,b along with the novel ylides 10a,b whereas the phosphono substituted-N-heterocycles 11a,b and 14a,b were obtained from the reaction of 1 with a-phosphoryl carbanion counterparts 3a,b. Reaction of 1 with cyanomethylene(triphenyl)phosphorane 2c afforded the Wittig product 17 and the oxazole derivative 18 while the phosphono 2,2-disubstituted dihydrooxazole 20 and the diolefin 19 were produced in the reaction with the phosphonate ylide 3c. Application of the unsaturated carbanions 2d and 3d on 1 yielded the pyrrole 23 and the phosphono substituted 2H-1,4-oxazine 25, respectively.The Wittig reaction of compounds other than aldehydes and ketones, 1-3 for example anhydrides, imides and amides as well as a-imino carbonyl compounds, has been extensively studied and in many cases provides a useful method for the preparation of heterocyclic molecules. In contrast, the analogous Wittig-Horner (Horner-Wadswarth-Emmons, HWE) reaction has received a little attention 1c,4 although the reaction of some o-quinonimines with saturated phosphoryl carbanions giving unexpected products has been studied by Boulos and coworkers. 4As part of our continuing study on the application of Wittig synthons on a-imino carbonyl compounds (oximes 5 and hydrazones 6 ) for the synthesis of N-heterocycles, we report in this paper a comparative study on the behavior of 1,3-diphenyl-2-(hydroxyimino)-1,3-propanedione 1 toward alkylidenephosphoranes 2, relative to their phosphonate counterparts 3 (Figure 1). The investigation was undertaken in the hope of formation of N-heterocycles and the relevant phosphonate derivatives.The required oxime 1 was prepared according to the literature. 7 Treatment 8 of 1 with ethoxycarbonylmethylene(triphenyl)phosphorane 2a (2 molar amounts) in boiling chloroform gave diethyl 5-benzoyl-4-phenyl-1-hydroxy-2,3-dihydropyrrole-2,3-dicarboxylate 6a as the major product (48%) along with the novel ylide 10a in 18% yield. Scheme 1 Figure 1Downloaded by: University of Arizona Library. Copyrighted material.

Antimicrobial activity of novel fused nitrogen, sulfur and phosphorus containing-heterocycles and relevant phosphonates with difurylpyridazine species

“…The characteristic signals at 1.24 (dt) and 4.17 (dq) ppm were deshielding of the methylene-protons was, however, attributed to the attached hetero-ring. These signals were attested in 13 The formation of 4 is assumed to proceed through structures 6 and 7 to the intermediates of the reaction between nitriles and phosphorus carbanions. [23][24][25][26][27] Subsequent reaction of the phosphonate esters and loss of ethyl alcohol gave rise to the formation of 2-oxo-thiazaphosphinine 4a and 4b (Scheme 2).…”

“…Thiazaphosphinines 4a, 4b ( 18% yield) and thiaphospholes 5a, 5b ( 36% yield) were isolated (Scheme 1). The structures 4 and 5 were assigned on the basis of 1 H, 13 C, 31 P NMR, IR and MS spectroscopy 20,21 as well as elemental analyses. The IR spectra of 4a and 4b showed the characteristic bands at 1720, 1260 cm -1 due to C(O), ester and P=O groups and the disappearance of the bands at 3160, 2230, 1190 cm -1 due to NH, CN and C=S groups of compound 1.…”

“…The different chemical shifts of the NH 2 protons are the spectroscopic evidence for the presence of intramolecular hydrogen bond between one of the hydrogens of NH 2 -protons and oxygen atom of the P=O bonding in the phosphonate group. In their 13 C NMR, the quaternary -C-3 displayed at 121.6 ppm (d, 1 J P-C = 136 Hz), while C-8 appeared at 85.63 (d, 4 J P-C = 6.6 Hz) and C-9 at 144.7 (d, 3 J P-C = 9.6 Hz). Note 1 with the phosphonate carbanion 3c (Scheme 5) vary markedly from the reaction of the oxygen analogue 2 with the same reagent 3c where oxazaphosphinine 14 and the phosphonate 15 were obtained (Scheme 6).…”

“…The 1 H NMR spectrum of 17 shows a doublet at 5.16 ppm (J = 18.2 Hz), which as previously discussed 42 indicates that the oxygen (= O) on P-2 and the proton on C-3 are cis, and that trans 17.5 ppm, which is within the range expected for the assigned structure. 29 The distinguishing features of 13 A mechanism for the formation of the heterophosphole 5 can be rationalised as occurring through the condensation of 1 with 3a, 3b to elaborate the intermediate 9 accompanied with an elimination of an HCN molecule. [30][31][32] Further intramolecular cyclisation of 9 afforded the phosphole 5 via the loss of ethanol molecule (Scheme 4).…”

“…A continuous trend is observed toward the chemistry of phosphorus containing heterocycles, 1,2 largely, because these compounds, especially those that contained more nitrogen and/or sulfur tend to have higher pharmacological and pesticidal activity. [3][4][5][6] In connection to our previous work [7][8][9][10][11][12][13][14][15][16] on the application of a number of phosphorane and phosphonate carbanions to a variety of nitrogen functions, we studied the antibiotic potency of some fused-and spironitrogen-containing heterophospholes that were isolated from the reactions of Wittig-Horner reagents with , -unsaturated nitriles, 17 and diazo-substrates. 18 These results encouraged us to attempt further preparation of a novel series of fused nitrogen-and sulfur-containing heterophosphorus esters and their relevant phosphonates.…”