Chemoselective entry to 5-mercaptotriazoles by condensation of acetylenic esters with triphenylphosphine

Davood Aghaei Afshar

doi:10.1016/j.arabjc.2010.10.015

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Original article

6 (

); 389-392

doi:

10.1016/j.arabjc.2010.10.015

Chemoselective entry to 5-mercaptotriazoles by condensation of acetylenic esters with triphenylphosphine

Davood Aghaei Afshar^*

Department of Chemistry, Shahid Dadbin Institute of Kerman, Kerman 76171 Iran

*Tel.: +98 341 212 3560 da_ag_af@yahoo.co.in (Davood Aghaei Afshar)

Received: 2010-9-23, Accepted: 2010-10-14, Published: 2010-10-01

Disclaimer:
This article was originally published by Elsevier and was migrated to Scientific Scholar after the change of Publisher.

1 For two rotamers.

Abstract

A new kind of 1,2,4-triazol derivatives containing ylide moiety were designed and synthesized. The reaction is performed by condensation of dialkyl acetylenedicarboxylate with 5-aryl-2H-1,2,4-triazol-3-thiol in the presence of Ph₃P. In these cases, the reactions take place on the sulfur atom in good to excellent yields via a chemoselective manner.

Keywords

Acetylenic esters

Phosphorus ylides

Triazole

Dialkyl acetylenedicarboxylate

Triphenylphosphine

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1 Introduction

The development of simple synthetic routes for widely used organic compounds from readily available reagents is one of the goals in organic chemistry (Laszlo, 1995). Organophosphorus compounds are synthetic targets of interest, because of their applications in variety of industrial, biological, pharmacological activities and also in chemical synthetic uses (Corbridge, 1995). Among the phosphorus compounds, phosphorus ylides play an important role in the synthesis of organic molecules (Ramazani et al., 2008; Yavari and Islami, 1998), because these compounds give an elegant access to other functional groups and a number of these compounds were employed in the preparation of natural products such as β-carotene (Yuan et al., 2008). They can be prepared by the reaction of a phosphonium salt (Maeycker, 1965) with a base and synthesis of phosphonium salt often requires forcing conditions. Frequently, the phosphine and organic halide must be heated to reflux for several hours, and in some cases several days, to obtain the desired phosphonium salt (Cadogan, 1979). In recent years methods for the preparation of this class compounds has been developed by using a novel approach employing vinyl phosphonium salts (Yavari et al., 2003; Hassani et al., 2009). In addition, triazole compounds have been introduced as an important class of plant growth regulators (Davis, 1991; Kanno, 1987) along with fungicidal and herbicidal properties (El-Zemity et al., 2006). Triazoles containing fluorine atoms in the aryl ring have also shown some insecticidal activity against house mosquito larva (Liu et al., 2000). Our literature survey reveals that most of 5-aryl-2H-1,2,4-triazol-3-thiol derivatives in which the sulfur atom having a chain have exhibited antimicrobial, antifungal and anti-inflammatory activities (Seyhan et al., 1999; Ulusoy et al., 2001).

Due to the usefulness of these compounds and their important applications in pharmaceutical industry now we wish to design molecules containing these functional groups. Herein, we present our investigation towards this goal.

2 Materials and methods

All common reagents and solvents were used as obtained from commercial suppliers without further purification. The ¹H and ¹³C NMR spectra were recorded on a Bruker DRX-500 AVANCE (¹H NMR at 500 MHz, and ¹³C at 125 MHz). Melting points were obtained on a Gallenkamp melting point apparatus and are uncorrected. Elemental CHN analyses were performed by University of Tarbiat Moalem using a Heracus CHN-O Rapid analyzer. IR spectra were measured on a Mattson 1000 FT-IR spectrometer.

2.1

2.1 General procedure

At ambient temperature dimethyl acetylenedicarboxylate (0.24 mL, 2 mmol) was added dropwise to a stirred solution of triphenylphosphine (0.53 g, 2 mmol) and 3-fluoroaryl-5-mercapto-1,2,4-triazol (2 mmol) in 20 mL of a mixture of hexane–ethyl acetate (1:2). After the addition was complete (approximately 30 min) the mixture was stirred for an additional 1 h and was subsequently filtered. The solid collected in the filter was washed thoroughly with ethyl acetate to give a white powder.

2.1.1

2.1.1 Dimethyl-2-{[3-(3-fluorophenyl)-1H-1,2,4-triazol-5-yl]sulfanyl}-3-(1,1,1-triphenyl-λ⁵-phosphanylidene) succinate 3a

(1.1 g, m.p. 156–158 °C, yield 91%); IR (KBr) (ν_max, cm⁻¹): 1760, 1716 and 1636 (C⚌O). Anal. Calcd. for C₃₂H₂₇FN₃O₄PS (599.5): C, 64.11; H, 4.51; N, 7.01%. Found: C, 63.83; H, 4.43; N, 6.93%.

Isomer (Z) (68%) ¹H NMR (500 MHz, Me₂SO): δ 3.0 and 3.7 (s, 2OCH₃), 5.7 (d, ³J_PH = 22.4 Hz, P⚌C–¹³CH), 7.4–7.8 (38H, m, arom),¹ 13.9 (1H, brs, NH). ¹³C NMR (125.77 MHz, Me₂SO): δ 50.3 (d, ¹J_PC = 141.4 Hz, C⚌P),¹ 51.9 and 52.2 (2OCH₃), 61.3 (d, ²J_PC = 14.1 Hz, P⚌C–CH), 112.0 (d, ²J_FC = 20.9 Hz, C^ortho), 117.3 (d, ²J_Fc = 21 Hz, C⚌C–F),¹ 121.4 (s, C^para), 125.4 (d, ¹J_PC = 92 Hz, C^ipso), 128.8 (d, ³J_PC = 12.2 Hz, C^meta), 131.3 (s, C^meta), 132.2 (d, ⁴J_PC = 2.5 Hz, C^para), 132.9 (s, C^meta), 133.2 (d, ²J_PC = 10.9 Hz, C^ortho), 162.2 (d, ¹J_FC = 244 Hz, C^ipso), 164.7 (s, C⚌N),¹ 166.1 (s, C⚌N),¹ 168.2 (d, ²J_PC = 13.4 Hz, C⚌O), 169.11 (d, ³J_PC = 11.3 Hz, C⚌O). Isomer (E) (32%) ¹H NMR (500 MHz, Me₂SO): δ 3.4 and 3.69 (s, 2OCH₃), 5.7 (d, ³J_PH = 17.8 Hz, P⚌C–¹³CH, 13.8 (1H, brs, NH). ¹³C NMR (125.77 MHz, Me₂SO): δ 51.7 and 52.0 (2OCH₃), 60.3 (d, ²J_PC = 14.3 Hz, P⚌C–CH), 112.4 (d, ²J_FC = 24.3 Hz, C^ortho), 121.7 (s, C^para), 126.1 (d, ¹J_PC = 91.6 Hz, C^ipso), 128.6 (d, ³J_PC = 12.1 Hz, C^meta), 131.4 (s, C^meta), 131.9 (d, ⁴J_PC = 2.5 Hz, C^para), 133.1 (s, C^meta), 133.3 (d, ²J_PC = 11.3 Hz, C^ortho), 169.2 (d, ³J_PC = 12.2 Hz, C⚌O), 169.8 (d, ²J_PC = 17.4 Hz, C⚌O).

2.1.2

2.1.2 Diethyl-2-{[3-(2-fluorophenyl)-1H-1,2,4-triazol-5-yl]sulfanyl}-3-(1,1,1-triphenyl-λ⁵-phosphanylidene) succinate 3b

(1.0 g, m.p. 134–136 °C, yield 81%); IR (KBr) (ν_max, cm⁻¹): 1741, 1716 and 1617 (C⚌O). Anal. Calcd. for C₃₄H₃₁FN₃O₄PS (627): C, 65.07; H, 4.94; N, 6.69%. Found: C, 64.70; H, 4.84; N, 6.62%.

Isomer (Z) (58%) ¹H NMR (500 MHz, Me₂SO): δ 0.35 and 1.20 (T, 6H, ³J_HH = 7.0 and 7.1 Hz, 2CH₃), 3.5–3.9 (8H, m, OCH₂),¹ 5.4 (d, ³J_PH = 20.5 Hz, P⚌C–¹³CH), 7.4–7.8 (38H, m, arom),¹ 13.6 (1H, brs, NH).¹ ¹³C NMR (125.77 MHz, Me₂SO): δ 14.2 and 14.5 (2CH₃), 57.7 (d, ¹J_PC = 84.8 Hz, C⚌P),¹ 60.8 (d, ²J_PC = 15.9 Hz, P⚌C–CH), 61.0 and 61.1 (2OCH₂), 114.6 (d, ²J_FC = 11.3 Hz, C⚌C–F),¹ 117.2 (d, ²J_Fc = 21 Hz, C⚌C–F), 125.5 (s, C^para),¹ 127.0 (d, ¹J_PC = 91.7 Hz, C^ipso), 129.3 (d, ³J_PC = 11.9 Hz, C^meta), 129.6 (s, C^meta), 132.7 (s, C^para),¹ 133.2 (d, ³J_FC = 11.4 Hz, C^meta), 133.8 (d, ²J_PC = 9.7 Hz, C^ortho),¹ 159.6 (d, ¹J_FC = 253 Hz, C^ipso),¹ 166.4 (C⚌N),¹ 168.3 (d, ²J_PC = 13.2 Hz, C⚌O), 169.2 (d, ³J_PC = 10.9 Hz, C⚌O). Isomer (E) (42%) ¹H NMR (500 MHz, Me₂SO): δ 1.0 and 1.22 (T, 6H, ³J_HH = 7.0 and 7.1 Hz, 2CH₃), 5.6 (d, ³J_PH = 18.9 Hz, P⚌C–¹³CH). ¹³C NMR: δ 14.5 and 15.1 (2CH₃), 61.0 (d, ²J_PC = 14.1 Hz, P⚌C–CH), 61.8 and 61.9 (2OCH₂), 117.3 (d, ²J_Fc = 20.8 Hz, C⚌C–F), 128.3 (d, ¹J_PC = 92 Hz, C^ipso), 129.3 (d, ³J_PC = 12.0 Hz, C^meta), 131.9 (d, ³J_FC = 9.8 Hz, C^meta), 169.3 (d, ²J_PC = 12.3 Hz, C⚌O), 170.2 (d, ³J_PC = 18.4 Hz, C⚌O).

2.1.3

2.1.3 Dimethyl-2-{[3-(2-fluorophenyl)-1H-1,2,4-triazol-5-yl]sulfanyl}-3-(1,1,1-triphenyl-λ⁵-phosphanylidene) succinate 3c

(1.12 g, m.p. 157–158 °C, yield 93%); IR (KBr) (ν_max, cm⁻¹): 1760, 1716 and 1640 (C⚌O). Anal. Calcd. for C₃₂H₂₇FN₃O₄PS (599.5): C, 64.11; H, 4.51; N, 7.01%. Found: C, 63.63; H, 4.38; N, 6.93%.

Isomer (Z) (52%) ¹H NMR (500 MHz, Me₂SO): δ 3.4 and 3.5 (s, 2OCH₃), 5.5 (d, ³J_PH = 19.5 Hz, P⚌C–¹³CH),¹ 7.4–7.8 (38H, m, arom),¹ 13.6 (1H, brs, NH). ¹³C NMR (125.77 MHz, Me₂SO): δ 49.7 (d, ¹J_PC = 150 Hz, C⚌P),¹ 52.5 and 52.77 (2OCH₃), 62.5 (d, ²J_PC = 14.1 Hz, P⚌C–CH),¹ 117.4 (s, C^ortho, C⚌C–F),¹ 125.5 (s, C^ortho, C⚌C–F),¹ 126.7 (d, ¹J_PC = 82.0 Hz, C^ipso), 129.4 (d, ³J_PC = 12.2 Hz, C^meta), 129.63 (s, C^para), 132 (s, C^meta, C⚌C–C–F), 132.7 (d, ⁴J_PC = 2.6 Hz, C^para), 133.8 (d, ²J_PC = 10.1 Hz, C^ortho), 166.6 (s, C⚌N),¹ 174.6 (d, ²J_PC = 13.5 Hz, C⚌O),¹ 175.2 (d, ³J_PC = 11.9 Hz, C⚌O).¹

Isomer (E) (48%) ¹H NMR (500 MHz, Me₂SO): δ 2.9 and 3.6 (s, 2OCH₃), 13.8 (1H, brs, NH). ¹³C NMR (125.77 MHz, Me₂SO): δ 52.4 and 52.6 (2OCH₃), 126.0 (d, ¹J_PC = 82.7 Hz, C^ipso), 129.2 (d, ³J_PC = 11.8 Hz, C^meta), 130.0 (s, C^para), 131.9 (s, C^meta, C⚌C–C–F), 132.5 (d, ⁴J_PC = 8.8 Hz, C^para), 133.8 (d, ²J_PC = 14.0 Hz, C^ortho).

2.1.4

2.1.4 Dimethyl-2-{[3-phenyl-1H-1,2,4-triazol-5-yl]sulfanyl}-3-(1,1,1-triphenyl-λ⁵-phosphanylidene) succinate 3d

(0.94 g, m.p. 157–159 °C, yield 80%); IR (KBr) (ν_max, cm⁻¹): 1740, 1716 and 1617 (C⚌O). Anal. Calcd. for C₃₂H₂₈N₃O₄PS (581): C, 65.9; H, 4.82; N, 7.23%. Found: C, 65.39; H, 4.73; N, 7.16%. Isomer (Z) (53%) ¹H NMR (500 MHz, Me₂SO): δ 2.99 and 3.5 (s, 2OCH₃), 5.6 (d, ³J_PH = 17 Hz, P⚌C–¹³CH),¹ 7.5–7.9 (40H, m, arom),¹ 13.73 (1H, brs, NH). ¹³C NMR (125.77 MHz, Me₂SO): δ 49.8 (d, ¹J_PC = 143.5 Hz, C⚌P),¹ 52.4 and 52.8 (2OCH₃), 61.7 (d, ²J_PC = 14.5 Hz, P⚌C–CH), 125.8 (s, C^ortho), 126.8 (d, ¹J_PC = 82.7 Hz, C^ipso), 129.4 (d, ³J_PC = 12.1 Hz, C^meta), 129.6 (S, C^para), 131.9 (s, C^meta), 132.7 (d, ⁴J_pc = 2.6 Hz, C^para), 133.5 (s, C^ipso), 133.8 (d, ²J_PC = 10.4 Hz, C^ortho), 147.6 (s, C⚌N), 168.8 (d, ²J_PC = 13 Hz, C⚌O), 169.8 (d, ³J_PC = 15 Hz, C⚌O). Isomer (E) (47%) ¹H NMR (500 MHz, Me₂SO): δ 3.4 and 3.5 (s, 2OCH₃), 13.8 (1H, brs, NH). ¹³C NMR (125.77 MHz, Me₂SO): δ 52.3 and 52.6 (2OCH₃), 60.7 (d, ²J_PC = 14.8 Hz, P⚌C–CH), 125.7 (s, C^ortho), 126.0 (d, ¹J_PC = 82.9 Hz, C^ipso), 129.2 (d, ³J_PC = 11.8 Hz, C^meta), 129.7 (s, C^para), 132.0 (s, C^meta) 132.5 (d, ⁴J_pc = 2.5 Hz, C^para), 133.7 (s, C^ipso), 133.9 (d, ²J_PC = 10.5 Hz, C^ortho), 147.7 (s, C⚌N), 169.9 (d, ²J_PC = 11 Hz, C⚌O), 170.4 (d, ³J_PC = 17.3 Hz, C⚌O).

3 Results and discussion

As a continuous work we examined the reaction of 5-aryl-2H-1,2,4-triazol-3-thiol and dialkyl acetylenedicarboxylate in order to prepare synthetically useful heterocyclic compounds containing phosphorus atom. Combination of equimolar quantities of 1 with dimethyl or diethyl acetylenedicarboxylate and Ph₃P in ambient temperature resulted in 80–93% yield of S-substituted triazoles containing succinic esters chain 3a–d (Scheme 1). In the basis of chemistry of trivalent phosphorus nucleophiles (Becker, 1980; Kolodiazhnyi, 1998), it is reasonable to assume that treatment of triphenylphosphine with acetylenic esters in ethyl acetate as a solvent generated the corresponding zwitter ion in situ which, on further reaction with SH group of triazoles, led to the formation of a salt. Then the positively charged ion is attacked by the conjugated base of SH group to form compounds 3.

It is important to note that in the protonation step the SH group acts as a stronger acid than the NH group. Thus, under the present reaction condition compound 3 is formed as the only product in a chemoselective manner and the compound 4 is not formed (Scheme 1).

Compounds 3a–d were deduced on the basis of their spectroscopic data such as the ¹H NMR, ¹³C NMR, IR and elemental analyses data. These data are consistent with the presence of two rotational isomers (Bestmann et al., 1966; Hooper et al., 1994). The ylide moiety in these compounds is strongly conjugated with adjacent carbonyl group and rotation about the partial double bond in 3-(E) and 3-(Z) geometrical isomers slows at room temperature (Scheme 2).

The ¹H NMR spectrum of 3a showed four sharp lines (δ = 2.99, 3.43, 3.69 and 3.75 ppm) due to methoxy protons along with signals for methine protons at δ = 5.66 and 5.71 ppm, which appear as two doublets (³J_PH = 22.4 Hz) and (³J_PH = 17.8 Hz), respectively, for the major and minor geometrical isomers and two fairly broad signals at δ = 13.80 and 13.78 ppm for protons of NH groups. The fully proton decoupled ¹³C NMR spectrum of 3a displayed 31 distinct resonances in agreement with the mixture of two rotamers. Although the presence of the ³¹P nucleus complicates both the ¹H and ¹³C NMR spectra of 3a, it helps in assignment of signals by long-range spin–spin couplings with ¹H and ¹³C nuclei. Fluorine nucleus coupled with some hydrogen and carbon atoms of the aromatic rings thus, the ¹H and ¹³C spectra of this region were complicated. For example, in the fully proton decoupled ¹³C NMR spectrum of 3a, the signal due to the carbon carrying F atom was appeared as a doublet with a coupling constant equal to 244 Hz. The ¹H and ¹³C NMR spectra of triazoles 3b–d are similar to those of 3a, except for the signals from the ester groups or aromatic rings, which appear as characteristic resonance lines with the corresponding chemical shifts.

Acknowledgement

We thank the Shahid Shahid Dadbin Institute for financial support as a Grant-in Aid for Scientific Research.

References

Becker K., . Tetrahedron. 1980;36:1717.
Bestmann H.J., Joachim G., Lengyel T., Oth J.F., Merenyi R., Weitkamp H., . Tetrahedron Lett. 1966:3355.
Cadogan J.I.G., . Organophosphorus Reagents in Organic Synthesis. New York: Academic; 1979.
Corbridge D.E.C., . Phosphorus: An Outline of the Chemistry Biochemistry and Uses (fifth ed.). Amsterdam: Elsevier; 1995.
Davis T.D., . J. Arborcult.. 1991;17:167.
El-Zemity S.R., El-Shazly A.M., Kadous E.A., . J. Appl. Sci. Res.. 2006;2:1266.
Hassani Z., Islami M.R., Moradi A., Yazdi Rouh-Alamini M., . Phosphorus Sulfur Silicon Relat. Elem.. 2009;184:568.
Hooper D.L., Garagan S., Kayser M.M., . J. Org. Chem.. 1994;59:1126.
Kanno H., . Pure Appl. Chem.. 1987;59:1027.
Kolodiazhnyi O.I., . Tetrahedron Asymmetry. 1998;9:1279.
Laszlo P., . Organic Reactions: Simplicity and Logic. New York: Wiley–VCH; 1995.
Liu S., Qian X., Song G., Chen J., Chen W., . J. Fluorine Chem.. 2000;105:111.
Maeycker A., . Organic Reactions. Vol vol. 14. New York: Wiley; 1965. p. 270
Ramazani A., Kazemizadeh A.R., Ahmadi E., Noshiranzadeh N., Souldozi A., . Curr. Org. Chem.. 2008;12:59.
Seyhan E., Sultan N., Rukiye B., . Il Farmaco. 1999;53:773.
Ulusoy N., Gursoy A., Otuk G., . Il Farmaco. 2001;56:947.
Yavari I., Islami M.R., . J. Chem. Res., Synop. 1998:166.
Yavari I., Alizadeh A., Anary-Abbasinejad M., . Phosphorus Sulfur Silicon Relat. Elem.. 2003;178:269.
Yuan Y., Gao Y., Mao L., Zhao J., . Food Chem.. 2008;107:1300.

Introduction

Materials and methods

General procedure

Results and discussion

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[1] Becker K., . Tetrahedron. 1980;36:1717.

[2] Bestmann H.J., Joachim G., Lengyel T., Oth J.F., Merenyi R., Weitkamp H., . Tetrahedron Lett. 1966:3355.

[3] Cadogan J.I.G., . Organophosphorus Reagents in Organic Synthesis. New York: Academic; 1979.

[4] Corbridge D.E.C., . Phosphorus: An Outline of the Chemistry Biochemistry and Uses (fifth ed.). Amsterdam: Elsevier; 1995.

[5] Davis T.D., . J. Arborcult.. 1991;17:167.

[6] El-Zemity S.R., El-Shazly A.M., Kadous E.A., . J. Appl. Sci. Res.. 2006;2:1266.

[7] Hassani Z., Islami M.R., Moradi A., Yazdi Rouh-Alamini M., . Phosphorus Sulfur Silicon Relat. Elem.. 2009;184:568.

[8] Hooper D.L., Garagan S., Kayser M.M., . J. Org. Chem.. 1994;59:1126.

[9] Kanno H., . Pure Appl. Chem.. 1987;59:1027.

[10] Kolodiazhnyi O.I., . Tetrahedron Asymmetry. 1998;9:1279.

[11] Laszlo P., . Organic Reactions: Simplicity and Logic. New York: Wiley–VCH; 1995.

[12] Liu S., Qian X., Song G., Chen J., Chen W., . J. Fluorine Chem.. 2000;105:111.

[13] Maeycker A., . Organic Reactions. Vol vol. 14. New York: Wiley; 1965. p. 270

[14] Ramazani A., Kazemizadeh A.R., Ahmadi E., Noshiranzadeh N., Souldozi A., . Curr. Org. Chem.. 2008;12:59.

[15] Seyhan E., Sultan N., Rukiye B., . Il Farmaco. 1999;53:773.

[16] Ulusoy N., Gursoy A., Otuk G., . Il Farmaco. 2001;56:947.

[17] Yavari I., Islami M.R., . J. Chem. Res., Synop. 1998:166.

[18] Yavari I., Alizadeh A., Anary-Abbasinejad M., . Phosphorus Sulfur Silicon Relat. Elem.. 2003;178:269.

[19] Yuan Y., Gao Y., Mao L., Zhao J., . Food Chem.. 2008;107:1300.

Chemoselective entry to 5-mercaptotriazoles by condensation of acetylenic esters with triphenylphosphine

Abstract

Keywords

Acetylenic esters

Phosphorus ylides

Triazole

Dialkyl acetylenedicarboxylate

Triphenylphosphine

1 Introduction

2 Materials and methods

2.1 General procedure

2.1.1 Dimethyl-2-{[3-(3-fluorophenyl)-1H-1,2,4-triazol-5-yl]sulfanyl}-3-(1,1,1-triphenyl-λ5-phosphanylidene) succinate 3a

2.1.2 Diethyl-2-{[3-(2-fluorophenyl)-1H-1,2,4-triazol-5-yl]sulfanyl}-3-(1,1,1-triphenyl-λ5-phosphanylidene) succinate 3b

2.1.3 Dimethyl-2-{[3-(2-fluorophenyl)-1H-1,2,4-triazol-5-yl]sulfanyl}-3-(1,1,1-triphenyl-λ5-phosphanylidene) succinate 3c

2.1.4 Dimethyl-2-{[3-phenyl-1H-1,2,4-triazol-5-yl]sulfanyl}-3-(1,1,1-triphenyl-λ5-phosphanylidene) succinate 3d

3 Results and discussion

Acknowledgement

References

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2.1.1 Dimethyl-2-{[3-(3-fluorophenyl)-1H-1,2,4-triazol-5-yl]sulfanyl}-3-(1,1,1-triphenyl-λ⁵-phosphanylidene) succinate 3a

2.1.2 Diethyl-2-{[3-(2-fluorophenyl)-1H-1,2,4-triazol-5-yl]sulfanyl}-3-(1,1,1-triphenyl-λ⁵-phosphanylidene) succinate 3b

2.1.3 Dimethyl-2-{[3-(2-fluorophenyl)-1H-1,2,4-triazol-5-yl]sulfanyl}-3-(1,1,1-triphenyl-λ⁵-phosphanylidene) succinate 3c

2.1.4 Dimethyl-2-{[3-phenyl-1H-1,2,4-triazol-5-yl]sulfanyl}-3-(1,1,1-triphenyl-λ⁵-phosphanylidene) succinate 3d