Method of preparing and method of using tetracarbonyl cyclobutene dihydrate compound

Abstract

A tetracarbonyl cyclobutene dihydrate compound, having a chemical formula (I). ##STR00001## A method of synthesizing the tetracarbonyl cyclobutene dihydrate compound, includes: a synthesis step, a separation step, and a purification step. The synthesis step includes: collecting and dissolving 0.5728 g of squaric acid, 2.7948 g of ammonium formate, and 0.0480 g of the palladium complex in 100 mL of anhydrous methanol, heating and stirring a resulting mixture to reflux for 48 hrs, and stopping the reaction. The separation step includes: performing column chromatography analysis on reaction products according to a volume ratio of dichloromethane to anhydrous methanol of 8:2, to obtain a target product. A method of using the tetracarbonyl cyclobutene dihydrate compound, includes: using tetracarbonyl cyclobutene dihydrate compound as a catalyst in addition reaction between ethyl pyruvate and nitromethane, where a conversion rate of ethyl pyruvate reaches 96.1%.

Claims

1. A tetracarbonyl cyclobutene dihydrate compound, prepared by reacting squaric acid with ammonium formate, and having a chemical formula (I): ##STR00005##

2. The tetracarbonyl cyclobutene dihydrate compound of claim 1, prepared into a form of a crystal, wherein when being diffracted with a MoKα ray, which is monochromated by a graphite monochromator and has a wavelength of λ=0.71073 Å, in an ω-θ scanning mode on an Oxford X-ray single crystal diffractometer at a temperature of 293(2)K, the crystal of the tetracarbonyl cyclobutene dihydrate compound belongs to a monoclinic system, C 2/c, and has unit cell dimensions as follows: a=3.70690(10) Å alpha=90 deg.; b=7.2586(3) Å beta=97.897 deg.; and c=11.9274(5) Å gamma=90 deg.

3. A method of synthesizing the tetracarbonyl cyclobutene dihydrate compound of claim 1, comprising: a synthesis step, a separation step, and a purification step; wherein the synthesis step comprises: collecting and dissolving 0.5728 g of squaric acid, 2.7948 g of ammonium formate, and 0.0480 g of a palladium complex in 100 mL of anhydrous methanol, heating and stirring a resulting mixture to reflux for 48 hrs, and stopping the reaction; and the separation step comprises: performing column chromatography analysis on reaction products according to a volume ratio of dichloromethane to anhydrous methanol of 8:2, to obtain a target product.

4. A method of using the tetracarbonyl cyclobutene dihydrate compound of claim 1, as a catalyst in addition reaction between ethyl pyruvate and nitromethane; wherein a conversion rate of ethyl pyruvate reaches 96.1%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present application is described hereinbelow with reference to accompanying drawings, in which the sole FIGURE is an X-ray diffraction analysis chart of compound I.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(2) To further illustrate the present application, experiments detailing a method of preparing and a method of using a tetracarbonyl cyclobutene dihydrate compound are described below. It should be noted that the following examples are intended to describe and not to limit the present application.

(3) Preparation of a palladium complex is described as follows.

Example 1. Preparation of Chiral Palladium Complex

(1) Preparation of [1,4-(4R)-diisopropyl-2-oxazolinyl]benzene

(4) 1.4054 g (10.64 mmol) of anhydrous ZnCl.sub.2, 40 mL of chlorobenzene, 5.0236 g (39.2 mmol) of 1,4-dicyanobenzene, 16.2075 g of L-valinol were added in a 100 mL two-neck flask under an anhydrous and oxygen-free condition. A resulting mixture was refluxed at a high temperature for 60 hrs. The reaction was stopped, and then a solvent was removed under a reduced pressure to obtain a residue. After that, the residue was dissolved in water and extracted with CHCl.sub.3 (20 mL×2). An organic phase was dried by anhydrous sodium sulfate, rotatory filtration was then performed to remove the solvent, and a crude product was performed with column chromatography with petroleum ether/dichloromethane (4:1) to obtain a light green viscous liquid with a yield of 52%. An obtained white crystal has a melting point of 48-50° C., [a].sup.5.sub.D=+111.9° (c=0.429, CHCl3); .sup.1H NMR (500 MHz, CDCl.sub.3, 27° C.), δ (ppm)=7.97 (s, 4H), 4.39-4.43 (t, 3.18 Hz, 1H), 4.09-4.15 (m, 2H), 1.85-1.86 (m, 1H), (d, J=6.24 Hz, 6H), 0.86-0.96 (d, J=6.24 Hz, 6H). .sup.13C NMR 18.13, 19.03, 32.85, 70.26, 72.76, 128.10, 128.16, 130.32, 162.82. IR: 3273, 2976, 2960, 2932, 2889, 2869, 1643, 1512, 1469, 1408, 1382, 1366, 1350, 1320, 1296, 1276, 1214, 1180, 1108, 1077, 1047, 1014, 971, 955, 900, 891, 838, 726, 698, 675, 659, 540. HRMS (EI): m/z (%): calcd for C.sub.18H.sub.24N.sub.2O.sub.2: 300.1838; found: 300.1833.

(2) Preparation of bis{[1,4-(4S)-diisopropyl-2-oxazolinylbenzene]palladium Chloride} Complex

(5) 1.5603 g (4.92 mmol) of palladium chloride, 1.0435 g (3.48 mmol) of 1,4-(4R)-diisopropyl-2-oxazolinylbenzene, and 30 mL of chlorobenzene were added to a 100 mL two-neck flask under an anhydrous and oxygen-free condition. A resulting mixture was refluxed at a high temperature for 48 hrs. The reaction was then stopped, and a solvent was removed under a reduced pressure. A resulting residue chloroform and ethanol were dissolved and naturally volatized to obtain a crystal of a reddish-brown complex, with a yield of 92%. m.p.: >200° C., [a].sup.5.sub.D=+512.8° (c 0.0564, CH3OH); .sup.1H NMR (600 MHz, CDCl.sub.3), δ′ ppm 8.81 (s, 8H, ArH), 4.61-4.63 (m, 4H, CH×4), 4.53 (t, J=9.6 Hz, 4H, CH×4), 4.44 (t, J=8.5 Hz, 4H, CH×4), 3.07-3.10 (m, 4H), 1.18 and 1.15 (dd, J=6.7, 7.2 Hz, 24H, CH3×4); .sup.13C NMR (150 MHz, CDCl.sub.3) δ ppm 166.8, 130.1 (×2), 129.3, 72.0, 69.1, 30.7, 19.0, 15.6; ν.sub.max (cm.sup.−1) 3487, 3049, 2957, 2929, 2872, 1642, 1609, 1572, 1509, 1480, 1464, 1416, 1379, 1331, 1288, 1246, 1178, 1141, 1123, 1099, 1045, 1018, 959, 933, 899, 854, 804, 770, 722, 693, 438. Elemental analysis: C.sub.36H.sub.48N.sub.4Cl.sub.4O.sub.4Pd.sub.2: Test value: C, 45.26%, H, 5.06%, and N, 5.86%; and theoretical value: C, 45.32%, H, 5.24%, and N, 5.48%.

Example 2 Preparation of Tetracarbonyl Compound

(6) 0.5728 g of squaric acid, 2.7948 g of ammonium formate, and 0.0480 g of the palladium complex were collected and dissolved in 100 mL of anhydrous methanol. A resulting mixture was heated and stirred to reflux for 48 hrs, and the reaction was then stopped. Reaction products were performed with column chromatography analysis according to a volume ratio of dichloromethane to anhydrous methanol of 8:2 to obtain 0.3481 g of a target product, the yield was 68%, and a melting point of the target product was >250° C. Elemental analysis: (C4H4O6); theoretical value: 32.45% of C and 2.72% of H; and measured value: 32.67% of C and 2.68% of H; HRMS: Theoretical value: 148.0008; Measured value: 148.0012; 13CNMR (125 MHz, CDCl3, 27° C.): 196.5, IR (KBr): 3019, 2854, 2177, 1652, 1500, 1418, 1364, 1088.

(7) TABLE-US-00001 Crystal data of the compound Empirical formula C4H4O6 Molecular weight 148.07 Temperature 291(2) K wavelength 0.71073 Å Crystal system, space group Monoclinic, C 2/c Unit cell dimensions a = 3.70690(10) Å alpha = 90 deg. b = 7.2586(3) Å beta = 97.897 deg. c = 11.9274(5) Å gamma = 90 deg. volume 317.71 (2) Å.sup.3 charge density 2 , 1.548 Mg/m.sup.3 Absorption correction parameter 1.376 mm.sup.−1 Number of electrons in a unit cell 152.0 Crystal size 0.220 × 0.180 × 0.170 mm Theta range 14.322 to 139.478 Collection range of HKL's indicator −3 <= h <= 4, −8 <= k < 8, −14 <= 1 <= 14 Reflections collected/unique 998/583 [R(int) = 0.0162] Completeness to theta = 30.5 1.098% Absorption correction method Multi-layer scanning Maximum and minimum 0.7456 and 0.5760 transmittance Refinement method Full-matrix least-square on F.sup.2 Data number/restraint number/ 583/2/54 parameter number Refinement method 1.098 Uniformity factor of diffraction point R.sub.1 = 0.0678, wR.sub.2 = 0.1678 Observable diffraction fit factor R.sub.1 = 0.0702, wR.sub.2 = 0.1693 Largest peak and hole on the 0.610 and −0.55 e.Å.sup.−3 difference Fourier diagram

(8) TABLE-US-00002 TABLE 4 Typical bond length data of crystal Bond Lengths for LM-200915. Atom Atom Length/Å Atom Atom Length/Å O1 C2 1.252(4) C1 C2 1.465(4) O2 C1 1.257(4) C2 C1.sup.1 1.462(4) C1 C2.sup.1 1.462(4)

(9) TABLE-US-00003 Bond angle data of crystal Atom Atom Atom Angle/° Atom Atom Atom Angle/° O2 C1  C2.sup.1 133.8 (3) O1 C2  C1.sup.1 133.7 (3) O2 C1 C2 136.1 (3) O1 C2 C1 136.4 (3)  C2.sup.1 C1 C2  90.2 (2)  C1.sup.1 C2 C1  89.8 (2)

Example 3 Application in Henry Reaction

(10) ##STR00004##

(11) 0.05 mmol of the compound (I) was placed in a 25 mL flask, and 1 mL tetrahydrofuran, 0.3 mL nitromethane and 0.5 mmol of ethyl pyruvate were added sequentially to the flask, a resulting mixture were stirred for reaction for 20 hrs. Samples were taken for .sup.1HNMR detection. The conversion rate was 96.1%; .sup.1H NMR (600 MHz, CDCl3): δ) 4.86 (d, J=13.8 Hz, 1H), 4.58 (d, J=13.8 Hz, 1H), 4.34 (m, 2H), 3.85 (s, 1H), 1.46 (s, 3H), 1.33 (t, J=7.2 Hz, 3H). 13 C NMR (150 MHz, CDCl 3): δ=173.4, 80.9, 72.4, 63.0, 23.8, 13.9.