1,2‐Oxaphosphole Oxides and Benzo Derivatives

Abstract image [53314‐66‐2] C 4 H 9 O 2 P 2‐methyl‐1,2‐oxaphospholane oxide (MW 120.09) InChI =  1S/C4H9O2P/c1‐7(5)4‐2‐3‐6‐7/h2‐4H2,1H3 InChIKey =  OSNNATVBPNXCAF‐UHFFFAOYSA‐N (reagent used as an electrophilic component mainly through ring‐opening reaction) Physical Data: bp 87 °C (0.15 mmHg). 88–90 °C (0.2 mmHg). Solubility: highly soluble in various aprotic organic solvents, including acetonitrile, dichloromethane, tetrahydrofuran, and pyridine. Form Supplied in: colorless liquid. Analysis of Reagent Purity 1 : 1 H nuclear magnetic resonance (NMR) (CDCl 3 ) 1.60 ppm (d, 3 H ), 1.75–2.55 (m, 4 H ), 3.80–4.55 (m, 2 H ). Preparative Methods: the title reagent can be prepared by the following procedure 1 : i ‐butyl 3‐acetoxypropyl methylphosphinate (200 g, 0.85 mol) was heated to 65–70 °C in a methanol solution of hydrogen chloride (400 mL, 0.68 M). During this process, methyl acetate was azeotropically distilled off from the reaction mixture with methanol. After 4–5 h, the solvent was removed under vacuum, and the residue was dried under vacuum at 50 °C. The crude mixture, which was mainly contaminated by i ‐butyl (3‐hydroxypropyl)‐methylphosphinate, was distilled under reduced pressure, affording the title product (100 g) in 98.5% yield. Purification: distilled under reduced pressure. Handling, Storage, and Precautions: the title reagent is stable under the specified storage temperature. Store in a well‐ventilated place. Keep container tightly closed. Toxicity: H302 Harmful if swallowed; H312 Harmful in contact with skin; H315 Causes skin irritation; H319 Causes serious eye irritation; H332 Harmful if inhaled; H335 May cause respiratory irritation; H373 May cause damage to organs through prolonged or repeated exposure. image [16324‐19‐9] C 9 H 11 O 2 P 2‐phenyl‐1,2‐oxaphospholane oxide (MW 182.16) InChI =  1S/C9H11O2P/c10‐12(8‐4‐7‐11‐12)9‐5‐2‐1‐3‐6‐9/h1‐3,5‐6H,4,7‐8H2 InChIKey =  QQOVFFWBFBOMCS‐UHFFFAOYSA‐N Physical Data: mp 69 °C. bp 142 °C (0.2 mmHg). Solubility: not known. Form Supplied in: white solid. Analysis of Reagent Purity: 1 H NMR (CDCl 3 ) 7.87–7.78 (m, 2 H ), 7.64–7.56 (m, 1 H ), 7.55–7.46 (m, 2 H ), 4.66 (m, 1 H ), 4.48–4.46 (m, 1 H ), 2.52–2.21 (m, 3 H ), 2.07–1.95 (m, 1 H ); 13 C (CDCl 3 ) 132.6 (d, J PC  = 11.7 Hz), 131.5 (d, J PC  = 10.6 Hz), 128.7 (d, J PC  = 13.2 Hz), 70.6 (d, J PC  = 4.8 Hz), 25.7 (d, J PC  = 82.5 Hz), 24.5 (s). The quaternary carbon of the phenyl ring was not detected; 31 P NMR (CDCl 3 ) 54.5. Preparative Methods: the title reagent can be prepared by the following procedure 2 : under an inert atmosphere, dimethyl phenylphosphonite (6.0 g, 0.035 mol, 1 equiv) and 1,3‐dibromopropane (35.6 g, 0.17 mol, 4.86 equiv) were placed in a round‐bottom flask equipped with a condenser. The reaction mixture was heated to 150 °C for 2 h. The excess of 1,3‐dibromopropane was removed under vacuum, and the mixture was purified by flash chromatography (CHCl 3 ), affording 1.34 g of the title compound (21% yield). Purification: purified by chromatography. Handling, Storage, and Precautions: not known. Toxicity: not known. image [1193‐39‐1] C 5 H 11 O 3 P 2‐ethoxy‐1,2‐oxaphospholane oxide (MW 150.11) InChI =  1S/C5H11O3P/c1‐2‐7‐9(6)5‐3‐4‐8‐9/h2‐5H2,1H3 InChIKey =  KBESTWHNVGVDHD‐UHFFFAOYSA‐N Physical Data: bp 72–74 °C (0.01 mmHg). d  = 1.1975. Form Supplied in: colorless liquid. Analysis of Reagent Purity: 1 H NMR (CDCl 3 ) 4.15 (m, 4 H ), 2.26 (m, 2 H ), 1.85 (m, 2 H ), 1.32 (t, 3 H ). 31 P NMR (CD 3 OD + CCl 4 ) 35.1. Preparative Methods: the title reagent can be prepared by the following procedure 3 : a mixture of 3‐bromopropylphosphonate (2.6 g, 0.01 mol) and NaBr (1.0 g, 0.01 mol) in N , N ‐dimethylformamide (DMF) (7 mL) was refluxed for 5 h. The reaction mixture was concentrated under vacuum, and the residue was dissolved in water (30 mL) and extracted with chloroform (30 mL). The organic phase was dried over Na 2 SO 4 and concentrated under vacuum. The residue was distilled, affording a colorless liquid 1.2 g (80% yield). Other preparative methods for analogues can be found in the corresponding references. 4 Purification: distilled under reduced pressure. Handling, Storage, and Precautions: not known. Toxicity: not known.