2-(BROMOMETHYL)-2-PHENYL-1,3-DIOXOLANE

General procedure: Magnesium ribbon (295 mg, 12.2 mmol) was chemically polished by the following sequential washes: 6% aqueous HNO3, H2O, EtOH and anhydrous ether. Washed pieces were activated in a 2% I2 solution in anhydrous THF for 2 minutes then rinsed with anhydrous THF. Activated magnesium was placed under argon atmosphere in anhydrous THF (5 mL), catalytic dibromoethane (2 drops) was added and a solution of a-brominated dioxolane (11.0 mmol) in anhydrous THF (10 mL) was added under argon atmosphere. The reaction was initiated by warming with a paint burner and gentle reflux was maintained by continuous addition of the a-brominated dioxolane solution. The mixture was stirred at 50C for 1 h after addition was complete, and NEt3 (4.66 mL, 33.1 mmol) was added under argon atmosphere. The mixture was then stirred at room temperature for 1h and cooled to 0C. A solution of BzCl (1.708 g, 12.2 mmol) in anhydrous THF (10 mL) was added under argon atmosphere. The mixture was stirred at room temperature overnight and poured into CH2Cl2 (300 mL). The mixture was washed with water (2 x 100 mL), and the combined aqueous layers were extracted with CH2Cl2 (50 mL). Combined organic layers were washed with brine (2 x 100 mL), dried over MgSO4, filtered, and evaporated down under reduced pressure. The crude oil was purified by flash chromatography using a mixture of cyclohexane and ethyl acetate (4-12% ethyl acetate) as eluent to give the hydroxy-protected vinyl ethers as colorless or pale yellow oils.A two-necked round bottomed flask (100 ml) fitted with a Dean-Stark apparatus and reflux condenserwas charged with 2?-bromoacetophenone (50 g, 251.2 mmol), ethylene glycol (17 ml, 304 mmol), p-toluene sulfonic acid (2.4 g, 12.5 mmol) and toluene (250 ml). The reaction mixture was refluxedfor 8 h till maximum amount of water was distilled out azeotropically. Toluene was distilled out under reduced pressure, residue was dissolved in water, extracted withethyl acetate (3 x 150 ml) and organic layer was dried to yield a colorless solid which was recrystallized from hexane-ethyl acetate mixture(55 g, 90 %)[1]. 1H NMR (CDCl3)delta:3.67 (s, 2H, -CH2Br), 3.88-3.96 (m, 2H, -OCH2CH2O-), 4.17-4.25 (m, 2H, -OCH2CH2O-), 7.34-7.40 (m, 3H, C6H5), 7.50-7.53 (m, 2H, C6H5);13C{1H} NMR (CDCl3) delta: 38.4 (-CH2Br), 65.9 (-OCH2CH2O-), 107.3 (-C(OCH2CH2O)-), 126.1, 128.4, 128.9, 139.7 (C6H5).General procedure: A mixture of 2 mmol of substrate, and 4 mL ethylene glycol was stirred for 5 min, and then 2.4 mmol of DBDMH or 4.6 mmol of NBS was added by 5 times in one hour, and the mixture was stirred 24 h at room temperature. Afterward, the mixture was extracted with ether (10 mL × 3). The combined organic layer was washed twice by water (20 mL), and dried over anhydrous Na2SO4. After filtration, the solvent was removed under reduced pressure, and the residual was treated with alumina chromatography (Petroleum ether/AcOEt=20/1, V/V) to generate the product.

Molecular Weight:243.10
XLogP3:1.9
Hydrogen Bond Acceptor Count:2
Rotatable Bond Count:2
Exact Mass:241.99424
Monoisotopic Mass:241.99424
Topological Polar Surface Area:18.5
Heavy Atom Count:13
Complexity:160
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes