Improved Direct Acetalisation for (Strained) Cyclic Acetals

New and Efficient Chiral Selenium Electrophiles

“…Melting points are uncorrected. Alkenes 12,15,17,and 19 were prepared as reported previously. [10] GP1: General procedure for the addition of selenium electrophiles to styrene: The diselenide (0.1 mmol) was dissolved in dry diethyl ether (4 mL) under argon, cooled to À 78 8C, and treated with bromine (0.11 mmol, 0.11 mL of a 1m solution in CCl 4 ).…”

“…H),7.06 (d,J 8.5 Hz,2 H;arom. H); 13 C NMR (75 MHz,CDCl 3 ): d 17.3 (t, 2 C), 29.0 (t, 2 C), 29.3 (t, 2 C), 55.6 (q, 2 C), 56.3 (q, 2 C), 74.7 (d, 2 C), 97.4 (t, 2 C), 111.1 (d, 2 C), 122.5 (s, 2 C), 130.0 (s, 2 C), 131.3 (d, 2 C), 140.5 (s, 2 C), 158.6 (s, 2 C); IR (CHCl 3 ): n Ä 3005, 2938, 2838, 1472, 1440, 1265, 1149, 1094, 1031MS (70 eV, EI): m/z (%): 602 (8) [M ], 540 (15), 478 (12), 319 (7), 255 (80), 240 (69), 225 (10), 195 (7), 160 (84), 145 (72), 128 (58), 115 (80), 102 (11) 3666,3382,3005,2937,2838,1570,1464,1431,1136,1103,1052,1016 3666,3382,3005,2937,2838,1570,1464,1431,1136,1103,1052,1016 3006, 2934, 1440, 1157, 1104, 1035…”

“…(R)-4-(2-Bromphenyl)- [1,3]dioxolane: [15] (R)-1-(2-Bromophenyl)-1,2-ethanediol (9; 450 mg, 2.07 mmol), paraformaldehyde (200 mg, 6.2 mmol) and p-toluenesulfonic acid (5 mg, 0.025 mmol) were dissolved in dry ethanol (1.5 mL) and benzene (7.5 mL) and stirred at 60 8C for 1 h. The solvent was distilled off and the mixture heated to 200 8C in the Kugelrohr oven to distill off the product as a colorless liquid. Yield: 419 mg (88 % (75); HRMS calcd for C 9 H 9 BrO 2 [M ] 227.9786, found 227.9798.…”

Polymerization of cyclic monomers, 3. Synthesis, radical and cationic polymerization of bicyclic 2‐methylene‐1,3‐dioxepanes

“…In a 250-mL flask with water separator a mixture of 21,l g (93 mmol) 4, a fivefold molar excess of the corresponding aldehyde or ketone, 70 mL methylene chloride or chloroform, and 0,2 g p-toluenesulfonic acid were heated until the water separation was finished. After evaporation of the solvent under atmospheric pressure the residue was distilled over a short Vigreux column in vacuum: : 6 = 24,9,25,0,27,2 and 27,6 (CH,),31,l and 31,3 (CH2Br), 66,6 2965 cm-' (m). CH Br), 3,66-4,45 (m; 6H, CH2-O/>CH-O) and 5,08-$11 (m; 1 H, -HC<).…”

Totality and representation: A history of knowledge management through European documentation, critical modernity, and post‐Fordism

“…( R )‐4‐(2‐Bromphenyl)‐[1,3]dioxolane :15 ( R )‐1‐(2‐Bromophenyl)‐1,2‐ethanediol ( 9 ; 450 mg, 2.07 mmol), paraformaldehyde (200 mg, 6.2 mmol) and p ‐toluenesulfonic acid (5 mg, 0.025 mmol) were dissolved in dry ethanol (1.5 mL) and benzene (7.5 mL) and stirred at 60 °C for 1 h. The solvent was distilled off and the mixture heated to 200 °C in the Kugelrohr oven to distill off the product as a colorless liquid. Yield: 419 mg (88 %); [ α ]$\rm{_{D}^{25}}$ =−58.6 ( c =1.18, CHCl 3 ); 1 H NMR (300 MHz, CDCl 3 ): δ =3.67 (dd, J =5.9 Hz, J =8.4 Hz, 1 H; OC H HCHO), 4.43 (dd, J =6.9 Hz, J =8.2 Hz, 1 H; OCH H CHO), 5.09 (s, 1 H; OC H HO), 5.30 (s, 1 H; CH H O), 5.31 (t, J =6.4 Hz, 1 H; ArCH), 7.16 (dt, J =1.7 Hz, J =7.7 Hz, 1 H; arom.…”