Dimethyl-1,3-dioxanes

Cychc carbonates are prepared in satisfactory quaUty for anionic polymerization by catalyzed transesterification of neopentyl glycol with diaryl carbonates, followed by tempering and depolymerization. Neopentyl carbonate (5,5-dimethyl-1,3-dioxan-2-one) (6) prepared in this manner has high purity (99.5%) and can be anionically polymerized to polycarbonates with mol wt of 35,000 (39). 

Dimethyl-1,3-dioxolane, 326 frans-1,2-Cyclohexanediol Ketal, 327 frans-4,6-Dimethyl-1,3-dioxane, 327... 

The conjugate addition of alkylcupratcs to (E)- and (Z)-(4S)-4-(5,5-dimethyl-1,3-dioxan-2-yl)-2-pentenal (entries 13 and 14) gave predominantly the. yjYi-adduct10. The stereogenic center in these substrates exists at the y-position, but the oxygen atom is located at the (5-position. 

II) tert-Butyl(4i ,6i )-2-[6-(2-aminoethyl)-2.2-dimethyl-1.3-dioxan-4-yl] acetate... 

A. 5-(1-Hydroxyethylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione. A flame-dried, 500-mL, three-necked, round-bottomed flask is equipped with a stir bar, nitrogen inlet adapter, and a pressure-equalizing addition funnel fitted with a rubber septum. The flask is charged with 22.0 g of Meldrum s acid dissolved in 153 mL of methylene chloride, and 24.8 mL of pyridine (Note 1), and the mixture is cooled to -25°C (Note 2). A mixture of 18.3 mL of methylene chloride and 13.1 mL of acetyl chloride is slowly added to the reaction mixture via the addition funnel over 1 hr (Note 3). After the addition of the acetyl chloride is complete, the reaction is slowly warmed over 3 hr to... 

A stirred solution of 2-(2 -iodo-2 -methanesulfonyl)ethyl-2-methyl-5.5-dimethyl-1,3-dioxane (76mg, 0.21 mmol) in dry THF (8 ml) at -78°C... 

Dimethyl-1,3-Dioxane-4,6-dione (Meldrum s Acid) Malonic acid, cyclic isopropylidene ester (8) 1,3-Dioxane-4,6-dione, 2,2-dimethyl- (9) (2033-24-1) Ethylenediammonium diacetate 1,2-Ethanediamine diacetate (9) (38734-69-9) (R)-Citronellal 6-Octenal, 3,7-dimethyl-, (R)-(+)- (8,9) (2385-77-5)... 

Dimethyl-1,3-dioxane-4,6-dione (Meldrum s acid) 0.72 g, 5.0 mmol may cause eye, skin, and respiratory tract irritation... 

D-6-0-[2-(5,5-Dimethyl-1,3-dioxan-2-yl)ethyl]-2,3-O-isopropylidene-myo-inositol l,4,5-tris(dibenqylphosphate) ... 

To an ice-cooled solution of 5-(2-hydroxyethyl)-2,2-dimethyl-l,3-dioxan (1.92 g, 12 mmol) and carbon tetrabromide (7.96 g, 24 mmol) in dimethylformamide (100 ml) triphenylphosphine (6.30 g, 24 mmol) was added and the solution was left at 4°C overnight. To this solution methanol (20 ml) was added and the solvent was then evaporated under reduced pressure. The residue was purified by column chromatography on silica gel, eluting with hexane-acetone (12 1) to afford 5-(2-bromoethyl)-2,2-dimethyl-1,3-dioxan as a clear colourless liquid (0.89 g, 40%). 

V,5S)-5-Amino-4-phenyl-2,2-dimethyl-l,3-dioxane and (4i ,5i )-5-amino-(4 -biphenyl)-2,2-dimethyl-1,3-dioxane were synthesized and employed as chiral solvating agents for the ee determination of compounds bearing an acidic proton by means of NMR spectroscopy (99TA323). Based on the rigid conformation of the two amines, they are... 

MELDRUM S ACID 2,2-DIMETHYL-1,3-DIOXANE-4,6-DIONE MALONIC ACID, CYCLIC ISOPROPYLIDENE ESTER 1,3-DIOXANE-4,6-DIONE, 2,2-DIMETHYL- (2033-24-1), 67, 170 69, 33 p-Mentha-6,8-dien-2-one (6485-40-1), 66, 13... 

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