L-Bromo-3-chloro-2,2-dimethoxypropane

A. 2-( Bromomethyl)- .-( ehloromethyD-1, -dioxane. A 100-mL, round-bottomed flask is equipped with a 10-mL Dean-Stark apparatus and a condenser. The flask is charged with 30.0 g (0.138 mol) of l-bromo-3-chloro-2,2-dimethoxypropane (Note 1), 10.0 mL (0.138 mol) of 1,3-propanediol (Note 2), and 3 drops of concentrated sulfuric acid. The resulting solution is heated (bath temperature 140°C) for 8 hr (Note 3) with distillative removal of methanol (ca. 11 mL). The mixture is allowed to cool to room temperature and the crude product is partitioned in 150 mL of pentane and 40 mL of water. The... 

Dimethoxycyclopropene (3). Baucom and Butler have reported a relatively simple synthesis of 3,3-dimethoxycyclopropcne (3) from 2,3-dichloropropene (1). This compound is converted into l-bromo-3-chloro-2,2-dimethoxypropane (2) by treatment... 

The reaction of l-bromo-3-chloro-2,2-dimethoxypropane with potassium amide in liquid ammonia at — 50 C provides an efficient route to 3,3-dimethoxycyclopropene (1). ... 

Bromo-3-chloro-2,2-dimethoxypropane 2-Propanone, l-bromo-3-chloro-,... 

The condensation of 2-(5-bromo-4-chloro-2-hydroxybenzoyl)pyridine 506 in a sealed tube with ammonia and acetone proved a convenient route to 2//-l,3-benzoxazine derivative 225 via the imine intermediate 507 <1996CPB734>. The yield was improved considerably and a closed vessel was not required for the reaction when the ammonia was prepared in situ from NH4I and piperidine, and 2,2-dimethoxypropane was used instead of acetone (Scheme 95). The improved method was extended to the preparation of other 2,2-disubstituted-2//-l,3-benzoxazine derivatives <2001T7501>. 

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