Trimethylsilyl bromide acid halide synthesis

Many functionalized allylic halides tolerate the reaction conditions, allowing more straightforward syntheses of useful intermediates, including 2-trimethylsilyl-2-propenyl iodide, 2-bromomethyl-2-propenyl bromide, and 2-bromomethylacrylic acid. The derivative from 2-bromomethylacrylic acid has been applied to carbohydrate synthesis, including A acetylneuraminic acid. Of particular interest is the intramolecular alkylation for ring expansion."... 

Formation and Reaction of the Trimethylsilyl Ester of Squaric Acid. The most common method employed in the synthesis of squarate esters uses expensive silver nitrate and goes through the explosive disilver salt of squaric acid. It was conceived that sUyl esters of squaric acid 38 may be considered as silyl enol ethers that can undergo Si-O cleavage in the presence of a suitable fluoride source and that O-alkylation may be affected using electrophilic halides. Upon preparation of thebis(trimethyl-silyl) squarate 39 using BSA and reaction in situ with p-methylbenzyl bromide in the presence of a fluoride source, the desired benzyl squarate 40 was obtained in about 50% overall yield (eq 42). ... 

---