A practical sequence involving a noncryogenic stereospecific boronate rearrangement followed by a robust formylation with an in situ generated DCM anion has been developed for the asymmetric construction of an all-carbon quaternary stereogenic center of a FLAP inhibitor. The key boronate rearrangement was rendered noncryogenic and robust by using LDA as the base and instituting an in situ trapping of the unstable lithiated benzylic carbamate with the boronic ester. A similar strategy was implemented for the DCM formylation reaction. It was found that the 1,2-boronate rearrangement for the formylation reaction could be temperature-controlled, thus preventing overaddition of the DCM anion and rendering the process reproducible. The robust stereospecific boronate rearrangement and formylation were utilized for the practical asymmetric synthesis of a chiral quaternary FLAP inhibitor.

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A practical noncryogenic process for the Aggarwal stereospecific boronate rearrangement with chiral secondary benzylic carbamates has been developed. The use of LDA instead of sec-BuLi combined with an in situ trapping of the unstable lithiated carbamate was critical to success. Furthermore, this new process increased the substrate scope to include the versatile aryl iodide and bromide substrates. The methodology was applied to a diverse array of substrates and was demonstrated on multikilogram scale.

A method is described by which small amounts of water in some organic liquids, down t o 10 p.p.m. can be reliably determined. The method is rapid and simple to operate.

The indicators sulphonazo 111, dimethylsulphonazo I11 and carboxyarsenazo have been compared for the determination of sulphur by flask combustion or by furnace-tube combustion. Carboxyarsenazo is preferred , the optimum conditions for its use being a 2 + 1 acetonewater solution buffered with pyridine and perchloric acid.

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The method involves digesting the sample with a wet combustion mixture, aspirating the evolved gases by a slow stream of air through a heated silica tube containing a silver spiral into an evacuated Buchner flask containing barium hydroxide solution, neutralising the excess of barium hydroxide to thymolphthalein and titrating the precipitated barium carbonate directly