The expedient access to bromo-pyridine carbaldehyde scaffolds using gem-dibromomethyl intermediates
摘要:
A simple, efficient, and general two-step synthesis to bromo-pyridine carbaldehyde scaffolds is described. This direct route involves sequential reactions employing the dibromination of bromo-picolines followed by hydrolysis using an aqueous solution of calcium carbonate. Bromo-pyridine carbaldehyde scaffolds 1-7 were obtained in good overall yield. Bromo-dibromomethyl-pyridine intermediates have been isolated and characterized. (c) 2005 Elsevier Ltd. All rights reserved.
[GRAPHICS]The syntheses of reduced-symmetry deep-cavity cavitands by two-stage stereoselective bridging with substituted benzal bromides is reported. Conditions for the optimal formation of the trisbridged derivatives were readily established. However, it was not possible to determine conditions which selectively promoted formation of either one of the two bisbridged species, or the monobridged compound, above the other products. A comparison of yields for A/B bisbridged derivatives verses A/C bisbridged derivatives may indicate that the one-pot formation of deep-cavity cavitands occurs primarily through the former species.
Alternative approach to the free radical bromination of oligopyridine benzylic-methyl group
作者:Sébastien Bedel、Gilles Ulrich、Claude Picard
DOI:10.1016/s0040-4039(02)00127-2
日期:2002.2
influence of three solvents on the photobromination of two picolines. It shows that dichloromethane and benzene are better solvents than the classical carbon tetrachloride. The obtention of a good freeradicalbromination is described using aqueous biphasic media.