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Benzopyrans
About: Benzopyrans is a research topic. Over the lifetime, 694 publications have been published within this topic receiving 8830 citations.
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TL;DR: In this article , a facile method for the synthesis of 2,2-disubstituted-2H-1-benzopyrans from easily accessible tertiary propargylic alcohols and phenolic derivatives is described using a sulfonated tetraphenylethylene-based hypercrosslinked polymer (THP-SO3H) as the heterogeneous organocatalyst.
TL;DR: Glycals react smoothly with o-hydroxybenzaldehydes and trimethyl orthoformate in the presence of a catalytic amount of scandium triflate under mild reaction conditions to afford the corresponding cis-annelated pyranobenzopyrans in good yields with high diastereoselectivity as discussed by the authors.
Abstract: Glycals react smoothly with o-hydroxybenzaldehydes and trimethyl orthoformate in the presence of a catalytic amount of scandium triflate under mild reaction conditions to afford the corresponding cis-annelated pyranobenzopyrans in good yields with high diastereoselectivity.
23 Apr 2015
TL;DR: The bridged chiral benzopyrans were strategically ring opened via acetolysis to yield either galactose based chromenes or chromans, depending on the reaction conditions as mentioned in this paper.
Abstract: The bridged chiral benzopyrans were strategically ring opened via acetolysis to yield either galactose based chromenes or chromans, depending on the reaction conditions. A proposal relating to the mechanism of this selective ring opening acetolysis is discussed. The benzopyrans (chromenes, chromans and bridged chiral benzopyrans) were de-acetylated via triethyl amine catalysed transesterification. Interestingly, the chromenes did not yield the anticipated hydrolysis product (triol) but a new class of bridged chiral benzopyrans which were a result of intramolecular oxa-Michael addition. A chromene that formed during the selective ring opening of the bridged chiral benzopyrans was employed to develop a method for the synthesis of a carbohydrate derived oxepane. The oxepane synthesis was achieved, albeit in the face of numerous challenges from side reactions. The difficulties encountered in the synthesis are discussed...