Inspired by the chemistry and biology of hexahydroxanthones, herein we report an organocatalytic Michael-Michael-Aldol-decarboxylation reaction that provides efficient access to biologically interesting fully substituted hexahydroxanthones bearing six contiguous stereogenic centers from readily accessible materials in acceptable yields (up to 63%) and excellent stereoselectivities (up to 10 : 1 dr and >99% ee). In other words, the reaction efficiently produces three chemical bonds and up to six vicinal stereogenic centers in a one-pot operation. In particular, to our knowledge, this is an asymmetric organocatalytic strategy enabling the first construction of six vicinal stereogenic centers on non-spirocyclic hexahydroxanthone frameworks.
View Article and Find Full Text PDFObjective: To observe the effect of round magnetic needle tapping along meridians on the back plus acupuncture at "Qi Shen Zhen"(including Shenting [GV24], Benshen [GB13], Sishenchong [EX-HN1]), and Baihui (GV20), Shenmen (HT7) on gastrointestinal function, daily living activities and anxiety status in post-stroke anxiety disorder (PSAD) patients.
Methods: Fifty-seven PSAD patients were randomly divided into acupuncture group (28 cases) and medication group (29 cases). On the basis of routine treatment and physical therapy, patients of the acupuncture group were treated by applying round magnetic needle to mildly tapping the second line→the first line of the Bladder Meridian→Jiaji acupoints→Governor Meridian on the back from outside to the inside in sequence for 20 min, followed by needling GV24, GV20, GB13, EX-HN1 and HT7, respectively, with the needles retained for 30 min after one minute's twisting.
A set of cascade benzannulations of readily accessible chromone-3-carboxaldehydes and γ-nitroaldehydes for synthesizing biologically relevant 2-hydroxybenzophenones has been developed. The cascade was found to provide a transition-metal-free strategy for synthesizing 2-hydroxybenzophenones in acceptable yields (up to 57%).
View Article and Find Full Text PDFThe first example of a bifunctional donor-donor 3C synthon in situ from activated methine (methyleneindolinone and methylenebenzofuranone) with nitromethane through a [2+1] Michael addition, which further directed the following organocascade Michael/Henry cycloaddition reaction in a one-pot operation is developed, serving as a fruitful strategy for facile access to optically active and structurally diverse hexahydroxanthones with up to six contiguous stereocenters, including a quaternary one. A series of diversely functionalized products are smoothly obtained with up to 76% yield, >20 : 1 d.r.
View Article and Find Full Text PDFWe report the first asymmetric iminium ion catalysis-enabled cascade cycloaddition reaction of bifunctional chromone-oxindole synthons and α,β-unsaturated aldehydes. This allowed one quaternary and four tertiary contiguous stereogenic centers to be constructed in a single operation. A range of spirooxindole-hexahydroxanthone molecules are obtained with up to 62% yield, >20 : 1 dr and >99% ee.
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