We describe herein an organocatalytic enantioselective approach for the construction of axially chiral sulfone-containing styrenes. Various axially chiral sulfone-containing styrene compounds were ...prepared with excellent enantioselectivities (up to >99% ee) and almost complete E/Z selectivities (>99% E/Z). Furthermore, the axially chiral sulfone-containing styrenes could be easily converted into phosphonic acid and S/P ligands, which could be potentially used as organocatalysts or ligands in asymmetric catalysis.
Graphdiyne oxide (GDO), the oxidized form of graphdiyne (GDY), exhibits an ultrafast humidity response with an unprecedented response speed (ca. 7 ms), which is three times faster than that of ...graphene oxide (GO) with the same thickness and O/C ratio. The ultrafast humidity response of GDO is considered to benefit from the unique carbon hybridization of GDO, which contains acetylenic bonds that are more electron‐withdrawing than ethylenic bonds in GO, consequently giving rise to a faster binding rate with water. This distinctive structure‐based property enables the fabrication of a novel GDO‐based humidity sensor with an ultrafast response speed and good selectivity against other kinds of gas molecules as well as high sensitivity. These properties allow the sensor to accurately monitor the respiration rate change of human and hypoxic rats.
Hybridization matters: Graphdiyne oxide (GDO), the oxidized form of graphdiyne (GDY), exhibits an ultrafast humidity response with an unprecedented response speed (ca. 7 ms), which is three times faster than that of graphene oxide (GO). The acetylenic bond of GDO is more electron‐withdrawing than the ethylenic bond in GO and gives rise to a faster binding rate with water.
A highly diastereo‐ and enantio‐selective method for the asymmetric synthesis of molecules containing helicenes and stereogenic axes was developed based on organocatalysis. Various compounds bearing ...both helical and axial stereogenic elements were obtained in excellent enantioselectivities. The mechanism study revealed that the reaction proceeded through two stages: 1) The first cyclization produces a reaction intermediate containing a stereogenic axis. 2) The dynamic kinetic resolution of helix reaction intermediate following with cyclization generates a helix and another stereogenic axis.
A highly diastereo‐ and enantio‐selective method for the asymmetric synthesis of molecules containing helicene and stereogenic axes was developed based on organocatalysis. Various compounds bearing both helical and axial stereogenic elements were obtained in excellent enantioselectivities.
A highly diastereo- and enantioselective methodology for the asymmetric synthesis of vicinal diaxial styrenes and multiaxis system was achieved by organocatalysis. Various vicinal diaxial styrenes ...and multiaxis systems were obtained in excellent enantioselective manners. The mechanism studies revealed that a new tetra-substituted vinylidene ortho-quinone methide (VQM) intermediate was likely involved and accounted for the excellent enantioselectivity.
We herein demonstrated an efficient method for the atroposelective construction of nine‐membered carbonate‐bridged biaryls through vinylidene ortho‐quinone methide (VQM) intermediates. Diverse ...products with desirable pharmacological features were synthesized in satisfying yields and good to excellent enantioselectivities. In subsequent bioassays, several agents showed considerable antiproliferative activity via the mitochondrial‐related apoptosis mechanism. Further transformations produced more structural diversity and may inspire new ideas for developing functional molecules.
An efficient method for the atroposelective construction of nine‐membered carbonate‐bridged biaryls was achieved through a ring‐expansion process via vinylidene ortho‐quinone methide (VQM) intermediates. This strategy allows the convenient construction of bridged biaryls with broad functional group tolerance under mild conditions. In bioassay studies, several agents showed considerable antiproliferative activity via the mitochondrial‐related apoptosis mechanism.
An organocatalytic enantioselective method for the synthesis of multiple stereoisomers bearing E, Z configurations, stereogenic carbon centers, and axially chiral styrenes is reported. The method ...enabled the rapid construction of a series of stereochemical complexity products with excellent E, Z selectivity, diastereoselectivity (>20:1 dr), and enantioselectivity (up to 96% ee). This method provides an efficient and concise synthesis route of multiple stereoisomers with a wide range of potential applications in organic synthesis.
The enantioselective construction of axially chiral aryl‐naphthopyran skeletons was realized by organocatalytic atroposelective intramolecular 4+2 cycloaddition of in situ generated vinylidene ...ortho‐quinone methides, from 2‐ethynylphenol derivatives, with alkynes. Through this method, the heteroatropisomers were obtained with excellent yields and enantioselectivities. Moreover, a speculative model of the stereochemical outcome is proposed based on preliminary mechanistic studies. The products having various functional groups can be easily transformed into valuable intermediates as either potential ligands or organocatalysts.
Skeleton crew: The enantioselective construction of axially chiral aryl‐naphthopyran skeletons was realized by organocatalytic atroposelective intramolecular 4+2 cycloaddition of in situ generated vinylidene ortho‐quinone methides (VQMs), from 2‐ethynylphenol derivatives, with alkynes. The heteroatropisomers were obtained in excellent yields and enantioselectivities under mild reaction conditions and with good functional‐group tolerance.
An efficient organocatalytic construction of enantioenriched axially chiral 1,4-distyrene 2,3-naphthalene diols through the nucleophilic addition of α-amido sulfone to in situ generated vinylidene ...o-quinone methide is described. The reaction pathway was investigated by isolating reaction intermediates and performing a kinetic resolution process. Axially chiral 1,4-distyrene 2,3-naphthalene diol was used as the chiral ligand for the enantioselective addition of diethylzinc to naphthalene formaldehyde. The preliminary results revealed that these adducts could be potentially used as ligands in asymmetric synthesis.
Described herein is the enantioselective construction of oxygen‐containing 5‐6‐5 tricyclic heterocycles by an organocatalyzed asymmetric 4+2 cycloaddition of vinylidene ortho‐quinone methides and ...benzofurans. According to this methodology, a series of oxygen‐containing 5‐6‐5 tricyclic heterocycles with various functional groups were synthesized in excellent enantio‐ and diastereoselectivities (>99 % ee, >20:1 d.r.). Furthermore, the deuterium‐labeling experiments and high‐resolution mass spectroscopy demonstrated that a vinylidene ortho‐quinone methide intermediate was involved and possibly resulted from a prototropic rearrangement of 2‐ethynylphenol. Remarkably, a catalyst loading as low as 0.1 mol %, and a gram‐scale synthesis were achieved for this transformation.
Triple play: The enantioselective construction of oxygen‐containing 5‐6‐5 tricyclic heterocycles by a thiourea‐catalyzed asymmetric 4+2 cycloaddition of vinylidene ortho‐quinone methides (VQMs) and benzofurans is reported. A series of oxygen‐containing 5‐6‐5 tricyclic heterocycles having various functional groups were synthesized with excellent enantio‐ and diastereoselectivities.
1,2-Azoles are privileged structures in ligand/catalyst design and widely exist in many important natural products and drugs. In this report, two types of axially chiral 1,2-azoles ...(naphthyl-isothiazole S-oxides with a stereogenic sulfur center and atropoisomeric naphthyl pyrazoles) are synthesized via modified vinylidene ortho-quinone methide intermediates. Diverse products are acquired in satisfying yields and good to excellent enantioselectivities. The vinylidene ortho-quinone methide intermediates bearing two hetero atoms at 5-position have been demonstrated as a platform molecule for the atroposelective synthesis of axially chiral 1,2-azoles. This finding not only enrich our knowledge of vinylidene ortho-quinone methide chemistry but also provide the easy preparation method for diverse atropisomeric heterobiaryls that were inaccessible by existing methodologies. The obtained chiral naphthyl-isothiazole S-oxides and naphthyl-pyrazoles have demonstrated their potential application in further synthetic transformations and therapeutic agents.
