Synthesis of Bis(indolyl)methanes through an Alkylation Reaction of Indoles with Sodium Alkoxides

Herein we wish to describe an alkylation reaction of indoles with sodium alkoxides for the synthesis of bis(indolyl)methanes. 1-Tetralone was proved to be an efficient hydrogen acceptor thus avoiding the use of precious transition metals such as Ru and Ir. This reaction features transition metal-free conditions, readily available starting materials, and gram-scale synthesis.

Crystal structure of bis(1,8-dibenzoyl-7-methoxynaphthalen-2-yl)terephthalate: Terephthalate phenylene moiety acts as bidentate hydrogen acceptor of bidirectional C-H···π non-classical hydrogen bonds

The title compound lies about a crystallographic inversion centre located at the terephthalate moiety. The two peri-benzoylnaphthalene units having atrope chirality are also situated centrosymmetrically. In the two peri-benzoylnaphthalene moieties, two benzoyl groups are substituted at 1 and 8 carbons of the naphthalene ring in anti-orientation. Then two absolute configurations of peri-benzoylnaphthalene moieties are consequently assigned as complementary to each other, i.e., one unit has R,R-configuration and the other S,S-one, respectively. The two benzoyl groups in peri-benzoylnaphthalene moiety and the terephthalate phenylene ring are non-coplanarly located against the naphthalene ring. The dihedral angles of each benzene ring of two benzoyl groups and terephthalate unit with the naphthalene ring are 73.73 and 75.96, and 71.79°. In molecular packing, several kinds of weak interactions are responsible to induce three-dimensional molecular network. Especially, the synergetic effect realized through the bidentate hydrogen acceptor function in bidirectional C-H···π non-classical hydrogen bonds by the terephthalate phenylene ring moiety plausibly plays the determining role.

Ultimate Molecular Theory of Sweet Taste

More than thirty years ago, I proposed a theory about sweet and bitter molecules’ recognition by protein helical structures. Unfortunately the papers could not go to public platform until now. The sweet and bitter taste theory is updated and presented in separated papers1,2. The sweet taste theory conveys that sweet molecules are recognized by receptor protein helical structures and the recognition process is a dynamic action, in which the sweet receptor protein helix has a torsion-spring-like oscillation between helical structures of 3.6 and 3 amino acids per turn. To help this kind of oscillation, there are two kinds of hydrogen donor and hydrogen acceptor DH-B entities for both receptor and sweet molecules: H-bond or non-H-bond. The distances between DH and B could be up to ~ 8.5 Å. The receptor H-bond type DH-B entities are the NH-O pairs forming H-bonds in protein helices; the receptor non-H-bond type DH-B entities are the ones from two pairs of NH-Os forming H-bonds which are about one turn away. To facilitate this kind of movement, the interaction of DH-Bs of a sweet molecule with those of sweet receptor, through a pair of complementary hydrogen bonds, must have hydrogen bond complementarities, which means Hbond type of ligands’ DH-Bs reacts on non-H-bond type of receptor’s O-NHs, and vice versa. As the oscillation may have different extent, it translates to sweet intensity. As recognition sites are only associated with a small fraction – helix structure of whole sweet receptor, multiple binding sites or multiple receptors are well expected.

Deciphering Aspartyl Peptide Sweeteners Using the Ultimate Molecular Theory of Sweet Taste

More than thirty years ago, I proposed a theory about sweet and bitter molecules’ recognition by protein helical structures. Unfortunately the papers<br>could not go to public platform until now. The sweet and bitter taste theory is updated and presented in separated papers. 1,2 Under the guidance of the sweet<br>receptor helix recognition theory 1, aspartyl/aminomalonyl peptide sweeteners are deciphered. Here it demonstrates that, this series of sweeteners has a<br>hydrogen-bond type hydrogen donor - hydrogen acceptor DH-B moiety and their DH-B is very special. Their B of the DH-B moiety is an oxygen of the carboxylic<br>group, which is widely accepted one. The DH of the DH-B moiety however is the NH of the aspartyl/aminomalonyl peptide, which is a selection for the first time to<br>the best of my knowledge. Even more unusual, their dynamic action acts through<br>the hydrogen on alpha carbon of aspartyl/aminomalonyl group. The receptor main and side grooves have different space characteristics in accepting sweet<br>molecules’ groups, which is elaborated in this paper. This unprecedented elucidation well explains the aspartyl/aminomalonyl peptide sweeteners’<br>phenomenon and, in return, strongly supports this sweet receptor helix recognition theory.

Deciphering Aspartyl Peptide Sweeteners Using the Ultimate Molecular Theory of Sweet Taste

More than thirty years ago, I proposed a theory about sweet and bitter molecules’ recognition by protein helical structures. Unfortunately the papers<br>could not go to public platform until now. The sweet and bitter taste theory is updated and presented in separated papers. 1,2 Under the guidance of the sweet<br>receptor helix recognition theory 1, aspartyl/aminomalonyl peptide sweeteners are deciphered. Here it demonstrates that, this series of sweeteners has a<br>hydrogen-bond type hydrogen donor - hydrogen acceptor DH-B moiety and their DH-B is very special. Their B of the DH-B moiety is an oxygen of the carboxylic<br>group, which is widely accepted one. The DH of the DH-B moiety however is the NH of the aspartyl/aminomalonyl peptide, which is a selection for the first time to<br>the best of my knowledge. Even more unusual, their dynamic action acts through<br>the hydrogen on alpha carbon of aspartyl/aminomalonyl group. The receptor main and side grooves have different space characteristics in accepting sweet<br>molecules’ groups, which is elaborated in this paper. This unprecedented elucidation well explains the aspartyl/aminomalonyl peptide sweeteners’<br>phenomenon and, in return, strongly supports this sweet receptor helix recognition theory.

Ultimate Molecular Theory of Sweet Taste

More than thirty years ago, I proposed a theory about sweet and bittermolecules’ recognition by protein helical structures. Unfortunately the paperscould not go to public platform until now. The sweet and bitter taste theory isupdated and presented in separated papers1,2. The sweet taste theory conveysthat sweet molecules are recognized by receptor protein helical structures andthe recognition process is a dynamic action, in which the sweet receptor proteinhelix has a torsion-spring-like oscillation between helical structures of 3.6 and 3amino acids per turn. To help this kind of oscillation, there are two kinds ofhydrogen donor and hydrogen acceptor DH-B entities for both receptor andsweet molecules: H-bond or non-H-bond. The distances between DH and Bcould be up to ~ 8.5 Å. The receptor H-bond type DH-B entities are the NH-Opairs forming H-bonds in protein helices; the receptor non-H-bond type DH-Bentities are the ones from two pairs of NH-Os forming H-bonds which are aboutone turn away. To facilitate this kind of movement, the interaction of DH-Bs of asweet molecule with those of sweet receptor, through a pair of complementaryhydrogen bonds, must have hydrogen bond complementarities, which means Hbondtype of ligands’ DH-Bs reacts on non-H-bond type of receptor’s O-NHs, andvice versa. As the oscillation may have different extent, it translates to sweetintensity. As recognition sites are only associated with a small fraction – helixstructure of whole sweet receptor, multiple binding sites or multiple receptors arewell expected.

Exothermic methane coupling with ethylene as a hydrogen acceptor toward two-step methane conversion to ethylene

Exothermic methane coupling with ethylene as a hydrogen acceptor was proposed, which allows splitting of direct methane coupling forming ethylene into a two-step reaction (it permits reaction splitting) involving ethane cracking, a common industrial process.

Synthesis and Photophysical Characterization of 2′-Aminochalcones

Chalcones present biological activity and are, therefore, currently studied for their therapeutic potential. They have shown antitumor, anti-inflammatory, antifungal and antibacterial properties. These compounds occur in nature as secondary metabolites of plants and are precursors of flavonoid biosynthesis. Generally, they are not luminescent, but derivatives with some particular patterns of substitution can present fair quantum yields. Excited State Intramolecular Proton Transfer (ESIPT) is a particular case of tautomerization, and some molecules can exhibit ESIPT fluorescence if their structures incorporate an intramolecular hydrogen bonding interaction between a hydrogen donor (-OH or -NH) and a hydrogen acceptor. If the dye is fluorescent, emission from both tautomers may be observed, leading to a dual emission. The chalcones with a strong push–pull character, compounds 2c, 3c and 4c, presented dual emission of keto–enol tautomerism as a consequence of ESIPT.