An Asymmetric Organocatalysis Approach to the Prenylated Alkaloid Family

Michael addition of a proline-derived triketopiperazine (TKP) to β-substituted enones and acrylamides, mediated by a cinchona alkaloid catalyst, delivers products possessing a bicyclo­[2.2.2]­diazaoctane structure in high yield and enantiomeric ratio (er). Further modification of the amide products toward polycyclic scaffolds resembling members of the prenylated alkaloid family is also demonstrated

Supramolecular Behavior of Adenine with Succinic, Fumaric, and Maleic Acids: Tautomerism, Cocrystallization, Salt Formation, and Solvation

The powerful hydrogen bonding capability of adenine makes it a key component of the DNA double helix, while as a crystalline molecular material, these hydrogen bond donors and acceptors make it a good potential cocrystal component possessing distinct physical properties. Here, we report the preparation and structure determination of four adenine-based multicomponent adducts formed with a number of dicarboxylic acids: an anhydrous cocrystal with succinic acid (<b>1</b>), anhydrous salts with fumaric acid (<b>2</b>) and maleic acid (<b>3</b>), and a methanolated salt with maleic acid (<b>4</b>). The supramolecular behavior of adenine in these materials is discussed in terms of strong hydrogen-bonded bidentate motifs formed between the adenine and acid components and the homomeric adenine synthons retained in these structures. The additional formation of a CH···N interaction on the Watson–Crick site in (<b>3</b>) enables the stabilization of the unusual 3<i>H</i>,7<i>H</i> adeninium tautomer within a purely molecular material

Supramolecular Behavior of Adenine with Succinic, Fumaric, and Maleic Acids: Tautomerism, Cocrystallization, Salt Formation, and Solvation

The powerful hydrogen bonding capability of adenine makes it a key component of the DNA double helix, while as a crystalline molecular material, these hydrogen bond donors and acceptors make it a good potential cocrystal component possessing distinct physical properties. Here, we report the preparation and structure determination of four adenine-based multicomponent adducts formed with a number of dicarboxylic acids: an anhydrous cocrystal with succinic acid (<b>1</b>), anhydrous salts with fumaric acid (<b>2</b>) and maleic acid (<b>3</b>), and a methanolated salt with maleic acid (<b>4</b>). The supramolecular behavior of adenine in these materials is discussed in terms of strong hydrogen-bonded bidentate motifs formed between the adenine and acid components and the homomeric adenine synthons retained in these structures. The additional formation of a CH···N interaction on the Watson–Crick site in (<b>3</b>) enables the stabilization of the unusual 3<i>H</i>,7<i>H</i> adeninium tautomer within a purely molecular material

Supramolecular Behavior of Adenine with Succinic, Fumaric, and Maleic Acids: Tautomerism, Cocrystallization, Salt Formation, and Solvation

The powerful hydrogen bonding capability of adenine makes it a key component of the DNA double helix, while as a crystalline molecular material, these hydrogen bond donors and acceptors make it a good potential cocrystal component possessing distinct physical properties. Here, we report the preparation and structure determination of four adenine-based multicomponent adducts formed with a number of dicarboxylic acids: an anhydrous cocrystal with succinic acid (<b>1</b>), anhydrous salts with fumaric acid (<b>2</b>) and maleic acid (<b>3</b>), and a methanolated salt with maleic acid (<b>4</b>). The supramolecular behavior of adenine in these materials is discussed in terms of strong hydrogen-bonded bidentate motifs formed between the adenine and acid components and the homomeric adenine synthons retained in these structures. The additional formation of a CH···N interaction on the Watson–Crick site in (<b>3</b>) enables the stabilization of the unusual 3<i>H</i>,7<i>H</i> adeninium tautomer within a purely molecular material

Supramolecular Behavior of Adenine with Succinic, Fumaric, and Maleic Acids: Tautomerism, Cocrystallization, Salt Formation, and Solvation

The powerful hydrogen bonding capability of adenine makes it a key component of the DNA double helix, while as a crystalline molecular material, these hydrogen bond donors and acceptors make it a good potential cocrystal component possessing distinct physical properties. Here, we report the preparation and structure determination of four adenine-based multicomponent adducts formed with a number of dicarboxylic acids: an anhydrous cocrystal with succinic acid (<b>1</b>), anhydrous salts with fumaric acid (<b>2</b>) and maleic acid (<b>3</b>), and a methanolated salt with maleic acid (<b>4</b>). The supramolecular behavior of adenine in these materials is discussed in terms of strong hydrogen-bonded bidentate motifs formed between the adenine and acid components and the homomeric adenine synthons retained in these structures. The additional formation of a CH···N interaction on the Watson–Crick site in (<b>3</b>) enables the stabilization of the unusual 3<i>H</i>,7<i>H</i> adeninium tautomer within a purely molecular material

Rigid and concave, 2,4-cis-substituted azetidine derivatives: A platform for asymmetric catalysis

A series of single enantiomer, 2,4-<i>cis</i>-disubstituted amino azetidines were synthesised and used as ligands for copper-catalysed Henry reactions of aldehydes with nitromethane. Optimisation of ligand substituents and the reaction conditions was conducted. The enantiomeric excess of the formed products was highest when alkyl aldehydes were employed in the reaction (>99% e.e.). The absolute stereochemistry of one representative azetidine derivative salt was determined by analysis of the Flack parameter of an XRD single crystal structure. The origin of selectivity in catalysis was investigated computationally, revealing the importance of the amino-substituent in determining the stereochemical outcome. A racemic platinum complex of a <i>cis</i>-disubstituted azetidine is examined by XRD single crystal structure analysis with reference to its steric parameters, and analogies to the computationally determined copper complex catalyst are drawn.<br

Palladium and platinum 2,4-cis-amino azetidine and related complexes

Crystal structures and structural interpretation of complexes of azetidine (and related) ligands coordinated to palladium(II) and platinum(II)

Data_Sheet_2_Palladium and Platinum 2,4-cis-amino Azetidine and Related Complexes.ZIP

<p>Seven N,N'-palladium(II) chloride complexes, one N,N'-palladium(II) acetate complex of 2,4-cis-azetidines where prepared and analyzed by single crystal XRD. Two platinum(II) chloride N,N'-complexes of 2,4-cis-azetidines where prepared and analyzed by single crystal XRD. Computational analysis and determination of the %Vbur was examined conducted. A CNN' metallocyclic complex was prepared by oxidative addition of palladium(0) to an ortho bromo 2,4-cis-disubstituted azetidine and its crystal structure displays a slightly pyramidalized metal-ligand orientation.</p

Data_Sheet_3_Palladium and Platinum 2,4-cis-amino Azetidine and Related Complexes.ZIP

<p>Seven N,N'-palladium(II) chloride complexes, one N,N'-palladium(II) acetate complex of 2,4-cis-azetidines where prepared and analyzed by single crystal XRD. Two platinum(II) chloride N,N'-complexes of 2,4-cis-azetidines where prepared and analyzed by single crystal XRD. Computational analysis and determination of the %Vbur was examined conducted. A CNN' metallocyclic complex was prepared by oxidative addition of palladium(0) to an ortho bromo 2,4-cis-disubstituted azetidine and its crystal structure displays a slightly pyramidalized metal-ligand orientation.</p

Semipinacol Rearrangement of <i>Cis</i>-Fused β-Lactam Diols into Keto-Bridged Bicyclic Lactams

The 6-azabicyclo[3.2.1]octane ring system, prevalent in a range of biologically active molecules, is prepared through a novel semipinacol rearrangement utilizing a cyclic phosphorane or sulfite intermediate. The rearrangement proceeds with exclusive <i>N</i>-acyl group migration of a β-lactam ring and results in carbonyl functionality at the 7- and bridging 8-position of the bicycle. Precursor ring-fused β-lactam diols are prepared through a sequence of 4-<i>exo trig</i> carbamoyl radical cyclization, regioselective dithiocarbamate group elimination, and dihydroxylation