Tertiary Diamines Research Articles

Bio-inspired Chiral Primary Amine Catalysis

The search for new catalysts with superior performance and broad applicability remains a central theme in asymmetric organocatalysis. Inspired by Nature as well as by numerous previous efforts, we have developed chiral primary–tertiary diamines as both functional and mechanistic enzyme mimics, showing unprecedented scope in enamine-aldol reactions and significant potential in the reactions of acroleins. Our endeavors focusing on this type of catalysts are summarized in this account. 1 Introduction 2 General Features of Primary–Tertiary Vicinal Diamine/TfOH; Multifunctional Catalysis 3 Asymmetric Supramolecular Primary Amine Catalysis; Roles of the Hydrophobic Cavity 4 Asymmetric Direct Aldol Reaction of Aliphatic Ketones 5 Asymmetric Direct Cross-Aldol Reaction of Aldehydes 6 Asymmetric Retro-Aldol and Transfer-Aldol Reactions 7 Iminium Catalysis with Chiral Primary–Tertiary Diamines 8 Bifunctional Catalysis of Primary–Tertiary Diamines in the Baylis–Hillman Reaction 9 Conclusion, Remarks, and Outlook

ChemInform Abstract: Highly Enantioselective Aldol Reactions Using a tropos Dibenz[c,e]azepine Organocatalyst.

AbstractA newly synthesized chiral primary tertiary diamine salt possessing a dibenz[c,e]azepine ring, promotes highly enantioselective crossed‐aldol reactions between cyclohexanone (I) and a series of aromatic aldehydes.

Highly efficient direct large-scale stoichiometric aldol reactions catalyzed by a new diamine salt in the presence of water

A new type of primary–tertiary diamine salt prepared can be used as a catalyst for direct aldol reaction and can display high yields, diastereoselectivities (up to 99 : 1), and enantiomeric excesses (up to 98%), by using stoichiometric amounts of cyclic ketones and various aryl aldehydes in the presence of water. This new catalyst can also be efficiently applied in large-scale reactions with the enantioselectivity being maintained at the same level, which indicates the potential for applications in industry.

ChemInform Abstract: Highly Enantioselective Aldol Reaction of Acetone with β,γ‐Unsaturated α‐Keto Esters Promoted by Simple Chiral Primary—Tertiary Diamine Catalysts.

AbstractUnder optimized conditions, acetone as well as cyclic ketones give the corresponding chiral tertiary α‐hydroxycarboxylic esters with up to 96% e.e.

Highly enantioselective aldol reactions using a tropos dibenz[ c, e]azepine organocatalyst

The four-step synthesis of a chiral primary tertiary diamine salt, possessing a tropos dibenz[ c, e]azepine ring is described. It is shown that 3.5–5 mol % of this salt is capable of promoting highly enantioselective crossed-aldol reactions between cyclohexanone and a series of aromatic aldehydes. In all cases, the aldol reactions proceed with high diastereoselectivity for the anti-aldol product. The outcome of crossed-aldol reactions involving other cyclic ketones and acyclic ketones are also described. All examples involving cyclic ketones result in selectivity for the anti-aldol products, whereas acyclic ketones were found to favour the syn-aldol products. A discussion on the role of the chiral primary tertiary diamine salt in the catalysis of the aldol reactions is also presented.

Vibrations of a chelated proton in a protonated tertiary diamine

Vibrational spectra of the conjugate acid of Me(2)NCH(2)CH(2)CH(2)CH(2)NMe(2) (N,N,N',N'-tetramethylputrescine) have been examined in the gaseous and crystalline phases using Infrared Multiple Photon Dissociation (IRMPD) spectroscopy, Inelastic Neutron Scattering (INS), and high pressure Raman spectroscopy. A band observed near 530 cm(-1) is assigned to the asymmetric stretch of the bridging proton between the two nitrogens, based on deuterium substitution and pressure dependence. The NN distance measured by X-ray crystallography gives a good match to DFT calculations, and the experimental band position agrees with the value predicted from theory using a 2-dimensional potential energy surface. The reduced dimensionality potential energy surface, which treats the ion as though it possesses a linear NHN geometry, shows low barriers to proton transit from one nitrogen to the other, with zero point levels close to the barrier tops. In contrast, two other related systems containing strong hydrogen bonds do not exhibit the same spectroscopic signature of a low barrier hydrogen bond (LBHB). On the one hand, the IRMPD spectra of the conjugate acid ions of the amino acid N,N,N',N'-tetramethylornithine (in which the two nitrogens have different basicities) show fewer bands and no comparable isotopic shifts in the low frequency domain. On the other hand, the IRMPD spectrum of the shorter homologue Me(2)NCH(2)CH(2)CH(2)NMe(2) (N,N,N',N'-tetramethyl-1,3-propanediamine), for which the NHN bond angle deviates substantially from linearity, displays more than one band in the 1100-1400 cm(-1) domain, which vanish as a consequence of deuteration.

Highly enantioselective aldol reaction of acetone with β,γ-unsaturated α-keto esters promoted by simple chiral primary–tertiary diamine catalysts

A series of primary-tertiary diamine catalysts were successfully applied to promote the enantioselective aldol reaction of acetone with β,γ-unsaturated α-keto esters in excellent yields (up to 99%) and enantioselectivities (up to 96% ee).

ChemInform Abstract: Chiral Primary—Tertiary Diamine—Broensted Acid Salt Catalyzed Syn‐Selective Cross‐Aldol Reaction of Aldehydes.

AbstractThe salt generated from the diamine shown in the scheme and TfOH efficiently promotes the asymmetric, syn‐selective cross‐aldol reaction of electron‐poor aromatic aldehydes with propionaldehyde and the protected glycol aldehyde (VI).

ChemInform Abstract: Direct Asymmetric Aldol Reaction of Acetone with α‐Ketoesters Catalyzed by Primary—Tertiary Diamine Organocatalysts.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Direct asymmetric aldol reaction of acetone with α-ketoesters catalyzed by primary–tertiary diamine organocatalysts

Novel primary–tertiary diamine organocatalysts derived from l-serine were utilized to promote enantioselective aldol reaction of acetone with α-ketoesters. The desired products were obtained in high yields and with good to excellent enantioselectivities (up to 95% ee).

Ethylene Polymerization Initiated by Tertiary Diamine/n-Butyllithium Complexes: An Interpretation from Density Functional Theory Study

The mechanism of ethylene insertions into eight tertiary diamine/n-butyllithium complexes has been studied at the BLYP/DNP level. In contrast to the cationic coordination polymerization in which a strong coordination complex between ethylene and the metal center is formed prior to ethylene insertion, there is only a weak van der Waals complex between ethylene and tertiary diamine/n-butyllithium complex. After crossing a four-membered-ring transition state, ethylene inserts into the Li-C bond. The insertion barriers for the eight reactions are in the range of 6.9-11.0 kcal/mol, comparable to those of ethylene cationic coordination polymerizations. However, the polymerization activities of ethylene anionic polymerizations are much lower than those of cationic coordination polymerizations. Comparing the energy profiles of these ethylene anionic polymerizations with those of cationic coordination polymerizations, it can be found that the transition states in the ethylene anionic polymerizations are higher in energy than the reactants, while the transition states in ethylene cationic coordination polymerizations are lower than the reactants. Therefore, ethylene anionic polymerizations need additional energy to climb the energy barriers, while the energies for overcoming the transition states in the cationic coordination polymerizations can be obtained from reactants that are higher in energy than the reactants. We reason the differences in their energy profiles could be one of the reasons for the lower activity of ethylene anionic polymerization than ethylene cationic coordination polymerization despite their comparable insertion barriers.

Syntheses, crystal structure and chromotropic properties of dinuclear copper(II) complexes of tertiary diamine with hydroxo bridge

Dinuclear copper(II) complex with the general formula [(diamine)Cu(OH)] 2(ClO 4) 2, where diamine stands for N, N-dialkyl, N′-benzyl-ethylenediamine, were prepared. The complexes were characterized by elemental analysis, spectroscopic, conductance measurements, and X-ray structural analysis. The complexes are soluble in various organic solvents and show positive solvatochromism. Thermochromism was also observed particularly in strong donor solvents.

An efficient chemoenzymatic method to prepare optically active primary–tertiary trans-cycloalkane-1,2-diamines

Optically active trans- N-Boc-cyclopentane- and cyclohexane-1,2-diamines ( 7) were prepared by a chemoenzymatic method from the corresponding (±)- trans- N, N-diallylcycloalkane-1,2-diamine. These mono-carbamates 7 (ee=99%) were used as the starting materials in the syntheses of different vicinal primary–tertiary diamines. Thus, by means of a simple three-step sequence involving a reductive-amination of an aromatic aldehyde with 7, N-methylation and finally, cleavage of the Boc group, several trans- N-(arylmethyl)- N-methylcyclopentane- and cyclohexane-1,2-diamines were obtained in high yields.

ChemInform Abstract: Chiral Primary—Tertiary Diamine Catalysts Derived From Natural Amino Acids for syn‐Aldol Reactions of Hydroxy Ketones.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synergistic effect of the mixtures of heavy metal chelates with tertiary aromatic diamines in the inhibition of ethylbenzene oxidation

The synergistic effect due to the interaction between the components in mixtures of heavy metal chelates with tertiary aromatic diamines was revealed in the model reaction of initiated ethylbenzene oxidation. It was shown that the magnitude of the synergistic effect calculated from the initial rates of oxidation and the duration of the inhibitory action of the mixtures depended on the electron-donating properties of tertiary amines and increased with a decrease in the half-wave potential of electrochemical oxidation of tertiary amines. The parameter characterizing the antiradical activity was determined for two amines.

Chelation of a Proton by an Aliphatic Tertiary Diamine

A series of monoprotonated aliphatic diamines has been examined, which crystallize in three general motifs: salt-bridged, cyclic, or clustered. The monoprotonated triflic acid salt of Me2N(CH2)4NMe2 forms a proton-bridged cyclic cation. The internal N-N distance is 2.66 A, with the bridging proton in the middle, having an NHN angle >/=172 degrees. The triflate oxygens lie more than 4 A away from the midpoint between the nitrogen atoms, indicating that a salt bridge does not form. The average NH distance in a solid sample was determined by measuring the 15N-H dipolar coupling in the triflic acid salt of the completely deuterated diamine (CD3)2N(CD2)4N(CD3)2. The value of the dipolar coupling constant, 5250 +/- 90 Hz, corresponds to an average NH distance of 1.32 A, nearly half-the NN distance. That result agrees with DFT calculations, which give a double-well potential minimum for proton transit between the two amino groups, having a zero-point vibrational level close to the barrier top. Theory predicts that the maximum value of the zero point vibrational wave function is almost coincident with a local potential energy maximum, consistent with the experimental findings.

ChemInform Abstract: Synthesis and Application of a New Pseudo C2‐Symmetric Tertiary Diamine for the Enantioselective Addition of MeLi to Aromatic Imines.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Chiral Tertiary Diamines in Asymmetric Synthesis

Chiral Tertiary Diamines in Asymmetric Synthesis

Synthesis and application of a new pseudo C2-symmetric tertiary diamine for the enantioselective addition of MeLi to aromatic imines

A new tertiary pseudo C 2-symmetric diamine derived from (1 S,2 S)-(+)-pseudoephedrine was synthesized and tested in the enantioselective addition of methyllithium on different aromatic imines. A comparative study with a similar C 2-symmetric ligand derived from the cyclohexane diamine showed better reactivity and enantioselectivity up to 91%.

A Simple Primary—Tertiary Diamine—Broensted Acid Catalyst for Asymmetric Direct Aldol Reactions of Linear Aliphatic Ketones.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.