Vicinal Diamines Research Articles

Controlling helical chirality of cobalt complexes by chirality transfer from vicinal diamines

Stereoselective cis-trans isomerism of a Co(III)-N2O2 complex has been achieved by coordinating chiral vicinal diamines. The induced metal-centered helical chirality can be exploited for chirality amplification and asymmetric coordination chemistry.

Synthesis of 15N-labeled vicinal diamines through N-activated chiral aziridines: tools for the NMR study of platinum-based anticancer compounds

A new method for the synthesis of 15N-labeled chiral β-diamines from a common precursor, either optically pure amino acids or anti-β-amino alcohols, is reported. The two diastereomeric series of vicinal diamines are produced through the nucleophilic ring opening of activated chiral aziridines. 15N was introduced by means of [15N]-benzylamine, prepared from 15NH4Cl. The final compounds are highly valuable because [1H–15N] NMR is considered a powerful tool for studying the chemical properties of platinum-based complexes.

The First Catalytic, Enantioselective Aza‐Henry Reaction of an Unactivated Cyclic Imine

AbstractThe aza‐Henry reaction is an efficient route to important chiral, vicinal diamines. Reports of the asymmetric version typically use electron‐deficient acyclic imines. We report the first example of a catalytic, asymmetric aza‐Henry reaction on an unfunctionalized cyclic imine that gives access to enantiopure diamine derivatives under experimentally straightforward conditions. The stereocentre is established through the initial nitromethane addition to the imine. The scalemic intermediate may be trapped through acylation, then crystallized.

A microplate fluorescence assay for DAPA aminotransferase by detection of the vicinal diamine 7,8-diaminopelargonic acid

7,8-Diaminopelargonic acid (DAPA) aminotransferase is an enzyme of the biotin biosynthetic pathway that plays an essential role in Mycobacterium tuberculosis virulence. Inhibition of this enzyme is a potential strategy to combat this microorganism, the causative agent of tuberculosis. To identify new inhibitors as potential drugs, a simple enzymatic assay for high-throughput screening (HTS) is needed. Several methods for measuring DAPA aminotransferase activity are already available. However, requirements for their implementation for HTS are tedious. We describe here a microplate fluorescence assay for DAPA aminotransferase that is simple, cheap, and sensitive, allowing linear detection of DAPA in the range of 20nM to 50μM. The principle of the method is the direct detection in the enzymatic reaction mixture of the vicinal diamine DAPA derivatized with ortho-phthalaldehyde (OPA) and 2-mercaptoethanol (2ME). The assay was validated with the known inhibitor desmethyl-KAPA (8-amino-7-oxopelargonic acid) and adapted to microplate for HTS. The structure of the stable fluorescent adduct formed between a vicinal primary diamine and OPA in the presence of 2ME was characterized by mass spectrometry and nuclear magnetic resonance spectroscopy.

Hydrogen Bonding Directed Intermolecular Cope-Type Hydroamination of Alkenes

Intermolecular hydroamination of unactivated alkenes represents a significant synthetic challenge. An efficient Cope-type hydroamination is achieved under mild conditions for reactions of N-alkylhydroxylamines with allylic amines, using hydrogen bonding to achieve increased reactivity and high regioselectivity. This approach provides a number of highly functionalized vicinal diamine motifs as Markovnikov addition products.

A Diversity-Oriented Approach to Spirocyclic and Fused Hydantoins via Olefin Metathesis

An efficient and general method is reported to prepare a diverse series of 5,5-spirocyclic and 1,5-, 4,5-, and 3,4-fused bicyclic imidazolidinone derivatives based on selective alkylation and ring closing metathesis (RCM) by exploiting the four possible points of diversity in the hydantoin ring. Hydantoins containing trienes and tetraenes undergo selective RCM and cross metathesis to afford functionalized spirohydantoins. A tandem metathesis sequence involving ring closing-ring opening-ring closing and cross metathesis (RC-RO-RC-CM) occurred with a hydantoin triene to give a bicyclic hydantoin dimer in high yield. The fused bicylic dimer could participate in cross metathesis to produce a functionalized fused hydantoin derivative. The methodology establishes novel routes to unnatural amino acids, proline homologues, and cyclic vicinal diamines.

Nucleophilic Ring‐Opening of N‐o‐Nosylaziridines with N‐Chloro‐N‐Sodiocarbamate: Facile Preparation of Differentially Protected Vicinal Diamines

Opening up: A mild nucleophilic ring-opening reaction of activated aziridines with N-chloro-N-sodio-tert-butylcarbamate, which gives differentially protected vicinal diamine derivatives, has been developed. The two protecting groups are selectively removable, and the total synthesis of a long-chain fatty acids oxidation inhibitor, emeriamine, was achieved by using the present method. Boc=tert-butyloxycarbonyl; Ns=nitrophenylsulfonyl.

Synthesis, characterization and spectroscopic investigation of pyrazinoporphyrazine network polymer-supported metal (II)-based catalysts

Chloranil through condensation reaction with vicinal diamine such as diaminomaleonitrile produced heterocyclic monomer, p-benzoquinonebis[2,3-b; 2′,3′-b′]pyrazine-5,6-dinitrile. The tetranitrile monomer was cyclo-tetramerised using lithium/pentanol and acetic acid affording the corresponding tetra p-benzoquinone bis[2,3-b; 2′,3′-b′]pyrazinoporphyrazine)]-based network polymer (2H-Pz). The tetranitril monomer was cyclo-tetramerised using metal salt and quinoline affording the corresponding porphyrazinato-metal II-based network polymers (M-Pz), M = Co, Ni or Cu. Elemental analytical results, IR and NMR spectral data of the prepared molecules are consistent with their assigned formulations. Molecular masses and metal contents of the synthesized polymers proved to be of high molecular masses which confirm the efficiency of tetramerization polymerization and complexation reactions. The prepared pyrazinoporphyrazines were used as efficient catalysts for the oxidation of thiophenol and benzylthiol to their disulfides in the presence of air atmosphere. The results of oxidation of thiophenol and benzylthiol show that after 15 min the maximum yield of the corresponding disulfides reached 95%, 91%, respectively.

Exploration of ring size in a series of cyclic vicinal diamines with σ1 receptor affinity

Imidazolidine and 1,4-diazepane analogs of N-(2-benzofuranyl)methyl-N′-(4-alkoxybenzyl)piperazines were prepared to explore the effect of ring contraction and expansion on σ receptor affinity and subtype selectivity within a series of cyclic diamines. In vitro receptor binding assays revealed that all cyclic vicinal diamines possessed affinity and selectivity for σ1 receptors. The imidazolidines possessed nanomolar σ1 affinities (Ki=6.45–53.5nM), and relatively low levels of subtype selectivity (σ2/σ1=58–237). However, the piperazines and diazepanes achieved picomolar σ1 interactions, with Ki ranges of 0.05–10.28 and 0.10–0.194nM, respectively. Moreover, the piperazines and diazepanes showed excellent discrimination over the σ2 receptor, with σ1 selectivities of 143–16140 and 220–11542, respectively.

Click Mechanochemistry: Quantitative Synthesis of “Ready to Use” Chiral Organocatalysts by Efficient Two‐Fold Thiourea Coupling to Vicinal Diamines

Mechanochemical methods of neat grinding and liquid-assisted grinding have been applied to the synthesis of mono- and bis(thiourea)s by using the click coupling of aromatic and aliphatic diamines with aromatic isothiocyanates. The ability to modify the reaction conditions allowed the optimization of each reaction, leading to the quantitative formation of chiral bis(thiourea)s with known uses as organocatalysts or anion sensors. Quantitative reaction yields, combined with the fact that mechanochemical reaction conditions avoid the use of bulk solvents, enabled solution-based purification methods (such as chromatography or recrystallization) to be completely avoided. Importantly, by using selected model reactions, we also show that the described mechanochemical reaction procedures can be readily scaled up to at least the one-gram scale. In that way, mechanochemical synthesis provides a facile method to fully transform valuable enantiomerically pure reagents into useful products that can immediately be applied in their designed purpose. This was demonstrated by using some of the mechanochemically prepared reagents as organocatalysts in a model Morita-Baylis-Hillman reaction and as cyanide ion sensors in organic solvents. The use of electronically and sterically hindered ortho-phenylenediamine revealed that mechanochemical reaction conditions can be readily optimized to form either the 1:1 or the 1:2 click-coupling product, demonstrating that reaction stoichiometry can be more efficiently controlled under these conditions than in solution-based syntheses. In this way, it was shown that excellent stoichiometric control by mechanochemistry, previously established for mechanochemical syntheses of cocrystals and coordination polymers, can also be achieved in the context of covalent-bond formation.

Chemoenzymatic preparation of optically active trans- and cis-cyclohex-4-ene-1,2-diamine and trans-6-aminocyclohex-3-enol derivatives

Lipase from Burkholderia cepacia (PSL-C) effectively catalyzed the kinetic resolution of both racemic trans-N,N-diallylcyclohex-4-ene-1,2-diamine (±)-6 and its precursor trans-6-(diallylamino)cyclohex-3-enol (±)-5. The resulting optically active vicinal diamine and β-amino alcohol were converted into a precursor of oseltamivir and a cis-cyclohex-4-ene-1,2-diamine derivative, respectively.

Tri-n-butylphosphane catalyzed ring opening of aziridines with secondary amines

Abstract Ring opening of aziridine with dialkyl amine took place readily in the presence of catalytic amounts of tri- n -butylphosphane (10 mol%) in the mixture of CH 3 CN/H 2 O (10:1), giving corresponding vicinal diamines in mediate to high yields (58–95%) with good regioselectivitie, while aromatic secondary amine could not react under the same conditions. Tri- n -butylphosphane exhibited different catalytic selectivity to amines from Lewis acid catalysts.

Diastereoselective Reductive Nitro-Mannich Reactions

A range of nitroalkenes 1 and imines 3 derived from alkyl, aryl, and heteroaryl aldehydes underwent a tandem 1,4-hydride addition nitro-Mannich reaction to afford anti-rich β-nitroamines 4. The crude anti-β-nitroamines 4 could be converted to the corresponding anti-β-nitroacetamides 5 (33 examples) to allow purification in good yield from the parent nitroalkenes (60-87%), and with a high diastereomeric ratio (90:10 to mostly >95:5). A representative selection of anti-β-nitroacetamides 5 (five examples) were reduced to vicinal diamines 7 with zinc hydrochloride; concomitant acyl migration provided differentially protected vicinal diamines 7 in good yield (80-91%).

Stereocontrolled Synthesis of Vicinal Diamines by Organocatalytic Asymmetric Mannich Reaction of N-Protected Aminoacetaldehydes: Formal Synthesis of (−)-Agelastatin A

The 1,2-diamine (vicinal diamine) motif is present in a number of natural products with interesting biological activity and in many chiral molecular catalysts. The efficient and stereocontrolled synthesis of enantioenriched vicinal diamines is still a challenge to modern chemical methodology. We report here both syn- and anti-selective asymmetric direct Mannich reactions of N-protected aminoacetaldehydes with N-Boc-protected imines catalyzed by proline and the axially chiral amino sulfonamide (S)-3. This organocatalytic process represents the first example of a Mannich reaction using Z- or Boc-protected aminoacetaldehyde as a new entry of α-nitrogen functionalized aldehyde nucleophile in enamine catalysis. The obtained optically active vicinal diamines are useful chiral synthons as exemplified by the formal synthesis of (-)-agelastatin A.

ChemInform Abstract: A Catalytic Tethering Strategy: Simple Aldehydes Catalyze Intermolecular Alkene Hydroaminations.

Herein we describe a catalytic tethering strategy in which simple aldehyde precatalysts enable, through temporary intramolecularity, room-temperature intermolecular hydroamination reactivity and the synthesis of vicinal diamines. The catalyst allows the formation of a mixed aminal from an allylic amine and a hydroxylamine, resulting in a facile intramolecular hydroamination event. The promising enantioselectivities obtained with a chiral aldehyde also highlight the potential of this catalytic tethering approach in asymmetric catalysis and demonstrate that efficient enantioinduction relying only on temporary intramolecularity is possible.

Copper-Catalyzed Aerobic [3+2]-Annulation of N-Alkenyl Amidines

A method for the synthesis of bi- and tricyclic amidines has been developed through copper-catalyzed aerobic [3+2]-annulation reaction of N-alkenyl amidines. These cyclic amidines could be converted into mono-benzyl-protected vicinal diamines by the reduction with aluminum hydride.

ChemInform Abstract: Iron‐Catalyzed Ring‐Opening of meso‐Aziridines with Amines.

AbstractN‐Arylaziridines are efficient substrates for the formation of vicinal diamines, generally within a short time and including labile structures such as (VIIIc).

Chiral picolylamines for Michael and aldol reactions: probing substrate boundaries

Here we report on inroads concerning increased substrate breadth via the picolylamine organocatalyst template, a vicinal chiral diamine based on a pyridine-primary amine motif. The addition of cyclohexanone to β-nitrostyrene has many catalyst solutions, but cyclopentanone and isobutyraldehyde additions continue to be challenging. PicAm-3 (10 mol%) readily allows the Michael addition of cyclopentanone or isobutyraldehyde (5.0 equiv.) to β-nitrostyrene derivatives. By contrast, PicAm-1 (7.0 mol%) is optimal for catalyzing the aldol reaction of cyclohexanone or cycloheptanone (3.3 equiv.) with aromatic aldehydes. Eighteen products are reported and for each reaction type new products are reported (4b-d, 9c). Very good yields and stereoselectivities are generally noted. The reactions, which require an acid additive, proceed via a transient chiral enamine and a mechanistic case is put forth for a bifunctional catalysis model.

Chemo- and enantioselective Rh-catalysed hydrogenation of 3-methylene-1,2-diazetidines: application to vicinal diamine synthesis

Rhodium catalysed hydrogenation of 3-methylene-1,2-diazetidines with a range of chiral ligands is reported. Using Mandyphos, excellent levels of chemo- and enantioselectivity (up to 89% ee) can be achieved. Reductive cleavage of the derived 3-substituted 1,2-diazetidine with LiDBB provides the enantioenriched biscarbamate protected 1,2-diamine.

A Catalytic Tethering Strategy: Simple Aldehydes Catalyze Intermolecular Alkene Hydroaminations

Herein we describe a catalytic tethering strategy in which simple aldehyde precatalysts enable, through temporary intramolecularity, room-temperature intermolecular hydroamination reactivity and the synthesis of vicinal diamines. The catalyst allows the formation of a mixed aminal from an allylic amine and a hydroxylamine, resulting in a facile intramolecular hydroamination event. The promising enantioselectivities obtained with a chiral aldehyde also highlight the potential of this catalytic tethering approach in asymmetric catalysis and demonstrate that efficient enantioinduction relying only on temporary intramolecularity is possible.