Asymmetric synthesis of enantio-enriched acyclic α-amino alkylstannanes and rearrangement behavior of carbanions thereof

An efficient stereocontrolled synthesis of enantio-enriched N-Boc-N-allyl-α-amino alkylstannanes and N,N-diallylic α-amino alkylstannanes starting from enantio-enriched α-hydroxy alkylstannane has been developed. The aza-Wittig rearrangement of enantio-defined N,N-diallyl-α-amino alkyllithium, generated by tin-lithium exchange, is shown to proceed predominantly with inversion of configuration at the Li-bearing carbon terminus.     

Ugi amine-derived P,N- and P,P-ligands with N-alkyltriethoxysilyl tethers: synthesis and evaluation of mesoporous silica-supported Pd complexes in asymmetric allylic substitution reactions

A facile approach to the synthesis of several types of chiral P,N- and P,P-ligands bearing triethoxysilyl groups starting from N,N-diemthyl-1-ferrocenylethylamine (Ugi amine) has been developed. Allyl palladium complexes of these ligands have been prepared, characterized, and grafted on mesoporous silica. The resulting silica-supported complexes have been shown to catalyze asymmetric allylic alkylation and aminations reactions with moderate enantioselectivities.     

Versatile synthesis of oxindole-1,3-dicarboxamides

A new, high-yielding synthesis of oxindole-1,3-dicarboxamides was elaborated starting from 1-phenoxycarbonyl-3-ethoxycarbonyl-2-oxindole and 1,3-diphenoxycarbonyl-2-oxindole. This method permits also the preparation of N,N,N′-tri- and N,N,N′,N′-tetrasubstituted oxidole-1,3-dicarboxamides, families of compounds that are unknown in the literature. The scope and limitations of the methodology have also been investigated, and a remarkable selectivity has been observed among the amines used in the amidation steps.     

N-(3-Trimethylsilyl)propargyl amino esters via reductive amination

N-Propargyl amino esters are useful starting materials in a variety of settings. General reductive amination conditions for N-(3-trimethylsily)propargylation of amino esters have been developed. These conditions demonstrated greater tolerance for nucleophilic side chains (amines and alcohols) than has been previously reported. This procedure produced a variety of N-(3-trimethylsilyl)propargyl amino esters in good to excellent yield.     

Iodine(III)-mediated aromatic amidation vs olefin amidohydroxylation. The amide N-substituent makes the difference

A series of N-methoxy- and N-para-methoxyphenylacetamides simultaneously substituted at the α position by a benzyl and an allyl group have been treated with phenyliodine(III)bis(trifluoroacetate) to generate stabilized N-acylnitrenium intermediates. It has been observed that, when starting from N-methoxy substituted amides, such intermediates are intramolecularly trapped by nucleophilic arene rings to render the quinolinone skeleton. Alternatively, under the same reaction conditions, N-para-methoxyphenylamides afford pyrrolidinone derivatives through an olefin amidohydroxylation process.     

NH4I-promoted N-acylation of amines via the transamidation of DMF and DMA under metal-free conditions

An unprecedented NH₄I-promoted N-formylation and N-acetylization of various amines with dimethylformamide (DMF) and dimethylacetamide (DMA) has been developed. This protocol shows broad substrate scope for aromatic, aliphatic, and heterocyclic amines, which provides a metal-free strategy for N-acylation featuring mild reaction conditions, as well as inexpensive and readily available starting materials.     

An efficient and scalable synthesis of N-(benzyloxycarbonyl)- and N-(methyloxycarbonyl)-(S)-vinylglycinol

An efficient and scalable synthesis of N-(benzyloxycarbonyl)- and N-(methyloxycarbonyl)-(S)-vinylglycinol has been reported starting from the commercially available (l)-methionine. The scale-up preparation consisted of 5 steps and delivered up to 50 g of the desired N-protected β-amino alcohols in 32% and 36% overall yields.     

A convenient synthesis of methyl N-acetyl-α-d-lividosaminide from d-glucal

Methyl N-acetyl-α-d-lividosaminide has been synthesised starting from 4,6-di-O-benzyl-d-glucal via a new nitro glucal derivative in six steps.     

Palladium-catalyzed carbonylative synthesis of N-cyanobenzamides from aryl iodides/bromides and cyanamide

A novel and convenient protocol for the synthesis of N-cyanobenzamides starting from readily available aryl halides and cyanamide via palladium-catalyzed aminocarbonylation has been developed. The protocol utilizes Mo(CO)₆ as the CO source or CO(gas) and affords the desired N-cyanobenzamides in moderate to good yields.     

N-alkylation of nitriles(1)—II. Synthesis polymerization and quaternization of N-substituted acrylamidines. A new class of acrylic monomers16)

N-Substituted acrylamidines, a new class of acrylic monomers, have been prepared from acrylonitrile, an alkyl halide, a Lewis acid and an amine. The synthesis involves the aminolysis of an N-alkylacrylonitrilium salt with an aliphatic or an aromatic amine. Following this general scheme, 4 examples of N-substituted acrylamidines have been already obtained in 30–50 per cent overall yield based on the starting nitrile. Two of them have been polymerized with azobisisobutyronitrile as initiator. By the action of dimethylsulphate, a polyacrylamidinium salt (a new type of polyelectrolyte) has been prepared.     

Synthesis of the four enantiomers of diethyl 1,2-di(N-Boc-amino)propylphosphonates

A simple and efficient synthetic strategy to all four enantiomerically pure diethyl 1,2-di(N-Boc-amino)propylphosphonates has been elaborated starting from the corresponding N-[(R)-(1-phenylethyl)]aziridine-(2S)- and N-[(S)-(1-phenylethyl)]aziridine-(2R)-carboxaldehydes, employing a one-pot three-components Kabachnik-Fields reaction followed by the hydrogenolytic removal of the chiral auxiliary and aziridine ring opening with simultaneous protection of the amino groups as the N-Boc derivatives.     

Stereocontrolled synthesis of 3-amino-2-hydroxyalkyl diphenylphosphine oxides mediated by chiral azetidinium salts and epoxyamines

The stereocontrolled synthesis of amino hydroxyalkyl diphenylphosphine oxides has been achieved starting from (2S,3S)-N,N-dibenzyl-3-hydroxy-2-methylazetidinium bromide or (1R),[1′(S)-(dibenzylamino)ethyl]oxirane. The regioselective ring opening of both heterocyclic systems at the less substituted carbon atom with phosphorus nucleophiles proceeded with full stereochemical integrity.     

Synthesis of a water-soluble chiral NMR shift reagent: (S)-PDTA

A five-step synthesis of the water-soluble chiral polydentate ligand, (S)-PDTA [(S)-PDTA = N,N,N′,N′-tetrakis[(hydroxycarbonyl)methyl]-(S)-1,2-diaminopropane] starting from l-alanine has been worked out, via steps with retention of chirality. Total yield is 50.7% (average of ～88% for each step), while published methods report 33.4% total yield over four steps.     

Sodium borohydride-iodine mediated reduction of γ-lactam carboxylic acids followed by DDQ mediated oxidative aromatisation: a simple approach towards N-aryl-formylpyrroles and 1,3-diaryl-formylpyrroles

A simple methodology for the conversion of substituted N-aryl-γ-lactam 2/3-carboxylic acids to substituted N-aryl-2/3-formyl-pyrroles has been developed. Several N-aryl-γ-lactam 2/3-carboxylic acids were reduced to substituted (N-aryl-pyrroliden-2/3-yl)-methanols in good yields by using the NaBH₄-I₂ system. Aromatisation and in situ oxidation of these alcohols using DDQ produced N-aryl-2/3-formyl-pyrroles, which act as key starting material and intermediates in the synthesis of several bioactive compounds.     

Synthesis of novel 1,7-annulated 4,6-dimethoxyindoles

A range of new 1,7-annulated indole derivatives has been prepared via a ring-closing metathesis approach starting from N-allyl-7-formyl indoles.     

Synthesis of chiral isoquinuclidines and determination of their absolute configuration

A route to 1,2-dihydropyridines N¹-substituted with chiral auxiliaries has been developed starting from commercially available chiral amines. Cycloaddition between these dihydropyridines and methyl acrylate gave, in moderate d.e., isoquinuclidines of good enantiomeric purity whose absolute configuration has been established.     

A convenient one-pot synthesis of trisubstituted 1,3,5-triazines through intermediary amidinothioureas

A thiophile-promoted one-pot synthesis of trisubstituted 1,3,5-triazines starting from isothiocyanates, N,N-diethylamidines, and carbamidines has been studied. The reaction proceeds through the formation of intermediary amidinothioureas, which react with carbamidines in the presence of mercury(II) chloride to generate the desired 1,3,5-triazines in good to moderate yields (40-70%).     

Preparation of dimethyl (R)- and (S)-2-(2-aminophenyl)-2-hydroxyethylphosphonate from anthranilic acid

An efficient synthesis of both enantiomers of dimethyl δ-amino-β-hydroxyethylphosphonate 6 has been achieved starting from anthranilic acid, through the resolution of dimethyl (±)-2-(2-N,N-dibenzylaminophenyl)-2-hydroxyethylphosphonate 9 with (S)-O-methylmandelic acid. The absolute configuration of the enantiomers 9 was assigned by the Dale and Mosher approach using the extended Newman projections and molecular mechanics.     

Imidazole derivatives as the organic precursor of ZnO nano particle

N₁-Hydroxy-2,4,5-trisubstituted imidazoles were synthesized starting from 1,2-diketones. The crystal structure of 4,5-dimethyl-2-(3-nitrophenyl)-1H-imidazol-1-ol has been determined. An unusual intermolecular hydrogen bonding through the association of water molecule has been reported. These imidazole derivatives can be thought of as the organic precursor for the synthesis of zinc oxide nano particles.     

Asymmetric synthesis of both diastereomers of protected S-methyl-l-cysteine and S-n-propyl-l-cysteine sulphoxides

The preparation of both isomers at sulphur of N-(benzyloxycarbonyl)-S-methyl (-propyl)-S-oxo-l-cysteine methyl ester has been carried out using l-cysteine and diacetone-d-glucose (DAG) as starting material and inductor of the chirality at sulphur, respectively.