A novel synthesis of 1-aryl-3-piperidone derivatives

A novel method to construct the 1-aryl-3-piperidone scaffold is described here. Starting from 3,5-dichloroaniline, a seven-step synthesis, without the use of protecting groups, generates the desired 3-piperidone ring in an overall yield of 30% through a key Morita–Baylis–Hillman reaction and ring-closing metathesis, providing easy access to diverse and useful heterocycles.     

Straightforward preparation of enantiopure 3-amino-4,4-dimethylpyrrolidin-2-one and its derivatives

An easy access to both enantiomers of 3-amino- and 3-(dimethylamino)-4,4-dimethylpyrrolidin-2-one from rac-pantolactam using (R)-α-methylbenzylamine as a chiral auxiliary is described.     

1-Methyl-3-piperidone and 1-methyl-3-pyrrolidone derivatives from a dieckmann reaction

Attempts to prepare 1-methyl-5-carbethoxy-3-piperidone by a Dieckmann cyclization led to formation of its diethyl ketal on workup. The five-membered ring system, 1-methyl-4-(ethoxy-carbonylmethyl)-3-pyrrolidone was also formed in the cyclization.     

Acid-catalyzed rearrangement of 1-benzyl-2-methyl-3-piperidone to 1-benzyl-2-acetylpyrrolidine

We report that 1-benzyl-2-methyl-3-piperidone, conveniently prepared from 3-hydroxy-2-methylpyridine, undergoes rearrangement to 1-benzyl-2-acetylpyrrolidine in aqueous 6 N HCl at reflux. Studies showing that the 2,2-dimethyl analog is inert under the same conditions support a mechanism of reversible tautomeric equilibria via ring-opened intermediates, one of which was independently synthesized and shown to be a kinetically competent intermediate to product.     

Synthesis of derivatives of 2-amino-3-ethoxycarbonylthiophene

A number of alkylidene esters are synthesized from the corresponding ketones and cyanoacetic ester, and treatment of the esters with sulfur in the presence of a catalytic amount of diethylamine gives 2-amino-3-ethoxycarbonylthiophene derivatives.     

Synthesis of derivatives of 2-amino-3-ethoxycarbonylthiophene

A number of alkylidene esters are synthesized from the corresponding ketones and cyanoacetic ester, and treatment of the esters with sulfur in the presence of a catalytic amount of diethylamine gives 2-amino-3-ethoxycarbonylthiophene derivatives.     

Novel benzopyranopyridine derivatives of 2-amino-3-formylchromone

Enol lactones such as 4-hydroxy-6-methyl-2H-pyran-2-one (triacetic acid lactone, TAL) and 4-hydroxycoumarin when treated with 2-amino-3-formylchromone under basic conditions afforded 3-acetoacetyl benzopyranopyridones and benzopyranopyridines, respectively. A series of pyrazole derivatives was prepared by the reaction of 3-acetoacetyl benzopyranopyridones with different hydrazines. All compounds were characterised on the basis of spectral data and their antibacterial activity evaluated.     

Antibacterial activity of 2-amino-3-cyanopyridine derivatives

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Synthesis of 2-amino-3-fluoroacrylic acid containing peptides

[reaction: see text] Peptides containing (E)- and (Z)-3-fluorodehydroalanine have been prepared from serine via a fluoro-Pummerer rearrangement. The resulting electrophilic moieties may be useful affinity labels for the identification of the targets of dehydroamino acid containing natural products that act by covalent mechanisms.     

2-氨基-3-羟基环戊烯-1-腈衍生物的合成和晶体结构

用低价钛试剂(TiCl~4-Zn)与α,α-(4-氯苯基)(二氰甲基)甲基苯基酮反应合成了非对映消旋体(3R,5S;3S,5R)和(3R,5R;3S,5S)2-氨基-3-羟基-3-苯基-5-对氯苯基环戊烯-1-腈。并用X射线衍射分析确定了这两个非对映异构体的构型。     

A new route to 2-amino- or 2-hydroxy-3-pyridinecarboxylic acid derivatives

Schiff's bases derived from ketones and t-butylamine ( 1 ) reacted with methyl methoxymethylenemalonate to give 2-hydroxy-3-pyridinecarboxylates. Similarly, treatment of 1 with ethoxymethylenemalononitrile gave 2-amino-3-pyridinecarbonitriles. Compounds 1 on reaction with ethyl 2-cyano-3-ethoxypropenoate afforded 2-amino-3-pyridinecarboxylates.     

On the conversion of 1-glutamate to 1-dopa : The preparation and chemistry of 1-methoxy-2-acetoxy-3-trimethylsilyloxy-1,3-butadiene

The title diene was prepared by the enol silylation of 1-methoxy-2-acetoxybut-1-ene-3-one. It undergoes Diels-Alder cycloaddition with a variety of dienophiles. Through such cycloaddition ther is provided acess to regiospecifically monoderivatized diosphenols and catechols. Cycloaddition of the title compound with dienophile (28), derived from L-glutamate, provides a route to optically pure L-Dopa.     

Enantiodivergent synthesis of 3-amino-4,4-dimethyl-1-phenylpyrrolidin-2-one and derivatives: amino analogues of pantolactone

An enantiodivergent preparation of (+)-(R)- and (−)-(S)-3-amino-4,4-dimethyl-1-phenylpyrrolidin-2-one, (R)- and (S)-9, and several derivatives, from 4,4-dimethyl-1-phenylpyrrolidin-2,3-dione, 4, and (R)- or (S)-1-phenylethylamine, (R)- or (S)-5, as the chirality transfer agents, is described. Amine (S)-9 has also been used as a chiral auxiliary in a diastereoselective Michael reaction.     

Asymmetric synthesis of 2-amino-3-hydroxynorbornene-2-carboxylic acid derivatives

The enantioselective synthesis of 2-amino-3-hydroxynorbornene-2-carboxylic acid derivatives (5) was studied using the Diels-Alder reaction between cyclopentadiene and different dienophiles, i.e., alkyl 5-oxo-2-phenyloxazol-4-methylenecarbonates (1) or 2-benzoylamino-3-alkoxycarbonyloxy-acrylates (12), operating with different Lewis acids and both with thermal and with ultrasound conditions. The enantioselective synthesis of the exo/endo compounds 5c,d and 5'c,d was achieved starting from the chiral menthyl acrylates 12b,c using Mg(ClO(4))(2) as the catalyst and ultrasound. The cycloadducts were obtained in very good yield, in mild conditions, in short time, and in good diastereomeric excess (exo, 80%; endo, 87%). Finally, the use of alkylidene-oxazolones or acrylates and EtAlCl(2) or Mg(ClO(4))(2) as the catalyst allowed control of the cycloaddition reaction in favor of the exo or endo products.