A direct synthesis of indolocarbazoles via new dinitroterphenyl precursors

The two indolocarbazoles 2 and 4 were synthesized via the reductive ring closure of dinitrodiphenylbenzenes with triethylphosphite as reducing agent in a high boiling solvent. The electrochemical behaviour of the title systems is discussed.     

羧酸直接酰胺化的一个新方法

N, N-二甲基取代酰胺可以方便地由脂肪族或芳香羧酸与四(二甲氨基)硅烷在无水溶剂中反应制得。     

合成α 酮酸的新方法

本文报道了一种新的简便的合成α-酮酸(4)的新方法. 用三氟乙酸酐在4-N,N-二甲基氨基吡啶催化下在二氯乙烷溶剂中和易于制得的2,3-二(三甲基硅氧基)羧酸三甲基硅酯(1)反应生成2,3-二(三氟乙酰羧酸三甲硅酯(2). 向反应混合物中加入吡啶生成2-三氟乙酰氧基-2-烯酸(3). 分别用氢氧化钾水溶液和盐酸处理3得产物4 .     

A new synthesis of some indolecarboxylic acids

1-Substituted isatins are transformed into indole derivatives by means of ethyl chloroacetate. In fact, under the conditions of the Darzens reaction they give two glycidic ester isomers 4 and 5 which, by hydrolysis in alkaline medium, undergo a transposition to indole-2,3-dicarboxylic acids 2 together with minor amounts of indole-3-carboxylic acids 3 . From isatin itself, 2,3-dicarboxyindole-1-acetic acid ( 6 ) was obtained.     

A new synthesis of 5-phenylmorphans1,2

A new procedure for the synthesis of 2-azabicyclo- [3.3.1]nonanes by intramolecular cyclization of 4-acetonyl-2- piperidinecarbonitriles under acidic conditions is described. The procedure allows the preparation of the pharmacologically interesting 5-phenylmorphans and involves the initial formation of 4-acetonylidenepiperidine 4, conjugate addition of a diarylcuprate, and cyclization of the resulting 4-acetonylpiperidine by way of the corresponding 2-cyano derivative.     

A new, direct, and efficient synthesis of benzonaphthyridin-5-ones

Microwave-assisted Suzuki cross-coupling reaction of 2-fluorophenylboronic acid with all orthochlorocyanopyridine isomers allowed the rapid syntheses of key intermediates for anionic ring closure, which was performed using potassium hydroxide under microwave irradiation to give benzonaphthyridin-5-ones in high yields.     

Nitroalkanes as new, ideal precursors for the synthesis of benzene derivatives

Nitroalkanes have emerged, in the past few years, as powerful acyclic building blocks to synthesize polyfunctionalized benzene derivatives, avoiding any serious regiochemical ambiguities due to the activating/deactivating and orienting effects of the substituents. Many of these procedures are realized in a one-pot process or a few-step sequence. This feature article describes recent results, mainly from our group, in this field.     

A new, mild one-pot synthesis of iodinated heterocycles as suitable precursors for N-heterocyclic carbene complexes

The use of I₂/AgOAc in dichloromethane constitutes a cheap, mild, and efficient method for the selective iodination of a variety of heterocycles. In a number of cases, this method provides superior yields to other literature methods and affords iodo-functionalized heterocycles that are suitable precursors for carbene complexes.     

Abc amino acids: design, synthesis, and properties of new photoelastic amino acids

Photoisomerizable amino acids provide a direct avenue to the experimental manipulation of bioactive polypeptides, potentially allowing real-time, remote control of biological systems and enabling useful applications in nanobiotechnology. Herein, we report a new class of photoisomerizable amino acids intended to cause pronounced expansion and contraction in the polypeptide backbone, i.e., to be photoelastic. These compounds, termed Abc amino acids, employ a photoisomerizable azobiphenyl chromophore to control the relative disposition of aminomethyl and carboxyl substituents. Molecular modeling of nine Abc isomers led to the identification of one with particularly attractive properties, including the ability to induce contractions up to 13 A in the backbone upon trans --> cis photoisomerization. This isomer, designated mpAbc, has substituents at meta and para positions on the inner (azo-linked) and outer rings, respectively. An efficient synthesis of Fmoc-protected mpAbc was executed in which the biaryl components were formed via Suzuki couplings and the azo linkage was formed via amine/nitroso condensation; protected forms of three other Abc isomers were prepared similarly. An undecapeptide incorporating mpAbc was synthesized by conventional solid-phase methods and displayed characteristic azobenzene photochemical behavior with optimal conversion to the cis isomer at 360 nm and a thermal cis --> trans half-life of 100 min at 80 degrees C.     

A new synthesis of 5-hydroxy-6-methyluracil

Dehydration of 5,6-dihydro-5,6-dihydroxy-6-methyl- and 5,6-dihydro-5,6-dihydroxy-1,3,6-trimethyl-uracil in 0.4 M aqueous sulfuric acid gives 5-hydroxy-6-methyl- and 5-hydroxy-1,3,6-trimethyluracil in quantitative yields. Two possible mechanisms have been examined using the mPW1k/6-311+G(2df,2pd)//mPW1k/6-31+G(d,p) method for the transformation of methylated and non-methylated 5,6-dihydro-5,6-dihydroxy-6-methyluracils into the corresponding 5-hydroxy-6-methyluracils. The first is a hydride C5-C6 shift occurring in concert with the loss of a water molecule and formation of the corresponding protonated 5,6-dihydro-5-oxo-6-methyluracils. The second is an acid-catalyzed dehydration reaction to yield 5-hydroxy-6-methyluracils. The calculations demonstrated that the second pathway was energetically most favorable.     

A new method for the synthesis of chiral beta-branched alpha-amino acids

A new method for the synthesis of chiral beta-branched alpha-amino acids based on a copper-mediated directed allylic substitution reaction with Grignard reagents is reported. This is the first case in which a delta-stereogenic center is controlling the diastereoselectivity of an o-DPPB-directed allylic substitution. Depending on the alkene geometry of the starting material either diastereomer, anti or syn, is accessible with good levels of acyclic stereocontrol.     

The synthesis of di(aminoguanidine) 5-nitroiminotetrazolate: some diprotic or monoprotic acids as precursors of energetic salts

Syntheses of salts with 4,6-bis(nitroimino)-1,3,5-triazinan-2-one (DNAM), 3,5-dinitro-1,2,4-cyclopentanetrione (DDCP), 3-nitroiminotriazolate, and 5-nitroiminotetrazolate as anions yielded moderately dense nitro-containing energetic salts that are thermally stable to >200 degrees C (measured by thermogravimetric analysis). Di(aminoguanidine) 5-nitroiminotetrazolate (8) crystallizes in the monoclinic space group P2(1)/c with an essentially planar 5-nitroiminotetrazolate dianion. Based on experimental and calculated densities, and theoretical calculations carried out by using the Gaussian 03 suite of programs, all of the salts have calculated detonation pressures and velocities that exceed those of 2,4,6-trinitrotoluene (TNT) and a few have values that approach those of triaminotrinitrobenzene (TATB).