Letters in Organic Chemistry - Volume 7, Issue 4, 2010

An efficient and simple protocol has been developed for the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones by a one-pot three-component cyclocondensation reaction of an aromatic aldehyde, β-ketoester, and urea or thiourea under solvent-free conditions using triethylamine (Et3N) as catalyst for the Biginelli reaction.

Some new spiro[oxindole-quinazoline/pyrimidine]ones were synthesized via a novel three-component Biginelli-like reaction between isatin, cyclic or acyclic 1,3-dicarbonyl compounds, and urea, N-methyl urea or thiourea in one pot and good yields.

Starting from TRIS [2-amino-2-(hydroxymethyl)propane-1,3-diol] via its thia analogue, 2-amino-2- (mercaptomethyl)propane-1,3-diol' double cyclocondensation with formaldehyde, we report a four steps synthesis of the first term in the title series of compounds, bearing the exploitable hydroxymethyl functionality at the C-5 position. Conformational analysis is discussed based on DFT calculations and 1H-DNMR.

3-Acetyl-N-(4-bromophenyl)-4-(diethylamino)selenet-2(2H)-imine (5a), which is conveniently obtained from the formal [2+2] cycloaddition of 4-bromophenyl isoselenocyanate and 4-(diethylamino)-3-butyn-2-one, reacts with amines, alcohols, water, and thiophenol to give the corresponding 2-methylen-3-oxobutane selenoamides 7 in good yields via ring opening to the ketenimine 6 and subsequent addition of the nucleophile.

A simple solvent-free method to prepare four N,N,N',N'-tetra(2-hydroxy-3,5-dimethylbenzyl)diaminoalkanes and four N,N,N',N'-tetra(2-hydroxy-5-t-butyl-3-methylbenzyl)-diaminoalkanes containing a long n-alkyl-bridge (5-8 CH2 groups between N-atoms) is described. In addition, preparations of four dihydrochlorides of prepared n-alkyl-bridged N,N,N',N'-tetra(2-hydroxybenzyl)diamines are described. This method was also tested i Read More

Ceric ammonium nitrate (CAN) catalyzed the one-pot synthesis of 2,2,4-trimethyl-1,2-dihydroquinoline derivatives from substituted anilines and acetone via a modified Skraup reaction. The methodology was used to synthesize a novel dihydroquinoline-based compound derived from an anti-inflammatory agent nimesulide.

A new method is reported for the preparation of 2,3,4,9-tetrahydro-1H-β-carboline-3-carboxylic acid methyl ester, a key intermediate in the synthesis of Tadalafil which is used for the treatment of male erectile dysfunction, via one-pot esterification and Pictet-Spengler reaction.

A general and practical one-pot synthesis of spiro-heterocyclic compounds using diphenylammonium triflate (DPAT, 5 mol%) as a novel and efficient catalyst is described. The pseudo four-components Biginelli-like reaction of 5,5- dimethyl-1,3-cyclohexanedione, thiourea and aldehydes catalyzed by DPAT in refluxing ethanol produced the corresponding spiro-heterocyclic compounds with moderate to good yields. A possible mecha Read More

Diacetyl-L-tartaric acid anhydride reacted with aromatic primary amines to yield imides (3g-l) and amides (4a-f). The ortho-substituted aromatic primary amines either with electron donating or withdrawing groups yielded amides, whereas para-substituted amines produced imides. However, meta-substituted aromatic primary amines with electron withdrawing residues afforded amides while electron donating counterparts fur Read More

A series of 1,5-diaryl-1,4-pentadien-3-one oximes were synthesized via the reaction of 1,5-diaryl-1,4- pentadien-3-one with hydroxylamine hydrochloride in the presence of anhydrous sodium sulfate at refluxing EtOH to give good yields. This method provided several advantages such as shorter reaction time and higher yield.

Formerly, 9-amino-7-methoxy-1,2,3,4-tetrahydroacridine (7-MEOTA) was investigated as promising tacrine analogue beneficial for its low toxicity compared to tacrine. In this study, novel 7-MEOTA derivatives were synthesized — namely - 9,9'-di-(alkane-1,ω-diyldiimino)-di-(7-methoxy-1,2,3,4-tetrahydroacridine) was prepared from the corresponding diiodoalkanes. The novel compounds exhibit anticholinesterase (acetylcholine Read More

A novel simple three-step synthesis of 3-arylated 5,6-dimethoxybenzo[d]isothiazole 1,1-dioxide is reported. ortho-Lithiation of N-tert-butyl-3,4-dimethoxybenzenesulfonamide followed by reaction with aryl aldehydes gave carbinol sulfonamides, which were oxidized into ketosulfonamides and converted to the ketimines via TMSCl/NaI/MeCN reagent mediated novel cyclization.

2,2,5,7,8-Pentamethyl-6-chromanylamine-15N was prepared by condensation of ZnCl2-catalyzed condensation of 2,3,5-trimethylphenol with isoprene, followed by conversion of the resulting chroman into the 6-nitro-derivative and further reduction to the title compound, which possesses a 2-methyl group instead of the isoprenoid side chain of tocopherols and tocopheramines. Tocopheramines and their short-chain analogue Read More

Antioxidant potential of some β-ionyl compounds has been assessed by examining their ability to protect methyl linoleate from aerial and 2,2'-azobisisobutyronitrile-induced radical-mediated oxidation. It is observed that the π- electron density of β-ionyl structure is an important factor in the antiradical activity of these compounds.

A chiral ionic liquid, 1-butyl-3-methylimidazolium (T-4)-bis[(2S)-2-(hydroxy-κO) propanoato-κO]borate (BMIm+BLLB-), has been used as organocatalyst and asymmetric inducer in Diels-Alder reactions between anthrone and various maleimides. This greener solvent makes the reaction faster, proceeds with quantitative yields and exhibits moderate enantioselectivity. Stereochemical outcome suggests a more or Read More