An Efficient Synthesis of 3,4-Dihydro-4-Imino-2(1H)-Quinazolinones

A new one-pot convenient preparation of 3,4-dihydro-4-imino-2(1H)-quinazolinones (4) is described by the reaction of 2-aminobenzonitriles (1) with chlorosulfonyl isocyanate (2), while the reaction of 1 with chlorocarbonyl isocyanate (6) affords ureidobenzonitriles (7), which on thermal cyclization gives 4.     

An Efficient Synthesis of 3-Cyano-1(3H)-Isobehzofuranones

Reaction of o-formyl-N, N-diethylbenzamides (5) with trimethylsilyl cyanide affords the corresponding (0-trimethylsi-lyl)cyanohydrins (6), which on treatment with acetic acid produce 3-cyanophthalides (7) in 80–90% isolated yields.     

Efficient synthesis of novel quinazoline-4(1H)-one derivatives by N-halosulfonamides

Research on Chemical Intermediates - In this research, a facile, effective and one-pot synthesis of new quinazoline-4(1H)-one derivatives is reported. Isatoic anhydride, acid hydrazides or ammonium...     

An Efficient Synthesis of 4,5-Dihydro-3(2H)-pyridazinone Derivatives

Reaction of hydrazine with 5-(2-aryl-2-oxo-ethan-1-yl)-5-R Meldrum's acids 3 gives 4,6-disubstituted 4,5-dihydropyridazin-3(2H)-ones 4 at room temperature. The method is simple and the yield is good. The production of the starting material 3 also is discussed.     

Synthesis of 2,3-dihydroquinazolin-4(1H)-ones catalyzed by a-chymotrypsin

We discovered that a-chymotrypsin has a promiscuous ability to catalyze the cyclocondensation of aromatic and aliphatic aldehydes with 2-aminobenzamides to afford the corresponding 2,3-dihydroquinazolin-4(1H)-ones successfully in high yields(90%–98%) under alcohol solvent. The catalytic activity of a-chymotrypsin was evaluated through investigating the temperature, the enzyme loading and the ratio of substrates in the enzyme-catalyzed reactions. The present method proves to be efficient and environmentally friendly in terms of short reaction time, high yield, green catalyst and the clean products obtained without further purification processes.     

Synthesis of 2,3-Dihydroquinazoline-4(1H)-ones

An efficient, inexpensive, and heterogeneous catalyst, [Al(H₂PO₄)₃], was applied in a three-component, one-pot cyclocondensation reaction of isatoic anhydride with primary amines (or ammonium salts) and aldehydes to afford the corresponding quinazolinone derivatives in excellent yields. Reactions occurred under thermal solvent-free conditions. It was found that this solid acidic catalyst could be easily recovered and reused for at least three cycles without any loss of activity.     

Synthesis of Vinca Alkaloids and Related Compounds. 79. An Intriguing Retro Diels-Alder Reaction(1)

The dimerization products of criocerine (1) are different (2 or 3) depending on whether the reaction is carried out in acetic acid or trifluoroacetic acid. The highly strained product 3 rearranges spontaneously through a retro Diels-Alder reaction. All structures involved were thoroughly investigated by NMR spectroscopic methods.     

An Efficient Synthesis of Highly Optically Active 4-Substituted-2（5H）-furanones from Chiral 3-Bromo-2（5H）-furanone

Highly optically active 4-substituted-2(5H)-furanones 6a-6j were obtained in good yields with de≥98% by the tandem Michael addition/elimination reaction of chiral 3-bromo-2(SH)-furanone (4a), which was conveniently prepared starting from 2-furaldehyde under mild conditions. The products were identified on the basis of their satisfactory elemental analysis and spectroscopic data of IR, UV, ^1H NMR, ^13C NMR and mass spectra. The stereochemistry and absolute configuration of this type of compounds were established by the X-ray crystallographic study. The reaction provided a short and efficient synthesis of the interesting highly optically active 4-subsdtuted-2(5H)-furanones containing an active pyrimidine and a purine base group.     

Synthesis of 1-substituted 3-nitroquinolin-4(1H)-ones

A versatile synthetic method for preparing 1-substituted 3-nitroquinolin-4(1H)-ones from corresponding 2-fluoro-α-nitroacetophenones is demonstrated by the synthesis of 6,7-difluoro derivatives 7a-c . The method involves sequential treatment of the starting nitroacetophenone with triethyl orthoformate and the appropriate amine, followed by a nucleophilic cyclization reaction under mild conditions. The C-7 fluorine atom of 7 can be displaced by cyclic amines. Substituted 6-fluoro-7-(4-methyl-1-piperazinyl)-3-nitroquinolin-4(1H)-ones 8a-c were prepared in this way.     

Synthesis of 1-alkyl-5-phenyl-4(1H)pyrimidinones

1-Alkyl-5-phenyl-4(1H)pyrimidinones are readily synthesized by condensing β-(dimethylamino)-N-[(dimethylamino)methylene] atropamides with methyl or ethyl amine. The latter compounds are prepared from phenylacetamides and dimethylformamide dimethyl acetal.     

An Efficient Synthesis of Racemic 4-Hydroxy-2-oxo-1-pyrrolidineacetamide (Oxiracetam) Using Tetramic-Acid Intermediates

The title compund, 1a , has been synthesised in racemic form from ethyl (E)-4-chloro-3-ethoxybut-2-enoate in 43% overall yield in five steps. Several routes to the final product are described, but the most efficient involves hydrogenation of a C(5)-unsubstituted tetramic acid 5b . The instability of this class of compounds required the use of a catalyst which could operate under very acidic aqueous conditions, a role that was successfully filled by a 5% Ru/C catalyst.     

An Efficient Synthesis of N-(Phosphonoacetylamino)-. Acids

Abstract

In the past 15 years N-(phosphonoacetylamino)-acids have been extensively investigated because of interesting biological activities of the L-aspartic acid derivative (1). In recent years the trimethylsilyl group became more and more important for masking in synthesis of organo-phosphorus compounds as well as natural products.     

Synthesis of 4-Oxo-1,2,3,4-tetrahydropyridine (2,3-Dihydro-4(1H)pyridinone)

N-Ethoxycarbonyl-4-pyridone is reduced to N-ethoxycarbonyl-4-oxo-1, 2, 3, 4-tetrahydropyridine by sodium borohydride in t-butyl alcohol containing ethyl chloroformate. Saponification of the product leads to 4-Oxo-1, 2, 3, 4-tetrahydropyridine.     

Synthesis of 2,3-dihydro-4(1H)-quinoline derivatives

N-Carboxyethyl-N-(3-R-phenyl)-ß-alanines were synthesized by the reaction of m-substituted anilines with acrylic acid; they were cyclized to the corresponding 2,3-dihydro-4(1H)-quinoline derivatives.Translated from Khimiva Geterotsiklicheskikh Soedinenii. No. 4, pp. 523–526, April, 1996.     

Synthesis of benzo-halogenated 4-hydroxy-2(1H)-quinolones

Malondianilides 3 derived from dichloro substituted anilines 2 undergo cyclization to afford 4-hydroxy-2(1H)-quinolones 4 in very good yields using methane sulfonic acid-phosphorus pentoxide as catalyst. 3,4-Dichloro anilines 5 can be shown to yield two isomers, 7 and 8 , whereas 3-substituted anilines 9 afford merely 7-substituted 4-hydroxy-2(1H)-quinolones 11.     

硝酸镧高效催化合成3,4-二氢嘧啶-2(1H)-(硫)酮

报道了以La(NO3)3催化芳香醛、β-酮酯和脲或硫脲-锅法合成3,4-二氢嘧啶-2(1H)-(硫)酮的简单、有效方法.与经典Biginelli反应条件相比,它具有产率高、反应时间短和操作简单等优点.所有目标化合物的结构经元素分析、IR、13C NMR和1H NMR确证.     

Synthesis of 1-Substituted 4(1H)-Quinazolinones Under Solvent-Free Conditions

Abstract

Heating a mixture of 2-(N-alkylamino)benzoic acids, triethyl orthoformate, and ammonium acetate under solvent-free conditions generated 1-substituted 4(1H)-quinazolinones in 73?99% yields. Moreover, a possible reaction pathway was proposed.     

Synthesis of Aristotelia-Type Alkaloids.. Part IV. Synthesis of (±)-aristoserratine

A convergent diastereoselective synthesis of racemic aristoserratine ((±)- 24 ) via an intramolecular iminium-ion cyclization is described. The pivotal imine (±)- 19 was prepared by condensation of the two building blocks (± )-trans-8-amino-3-(2,6-difluorobenzyloxy)-1-p-menthene ((±)- 11 ) and N-(p-methoxybenzenesulfonyl)-3-indo-leacetaldehyde ( 18 ) which were synthesized from (±)-trans-1-p-menthene-3,8-diol ((±)- 7 ) and 3-indoleacetic acid, respectively. On the route to the target (±)- 24 , two previously unknown indole alkaloids have been characterized, namely (±)-‘anti’-hobartin-15-ol ((±)- 22 ) and (±)-‘anti’-aristotelin-15-ol ((±)- 23 ).