Microwave‐Assisted Synthesis of Pyrrolo[2,1‐b]thiazoles Linked to a Carbohydrate Moiety

Herein, we describe the synthesis of pyrrolo[2,1‐b]thiazoles substituted on C‐2 or C‐5 with a protected carbohydrate moiety. The new fused bicyclic heterocycles were obtained via thiazole intermediates, and the N‐alkylation step was assisted by microwave irradiation. The new products were completely characterized by physical and spectroscopic techniques. The cytotoxicity and antiviral activity against Junín virus of the methylated derivates was also evaluated.     

Synthesis and Antitumor Activity of Sorafenib Analogs Containing a Tetrazole Moiety

A novel series of diaryl biuret derivatives containing a tetrazole moiety was designed and synthesized.All the target compounds were evaluated for their in vitro antitumor activity against HT-29,HepG2,MCF-7 and A549 cells by MTT assay.Most of them exhibited obvious antitumor activity,and four of them(4a,4c,4h and 7a)were superior to sorafenib in general.Among them,Compound 4h displayed more potent activity than sorafenib in all tested cancer cells.Compound 4c exhibited the most outstanding activity in inhibition of growth of HepG2 cells(IC50=0.55 μmol/L).Further,they both revealed favorable metabolic stability in in vitro assay.Compounds 4c and 4h are promising candidates for further development.     

A Carbohydrate Approach to the Enantioselective Synthesis of 1,3-Polyols

Treatment of per-O-benzoyl-D-glycero-D-gulo-heptono-1,4-lactone (2) with tertiary amines afforded selectively and with good yields the (5H)-furan-2-one derivatives 3, 4, and 5, formed by controlled elimination of one, two, or three molecules of benzoic acid, respectively. The stereochemistry for the exocyclic double bonds of 4 and 5 was determined by means of NMR techniques. Particularly, the furanone 4 was obtained from 2 ( approximately 90% yield) as a mixture of the E and Z diastereoisomers, which were separated by column chromatography or, more efficiently, by HPLC. The catalytic hydrogenation of compounds 4-E and 4-Z took place diastereoselectively, due to the chiral induction of the stereocenter located in the lateral chain. Thus, hydrogenation of 4-E led to a mixture of the 4,5-dihydro-(3H)-furan-2-ones having 3R,5S,2'S (D-xylo, 6) and 3S,5R,2'S (D-arabino, 7) configurations, with 6 as the major product; whereas the 4-Z isomer gave the same mixture, but being 7 preponderant. On hydrogenation of the original 4-E/Z mixture, compound 6 was obtained pure after recrystallization. O-Debenzoylation of 6gave 9, which was reduced with NaBH(4) to the 3,5-dideoxy-meso-xylo-heptitol (11). The peracetate (12) and perbenzoate (13) of the latter were prepared, and the 1-(tert-butyldiphenylsilyl)oxy derivative (16) was also synthesized via the 3'-(silyloxy)-4,5-dihydro-(3H)-furan-2-one 14. Chemoselective reduction of the lactone function of 6 with diisoamylborane gave the 2,5,6-tri-O-benzoyl-3,6-dideoxy-D-xylo-heptofuranose (17). The 3,5-dideoxy-D-arabino-heptitol (18), a diastereoisomer of 11, was also isolated and characterized.     

A Novel Approach to Synthesis of Tricyclic Diterpenoid

A novel approach has been found and the first total synthesis of (±)-Salvirecognine was accomplished by using it. In which intramolecular cyclization and Friedel-Crafts alkylation took place simultaneously to afford key intermediates for synthesis of aromatic tricyclic diterpenoids OMe PPA O O O OMe 1 2 Scheme 1 As shown in Scheme 1 intramolecular cyclization and Friedel-Crafts alkylation took place simultaneously when compound 1 was treated by PPA at 125 ℃. In which the i-pr…     

A Simple Access to Carbocyclic Analogs of 2-Deoxy-d-Ribose Having the 3-Hydroxymethylene Moiety Replaced by Heteroatoms

Abstract

(2S,4S)-1-O-Benzyl-2,5-di-O-mesyl-4-O-methoxymethylpentan-1,2,4,5-tetrol, a versatile precursor for subsequent cyclisations with bivalent nucleophiles, was obtained in five steps from the easily accessible (3S,5S)-3-hydroxy-5-hydroxymethyldihydrofuran-2(3H)-one. Using diso-dium phosphide in DMSO or disodium selenide in acetone-water, (2R,4S)-2-benzyloxymethyl-4-O-methoxymethylphospholane and (2R,4S)-2-benzyloxymethyl-4-O-methoxymethylselenolane were prepared. The phospholane was oxidized by oxygen (hydrogen peroxide) to give the analogous cyclic phospholane oxide (phosphinic acid) which was then transformed with benzyl bromide and alkali carbonate into the 1-benzyl phospholane oxide (phosphinic acid benzyl ester). All heterocyclic compounds sythesized, formally resemble carba-2,3-dideoxy-d-giycero-pentofuranose, the carbocyclic analog of 2-deoxy-α-d-ribofuranose.     

Synthesis of Novel Azo Dyes Containing the Thiophene Moiety

A series of disperse dyes have been synthesized by diazotation of 2-aminothiophene derivative and coupling with various N-arylmaleimides. The dyes were characterized by IR spectral studies, visible absorption spectra, and elemental analysis. The dyeing performance of these dyes was assessed on nylon fabric. These dyes were found to give yellowish brown to reddish violet shades on dyeing with very good depth, levelness, and brightness on fabric. The percentage dyebath exhaustion and fixation on fabric was found to be very good. The dyed fabric showed poor light fastness and good to excellent fastness to washing, rubbing, perspiration, and sublimation.     

Synthesis of Novel Cyclodextrin Dimers Linked by Multidentate Coordination Units

Cyclodextrins(CDs)ethibitmolccularrecognitionandinclusioncatalysiswhichresemblethatofenzyInes,'buttheirbindingabilitiestoguestmoleculesareusuallyweaker.OnewayofsolvingthisproblemistointroduceanotherCDasanadditionalbindingsitetoformaCDdimer.SuperiortosingleCDderivativesinmolecularrecognitionandbindingabilitytosubstrate,theserecentlyemergingCDdimersareshowingprondseasmoresophisticatedenZymembocs.2AnumberofCDdimershavebeenpreparedtoinvestigatethebindingpropertiestoguestmolecules.However,syn…     

A Simple and Efficient Process for the Synthesis of Novel Heterocycles Containing Benzofuran Moiety Using Thiocarbohydrazide as a Precursor

A simple and efficient process for the synthesis of novel heterocycles starting from thiocarbohydrazide was reported. Reaction of 2‐acetylbenzofuran ( 1 ) and thiocarbohydrazide ( 2 ) in ethanol containing acetic acid produced the corresponding thiocarbohydrazone 3 in 86% yield. Reaction of 3 and isatin ( 4 ) gave N,2‐bis(2‐oxoindolin‐3‐ylidene)hydrazine‐1‐carbothiohydrazine ( 6 ) in 65% yield, rather than the expected product, 3‐[(1‐methyl‐1‐benzofur‐2‐ylmethylidene)amino]‐1‐{[(3Z)‐2‐oxo‐2,3‐dihydro‐1H‐indol‐3‐ylidene]amino}thiourea ( 5 ). Reaction of 2‐((3‐(benzofuran‐2‐yl)‐1‐phenyl‐1H‐pyrazol‐4‐yl)methylene)hydrazine carbothioamide ( 9 ) and chloroacetic acid or hydrazonoyl chloride 11 in basic medium gave (Z)‐2‐((E)‐((3‐(benzofuran‐2‐yl)‐1‐phenyl‐1H‐pyrazol‐4‐yl)methylene)hydrazono)thiazolidin‐4‐one ( 10 ) or 2‐((E)‐2‐((3‐(benzofuran‐2‐yl)‐1‐ phenyl‐1H‐pyrazol‐4‐yl)methylene)hydrazinyl)‐4‐((E)‐(4‐fluorophenyl)diazenyl)‐5‐methylthiazole ( 12 ) in 62% or 74%, respectively.     

A New Approach for the Synthesis of Highly Substituted Aromatic Rings: The Alkyne‐Mediated Approach

Pentasubstituted aromatic rings serve as templates for drug design and can be conveniently prepared by the thermolysis of suitably substituted alkynes under microwave conditions.     

A Novel Approach for the Synthesis of Furopyrimidine and Oxobenzofuran Derivatives

A novel, efficient one‐pot approach for the synthesis of furopyrimidine and oxobenzofuran derivatives 4 by a multicomponent reaction of an isocyanide, an aldehyde, and a CH‐acid compound in CH₂Cl₂ is reported (Scheme 1 and Table). The reactions were completed after 20 h at room temperature. This method has the advantages of high yields, simple methodology, and easy workup.     

Synthesis and Crystal Structure of a Novel Aminothiourea Derivative Bearing Sugar Moiety

5-O-Benzoyl-1,2-O-isopropylidene-α-D-erythro-ketofuranose-3-ulose-3-aminothiose 3 was synthesized and characterized by spectral analysis, and its crystal structure was determined by X-ray diffraction analysis. The crystal belongs to orthorhombic, space group P212121 with a = 6.6276(13), b = 10.993(2), c = 25.027(5) , β = 90°, V = 1823.4(6)3, Z = 4, C16H20N3O5S, Mr = 366.41, Dc = 1.335 g/cm3, μ = 0.208 mm-1, F(000) = 772, S = 1.007, the final R = 0.0465 and wR = 0.1061 for 3251 observed reflections (I > 2σ(I)). Four hydrogen bonds are observed. The absolute configuration of this molecule was confirmed by comparing with that of the original material.     

含有联萘环结构的新型环氧树脂的合成与性能研究

以2-萘酚为原料,先合成出2,2?二羟基-1,1?联萘,再合成出一种新型的具有联萘结构的环氧树脂(BEBN)。通过红外光谱研究了树脂的结构,推测了树脂合成的机理,并对树脂的性能作了一定的研究。该树脂的固化物表现出良好的热性能及力学性能。     

A Novel Approach to the Synthesis of 1,3,4-Thiadiazole-2-amine Derivatives

The main purpose of the study was the development of a new method for synthesis of 1,3,4-thiadiazol-2-amine derivatives in a one-pot manner using the reaction between a thiosemicarbazide and carboxylic acid without toxic additives such as POCl₃ or SOCl₂. The reaction was investigated in the presence of polyphosphate ester (PPE). It was found that, in the presence of PPE, the reaction between the thiosemicarbazide and carboxylic acid proceeds in one-pot through three steps with the formation of corresponding 2-amino-1,3,4-thiadiazole. Using the developed approach five, 2-amino-1,3,4-thiadiazoles were synthesized. The structures of all compounds were proven by mass spectrometry, IR, and NMR spectroscopies.     

新型含吲哚基噻唑烷硫酮化合物的合成及其光学性质

以吲哚-2-甲酸为起始原料,经酰氯化后在三乙胺作用下与2-噻唑硫酮经缩合反应合成了一种新的含吲哚基噻唑烷硫酮化合物(3),其结构和光学性质经UV-Vis, FL, ¹H NMR, IR和X-射线单晶衍射表征。结果表明：3的最大吸收波长位于315 nm;在312 nm波长激发下,3在正己烷中的最大发射波长位于401 nm,荧光量子产率为0.16;在305 nm波长激发下,3的固体荧光最大发射波长位于476 nm。     

A Novel Route to the Fused Maleic Anhydride Moiety of CP Molecules

A seven‐step cascade reaction —in which selective mesylation, epoxide formation, epoxide lysis, cyclization, reiterative oxidation, and nitrogen–oxygen exchange occur sequentially—facilitates the construction of the maleic anhydride moiety of CP molecules 1 and 2 (>93% yield per step). Unstable intermediates of this reaction sequence were detected, providing evidence for the proposed mechanism and resulting in the discovery of a new chemical entity.