AN EFFICIENT SYNTHESIS OF PROPARGYLIC PHOSPHONIUM SALTS

Alkylated propargyl bromides react with phosphiaes inacidic tetrahydrofuran solution to give propargylic phosphoniumsalts in good yield.     

AN EFFICIENT SYNTHESIS OF DEOXOQINGHAOSU FROM DIHYDROQINGHAOSU

Deoxoqinghaosu,a more active antimalarial compound thanqinghaosu,was efficiently synthesized from the readily available dihydroqinghaosuwith a new reducing reagent BH_3NEt_3-Me_3SiCl.     

AN EFFICIENT SYNTHESIS OF α-(BENZOTHIAZOL-2-YLOXY)PHOSPHONATES DERIVATIVES

Fifteen title compounds 3a-0 were synthesized by condensationof 2chloro-benzothiazole with a-hydroxyphosphonates in good yields us-ing potassium iodide/tetrabutyl ammonium bromide as catalyst.All new com-pounds have been identified by ~1H-NMR,IR and elemental analysis.     

AN EFFICIENT AND PRACTICAL SYNTHESIS OF α-(1→3)-LINKED MANNOHEXAOSE AND MANNOOCTAOSE

α-(1→3)-Linked mannohexaose and mannooctaose as their methyl glycosides were synthesized from condensation of the corresponding α-(1→3)-linked di- (9) and tetrasaccharide donor (21) with the tetrasaccharide acceptor (23), respectively, followed by deacylation. The donor 21 and acceptor 23 were prepared readily from activation of C-1 of the tetrasaccharide 20 and deallylation of the tetrasaccharide 22, respectively. The tetrasaccharide 20 was prepared from oxidative cleavage of 1-O-p-methoxyphenyl of 19, which was obtained from coupling of 9 with 11. The tetrasaccharide 22 was obtained from condensation of the donor 13 with the acceptor 18. These disaccharides 9, 11, 13, and 18 were produced easily by simple chemical transformation using p-methoxyphenyl 3-O-allyl-α-d-mannopyranoside (1) and 2,3,4,6-tetra-O-benzoyl-α-d-mannopyranosyl trichloroacetimidate (6), and methyl 3-O-allyl-α-d-mannopyranoside (14) as the synthons.     

A CONVENIENT AND EFFICIENT SYNTHESIS OF BIS-IMIDAZOLES

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AN IMPROVED SYNTHESIS OF NIMBIDIOL

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SYNTHESIS AND POLYMERIZATION OF ALIPHATIC TERTIARY AMINO-GROUP N-SUBSTITUTED ACRYLAMIDES

Aliphatic tertiary amino-group N-substituted acrylamides, N-acryl-N′-methylpiperazine (AMP)and N-methacryl-N′-methylpiperazine (MAMP) were synthesized directly from N-methylpiperazinewith corresponding acryloyl chlorides and characterized by elementary analysis of their picrates,~1H-NMR, IR and MS. AMP did not polymerize with benzoyl peroxide (BPO), but could poly-merize with lauroyl peroxide (LPO). The rate equation of the polymerization was given as R_P=K_P [AMP]~(1.5)[LPO]~(0.5) and the overall activation energy of this polymerization system was 10.8Kcal/mol. The redox nature of LPO with the monomer itself was suggested. Even though AMP and MAMP hardly proceed the polymerization initiated with BPO, butunder lower concentration would form redox system with BPO to initiate the polymerization of MMAreadily. The rate equation of the polymerization of MMA initiated with MAMP-BPO systemwas given as R_P=K_P [MMA] [MAMP}~(0.5) [BPO]~(0.5) and the overall activation energy was 10.2Kcal/mol. The analysis of the obtained polymers confirmed that MAMP not only initiated the poly-merization of MMA by combining with BPO, but also took part in the polymer chains impartingthem with better biocompatibility.     

AN ALTERNATE SYNTHESIS OF 4,6-DIHYDROXYQUINAZOLINE

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AN EFFICIENT SYNTHESIS OF ω-(2,2′-BIPYRIDYL)ALKYL ALCOHOLS AND THEIR ACRYLATES

ABSTRACT

ω-(2,2′-Bipyridyl)alkyl alcohols were synthesized by treatment of methyl-2,2′-bipyridine with LDA at ?78°C followed by the addition of ω-bromoalkyl THP ether and hydrolysis of the resulting THP ether. Furthermore, ω-2,2′-bipyridylalkyl acrylates were obtained by the reaction of the corresponding ω-(2,2′-bipyridyl)alkyl alcohols with acryloyl chloride in good yields.     

SYNTHESIS OF AN EPOXY-TERMINATED HYPERBRANCHED AROMATIC POLYESTER

An epoxy-terminated hyperbranched aromatic polyester (P3) was synthesized from a hyperbranched aromaticpolyester containing carboxylic acid end groups (P1), which was derived from the condensation polymerization of the AB_2monomer, 5-acetoxyisophthalic acid. Polymer P1 was converted into the polymeric acid chloride by reaction with thionylchloride. The acid chloride was reacted with ethanol and glycidol to form a poly(ethyl ester) (P2) and an epoxy terminatedmaterial (P3), respectively. The reaction conditions in each step of these processes had to be controlled very carefully toavoid unwanted cross-linking reactions. The characterization of products and intermediates, including molecular weightdistributions and thermal properties, are reported.     

SYNTHESIS OF α-AMINOORTHOESTERS FROM O-TOSYLHYDROXIMATES

ABSTRACT

The abstraction of the acid hydrogen of O-tosylhydroximates 1 by sodium ethylate, then nucleophilic attack of the excess of sodium ethylate at the more hindred carbond atom of azirine 2 and aziridine 3 intermediates to give the α-aminoorthoesters (35–45% yields). The α-aminoorthoester 4a is transformed into α-iminoorthoesters 5a (63% yield) and α-amidoorthoester 6a (65% yield).     

ETEREOSPECIFIC SYNTHESIS OF α-D-FRUCTOFURANOSIDES——SYNTHESIS OF THE OLIGO-FRUCTAN DIASTEREOISOMERS

α-fructofuranosides were stereospecifically synthesized from2-O-Ac-1,3,4,6-O-tetra-benzoylfructose by employing TMSOTf as a catalyst.Meanwhile,one diastereoisomer derivative of sucrose and two of fructanoligomers were synthesized.The structure of all products were confirmed by~(13)C-NMR and ~1H-NMR spectra.     

SYNTHESIS AND CHARACTERIZATION OF AN ORDERED LADDER POLYESTER

An ordered ladder polyester （LPE） was first synthesized through the ladder superstructure （LS） constructed by concerted interactions of hydroxyl- and aramide-based H-bonding and p-terphenyl （TP）-based π-stacking by dehydrochlorination condensation using phosgene （COCl2） as coupling agent. LPE was characterized by GPC, FTIR, NMR, XRD, DSC and AFM. Among them, a distinct image of regularly linear alignment corresponding to the ladder main chain of LPE was first revealed by high-resolution AFM.     

CONCERTED H-BONDING TEMPLATE SYNTHESIS OF AN ORDERED LADDER POLYSILSESQUIOXANE

A novel soluble regular ladder poly（benzoyl-3-aminopropyl） silsesquioxane （LPBAS） was facilely prepared under effective assistance of concerted H-bonding self-assembly of amido groups of side chains and silanol groups, respectively, of a new template monomer [1,3-bis（benzoyl-3-aminopropyl）-1,1,3,3-tetraethoxydisiloxane] （M）. The ordered ladder structure of LPBAS is manifested in： （1） the presence of two Bragg peaks representing the ladder width （d） and ladder thickness （t） in X-ray diffraction （XRD） pattern; （2） narrow base-line width （w = 6） of resonance absorption for -CH2SiO3/2 moiety in 29Si-NMR and （3） high glass transition temperature Tg = 1 12℃ in differential scanning calorimetry （DSC） analysis.     

HIGH YIELD SYNTHESIS OF α-ALKOXYPHOSPHONIUM SALTS AND α-ALKOXYPHOSPHONATES

Abstract

The recent work of Ley et al. ¹ on α-alkoxyphosphorane compounds from cyclic enolethers has prompted us to report our findings in this area. In addition to cyclic enol ethers we have studied the acyclic case as well as the use of phosphite in place of triphenylphosphine. Using this approach we have prepared alkoxy-as well as 5-and 6-membered oxyheterocyclic phosphonium salts and phosphonates in high yield.     

A NEW AND EFFICIENT SYNTHESIS OF 3-IODO DERIVATIVES OF FLAVONES, THIOFLAVONES AND THIOCHROMONES

The title compounds are prepared in good yields by iodination of the corresponding flavones, thioflavones and thiochromones respectively using I_2-CAN(ceric ammonium nitrate) system. The compounds thus prepared are potentially useful precursors for the synthesis of C-3 linked binuclear compounds.     

A STUDY OF ACYLATION OF AN ENAMINE AND A NOVEL SYNTHESIS OF 4-PYRONES

The acylation of 3-pentanone enamine was studied and a novelformation of 4-pyrones from β-diketone enol esters was found involvingan intramolecular O- to C-acyl shift followed by cyclization.     

SYNTHESIS OF 11 α-HYDROXY-AND 11β-CHLORO-ARTEMISININ

11α-Hydroxy-and 11β-chloro-artemisinin have been prepared from artemisinin     

SYNTHESIS AND SPECTROSCOPIC PROPERTIES OF AN AMINO ACID MODIFIED PHTHALOCYANINE

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SYNTHESIS AND REACTIVITY OF SPIROHYDRIDOPHOSPHORANE CONTAINING α-AMINOACETOXY GROUP

Reaction of glycine with phosphorus trichloride in presence of triethylamine hasurnished the ovel spirohydridophosphorane.Its structure has been characterized by elementalanalysis,n.m.r.spectra and mass spectrum.The compound reacted with phenylisothiocyanate togive 2-phenyliminothiazolid-5-one.