Rapid Communications

858

Synthetic studies on tetrastilbenylmethane dendrimers: preparation and optical properties of a second generation dendron

A second generation tristilbenylmethylstyrene dendron is prepared from New Fuchsin. Heck reaction of arenediazonium salts with vinyl trimethylsilane is strategically used to construct the focal styrene unit.

Saumitra Sengupta* &

Subir Kumar Sadhukhan

Papers

863

Synthesis of optically active benzocyclobutene and biphenylene-based unusual a-amino acid derivatives

Optically active benzocyclobutene and biphenylene based unusual a-amino acid derivatives have been prepared via a six step sequence using Schöllkopf chiral auxiliary in a very high diastereoselective manner.

Sambasivarao Kotha* & Somnath Halder

873

Molecular complexity from aromatics: Synthesis of embellished endo tricyclo[5.2.2.0^2,6]undecanes

Vishwakarma Singh* & Dilip K Tosh

876

Tetralone acids as intermediates for the synthesis of podophyllotoxin analogues

Tetralone acids have been synthesised as intermediates for the synthesis of podophyllotoxin analogues

Y B Basavaraju* & C Anjanamurthy

881

Synthesis and characterization of triorganotin esters of heteroaromatic carboxylic acid and crystal structure of ⁿBu₃SnO₂CCH₂C₈H₆N and (PhCH₂)₃SnO₂CC₅H₄N

Fifteen triorganotin esters of heteroaromatic carboxylic acid have been synthesized. Crystal structures of
ⁿBu₃SnO₂CCH₂C₈H₆N and (PhCH₂)₃SnO₂CC₅H₄N have been determined.

R₃SnCl + R¢COONa ¾®R₃SnOOCR¢

Handong Yin*, Chuanhua Wang, Yong Wang, Chunlin Ma & Daqi Wang

889

Synthesis of [dibenzyl(hetero­aromatic­carboxyl­ato)tin(IV)] oxides and crystal structure of [dibenzyl (2-furanylcarboxylato)tin(IV)] oxide

Ten [dibenzyl(heteroaromaticcarboxylato)tin(IV)] oxides have been synthesized by the reaction of heteroaromatic carboxylic acids with the dibenzyltin oxide and characterized by elemental analysis, IR, and NMR spectra. The compounds have been tested against two human tumor cell lines: MCF-7 and WiDr. The results show that some compounds have higher activities in vitro. The molecular structure of [dibenzyl(2-furanylcarboxylato)tin(IV)] oxide 1 is determined by X-ray single crystal diffraction.

(PhCH₂)₂SnO + RCO₂H →{[(PhCH₂)₂Sn(O₂CR)]₂O}₂

Handong Yin*, Chunlin Ma, Yong Wang & Rufen Zhang

895

Effect of aqueous solutions of various alcohols on kinetics of aromatic nucleophilic substitution reaction of 1-fluoro-2,4-dinitrobenzene with piperidine

Effect of aqueous solutions of various alcohols on kinetics of reaction between 1-fluoro-2,4-dinitrobenzene and piperidine has been studied spectrophotometrically at 10°C.

A Habibi Yangjeh* & M R Gholami

900

Synthesis of some new 2,5-disubstituted 1,3,4-oxadiazole derivatives and their biological
activity

In an attempt to prepare compounds incorporating both the coumarin and oxadiazole moieties, three of them having oxadiazole unit directly attached to 3 position of the coumarin, and two having oxadiazole system attached at 7 position through an ether linkage to 4- methyl umbelliferone have been synthesized. All these compounds show good antiinflammatory and analgesic activity. The highest activity is observed in compound carrying p-chlorophenyl substituent. These compounds have been tested for their antimicrobial activity also.

M S Y Khan* & M Akhtar

905

Synthesis and antimicrobial activity of some novel 2,6,7-trisubstituted-2H-3,4-dihydro-1,4-benzoxazin-3-one derivatives

2,6,7-Trisubstituted-2H-3,4-dihydro-1,4-benzoxazin-3-one derivatives I have been prepared and subjected to antimicrobial activity against different gram-positive and gram-negative bacteria and the fungus C. albicans.

R: -OH,-CH₂COOH,-CH₂COOC₂H₅

R₁: -H,-Cl,-CH_{3 ,} R₂:  -H,-NO₂,-CH₃

I

Ismail Yalcin*, Betul P Tekiner,
Ilkay Yildiz Oren, Ozlem Temiz Arpaci,

Esin Aki-Sener & Nurten Altanlar

910

Synthesis and anti-microbial activity of some pyrimidine derivatives

Uracil derivatives are condensed with ethyl bromoacetate to give N₃-b-ethoxycarbonyl derivatives. The hydrazide derivatives of these compounds subsequently react with 1,2-diketones to give corresponding pyrimido pyridazine derivatives.

A K Padhy, M Bardhan & C S Panda*

Notes

916

Optimization of protocols for solid-phase synthesis on a flexible crosslinked support: Synthesis of [Leu⁵]enkephalin

An optimized protocol for the solid-phase synthesis of peptides on high capacity 1,4–butanediol dimethacrylate-crosslinked polystyrene (BDDMA-PS) resin is illustrated by synthesizing [Leu⁵]enkephalin and hydrophobic tripeptides in both free and protected form using t-butyloxycarbonyl (Boc) / benzyl (Bzl) chemistry.

I M Krishna Kumar & Beena Mathew*

921

OsO₄-catalyzed synthesis of  a-amino ketones: improvement of yield and enantioselectivity

Prodeep Phukan

924

Microwave-enhanced Knoevenagel reaction catalyzed by calcium oxide

Calcium oxide is employed both as heterogeneous catalyst and dehydrating agent in microwave-induced Knoevenagel reaction and gives the corresponding arylidene compounds in good yields.

Yanqing Peng & Gonghua Song*

927

Synthesis of isoxazolyl oxadiazolines and thiazolidinones

4-(5-Methyl-3-isoxazolyl)-3,5-diaryl-D²-1,2,4-oxadiazo­lines 2 have been prepared by benzonitrile oxide addition to 3-benzalamino-5-methylisoxazoles. The reaction between these Schiff bases and thiolactic acid provides a mixture of diastereomeric thiazolidinones 3. Similarly the condensation of 4-benzalamino-3-methyl-5-styryl­isoxazoles with thiolactic acid also furnishes a mixture of
diastereomeric thiazolidinones 5.

931

Studies on syntheses of 1-alkyl-2-substituted-thiazolylbenzimidazoles

The reaction of 1-alkyl-2-(a-bromoacetyl-benzimidazoles 3 with substitutedthioureas in DMF at RT gives 1-alkyl-2- substitutedthiazolylbenzimidazoles 4. Alternative syntheses of the title compounds are also described.

P K Dubey*, A Naidu & C Ravi Kumar

935

An efficient chemoselective production of amines from azides using AlCl₃/NaBH₄

A practical reagent system AlCl₃/NaBH₄ is used for the preparation of amines from azides under mild reaction conditions, in excellent yields.

S Raja Ram, K Purushothama Chary,

S Salahuddin & D S Iyengar*

938

The effect of Lewis acidity in carbonyl coupling reactions

Higher Lewis acidity of the catalyst predicts better yield.

Biswajit Purkayastha, Krishna S Deka

(née Krishna Sen) & Dibakar C Deka*

941

Syntheses and biological activities of 2-(3-methylbenzoylamino)-5-aryloxymethyl-1,3,4-oxadiazoles

1-Aryloxyacetyl-4-(3-methylbenzoyl)thiosemicarba­zides 3a-h are synthesized under phase transfer catalysis. Compounds 3a-h on cyclization with mercuric acetate in glacial acetic acid furnish 2-(3-methylbenzoylamino)-5-aryloxymethyl-1,3,4-oxadia­zo­les 4a-h. The preliminary activities of 4 on promoting wheat growth are tested.

Zheng Li,  Xicun Wang* &

 Xiuchun Wang

944

Pentahydroxycholestenone derivative from Eastern Himalayan yew

A new pentahydroxycholestenone derivative has been isolated from Taxus baccata from Arunachal Pradesh, India and its structure has been established by extensive use of 1D and 2D NMR spectroscopy.

Vaishali Chakraborty & Manobjyoti Bordoloi*

946

Three new apianen lactones from Dioscorea bulbifera L.

Three new diterpenic apianen lactones have been isolated from the root of Dioscorea bulbifera L. and their structures established..

Shangzhen Zheng*, Zhen Guo, Tong Shen,

Xudong Zhen & Xuwei Shen

950

Two new O- and C-glycosylxanthones from Gentiana tizuensis Franch

Two new xanthone glycosides, 3-O-β-d-glucopyranosyl- 1,6-dihydroxy xanthone 1 and 3-C-β- d-glucopyranosyl-1-hydroxy-7- menthoxyxanthone 2 have been isolated. Their structures have been established by spectroscopic data.

Xuan Tian,Xiuzhi Xu*, Huiying Zhan &

Aili Wang

953

1, 5-Dihydroxy-3, 8-dimethoxyxanthone from Swertia cuneata

A new 1, 5-dihydroxy-3, 8-di­metho­xy­xanthone 1 has been isolated from Swertia cuneata (Gentianaceae) and identified by means of chemical and UV, ¹HNMR , ¹³C NMR and mass spectral data.

1

K S Khetwal*, P S Rajput, Kunal Sajwan,

Shachindra Pathak & Alka Adhikari

956

A rare flavonol glycoside from Aerva tomentosa Forsk as antimicrobial and hepatoprotective agent

From the perianth lobes of A.tomentosa, kaempferide 3-O-(6¢¢-O-acetyl-4¢¢¢-O- a - methylsinapyl)neohesperi­do­side has been isolated which has shown marked antimicrobial and hepatoprotective activities.

B Jaswant , V Ragunathan* & N Sulochana

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