Indian Journal of Chemistry

Sect. B: Organic Chemistry including Medicinal Chemistry

VOL. 39B

NUMBER 7

JULY 2000

CONTENTS

Review Article

 

 

 

483

Polyhydroxy alkaloids from plants: NMR sheilding behaviour

 

 

 

 

 

 

Neeraj Pant, Dharam C Jain*,

Rajendra S Bhakuni & Ram P Sharma

Polyhydroxy alkaloids comprise a relatively small group of less than 49 members, consisting of five and six membered monocyclic and fused bicyclic ring systems. The majority of them show a general property as glycosidase inhibitors. The NMR shielding data for the polyhydroxy compounds are tabulated and critical spectral features are discussed briefly.

 

 

 

 

Papers

 

 

 

497

Stereochemistry of N-formyl-cis-2,4-diaryl-3-azabicyclo[3.3.1]nonanes

 

 

 

 

 

 

 

 

R Jeyaraman*, J C Thenmozhiyal,

R Murugadoss, M Venkatraj, P Laavanya,

K Panchanatheswaran & M Bhadbhade

The preferred conformations of N-formyl-cis-2,4-diaryl-3-azabicyclo[3.3.1]nonanes have been studied using NMR spectral studies, X-ray crystallography and semiempirical calculations (AM1 and PM3 of MOPAC 6).

 

 

 

 

 

 

504

Ammonium formate catalytic transfer hydrogenation: A convenient method for removal of halogenated benzyloxycarbonyl and benzyl protecting groups in peptide synthesis

 

 

 

 

 

 

D Channe Gowda*, B  Rajesh &

Shankare Gowda

Ammonium formate catalytic transfer hydrogenation in the presence of 10% of palladium on carbon has shown utility for mild and excellent removal of 2-chlorobenzyloxycarbonyl, 2,6-dichlorobenzyl, bromobenzyloxycarbonyl and phenacyl ester from amino acids, peptides and high molecular weight polymers in neutral medium.

 

 

 

 

 

 

509

Acidic hydrolysis of hydroxamic acids in mixed cationic-cationic, cationic-nonionic and anionic-nonionic micelles

 

 

Kallol K Ghosh* & Alka Pandey

Acidic hydrolysis of some carbon and nitrogen substituted hydroxamic acids have been studied at 55°C in mixed micellar solution of surfactants.

 

 

 

 

 

 

 

517

1H NMR spectral study of some 4-hydroxy-2,6-diphenylpiperidines and a systematic analysis of 1H chemical shifts in some piperidines and 3,7-diazabicyclo[3.3.1]nonane derivatives

 

 

 

 

 

 

 

 

 

 

K Pandiarajan*, A Manimekalai &

G Rajarajan

Proton-proton coupling constants and proton chemical shifts have been measured for the title compounds [R1=H, Me, Et, or i-Pr and R2=R3=H; R1=R2=Me and R3=H; R1=R3=Me and R2=H]. The effects of hydroxyl and alkyl groups on the proton chemical shifts are discussed. The proton chemical shifts of 9-hydroxy-3,7-diphenyl-3,7-diazabicyclo[3.3.1]nonane 2a [1,5-dicarbethoxy derivative] and 4a [1,5-dimethyl derivative] suggest that these compounds adopt chair-boat conformations.

 

 

 

 

 

 

525

Structural studies of a polysaccharide isolated from an edible mushroom, Astraeus hygrometricus

 

 

 

 

 

 

 

 

 

 

 

 

 

Amar Pramanik & Syed S Islam*

The repeating unit of the polysaccharide isolated from the aqueous extract of the mushroom is described.

 

 

 

 

 

 

 

530

On the novel cembranoids of the soft coral Sinularia granosa of the Indian Ocean and their biogenesis

 

 

 

 

 

 

 

 

A S R Anjaneyulu*, M J R V Venugopal &

P Sarada

Chemical examination of  the soft coral Sinularia granosa of the Indian Ocean furnishes four novel diterpenoids which include havellockate 4, a seco and rearranged cembranoid derivative. Their possible biogenesis is suggested from a common intermediate.

 

 

 

 

Notes

 

 

 

536

Highly diastereoselective and easy method for synthesis of optically active sulfinate esters from aromatic disulfides

One-step synthesis of chiral aromatic sulfinate esters 2 from aromatic disulfides 1 using lead tetraacetate is reported. The yields are good to excellent and diastereoselectivity is high.

 

 

 

A R Hajipour*, I Mohammadpoor-Baltork &

F Islami

 

 

 

 

539

Synthesis, characterization and reactions of novel cycloketones C6H2(CH2)4(CO)2 and C6(CH2)6(CO)3

 

 

 

 

 

 

 

S S Ullah*, F R Alam & M R Haque

Reactions of AlCl3 with compounds 3 and 5 in refluxing THF are described.

 

 

 

 

 

 

542

Synthesis of new type azo compounds by 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxyl as the phase transfer dehydrogenation catalyst

 

 

 

 

 

 

 

 

 

 

 

 

 

Xiaoyang Wang, Zhiyi Zhang*, Yulu Wang*,

Jianping Li, Cailan Wang & Hong Wang

Use of 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxyl as the phase transfer dehydrogenation catalyst to prepare azo compounds is reported for the first time. Eight N,2-diaryldiazenecarboxamides have been synthesized in high yields under mild condition.

 

 

 

 

 

 

545

A simple, efficient phase-transfer catalyzed method for preparing symmetrical azobenzenes from anilines

 

Using 2,4,6-tri-tert-butylphenol as catalyst, the phase transfer catalyzed method of oxidation of anilines to symmetrical azobenzenes is described for the first time. The ease of the oxidation coincides with the Hammett substituent constants. This report offers an efficient and rapid method to prepare azobenzenes. A possible mechanism of involving free radical oxidation is also suggested.

 

 

Xiaoyang Wang, Yulu Wang*, Jianping Li,

Cailan Wang, Zhifang Duan & Zhiyi Zhang

 

 

 

 

 

 

 

548

Synthesis of different heterocycles using 4-(4˘-methylphenylhydrazono)-1H-pyrano[3,4-b]-benzofuran-1,3-dione

Utility of 3 for the synthesis of benzofuropyridazinones 5-7 and benzofuropyridones 8,9 is described.

 

 

J A Patankar*, Shailesh S Athalye,

Ranjit S Verma & Anita A Dalvi

 

 

 

 

 

551

Heterocyclization of vicinal dioximes to seven membered N, P and O heterocycles

 

 

 

 

 

 

 

 

 

 

 

 

M S Singh* & A K Singh

Synthesis of 2-chloro-5,6-diaryl-2-oxo-P-1,3,4,7-dioxa-diazaphosphepines 3a-d and 2-chloro-P-1,3,4,7-dioxa-diazaphosphipines 4a-d have been carried out in one-pot via dianion intermediates 2.

 

 

 

 

 

 

 

 

554

1,3,4-Oxadiazolines from the reaction of diphenylketene with benzophenone N-diphenylacyl hydrazones. A reinvestigation

 

 

 

 

 

G S Singh*, M Shang & T Ibata

An equimolar reaction of diphehenylketene with benzophenone N-diphenylacyl hydrazones affords 1,3,4-oxadiazolines.

 

 

 

 

 

 

 

557

A facile synthesis of 7-(substituted aryl)-2-benzoyl-3-methyl-5H-furo[3,2-g][1]benzopy­ran-5-ones and their antifeedant activity

The synthesis, characterisation and antifeedant activity of some new furochromones 4 prepared from 4,6-diacetylresorcinol has been reported.

 

P Sampath Rao, K Vishnu Vardhan Reddy &

D Ashok*

 

 

 

560

A new coumarin from the seeds of Calophyllum inophyllum Linn.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Swati P Joshi*, Vinaya B Deodhar &

Usha D Phalgune

A new coumarin 12-methoxyinophyllum-D 1 and six known coumarins have been isolated from the seeds of Calophyllum inophyllum. Structure of 1 has been established by spectroscopic methods.

 

 

 

 

Additions and Corrections

 

 

 

562

Studies on the Himalayan yew Taxus wallichiana: Part VII—Tne taxoids and phenolic constituents of the roots of Taxus wallichiana

 

S K Chattopadhyay, M Kulshrestha,

V Tripathi, G C Saha, R P Sharma &

V K Mehta

 

 

 

 

Authors for correspondence are indicated by (*)