Mohamed I. M. Wazeer

Terpenoid and biflavonoid constituents of Calophyllum calaba and Garcinia spicata from Sri Lanka

Abstract A new bark acid, isochapelieric acid (cis-chapelieric acid), chapelieric acid, friedelin, friedelan-3β-ol, canophyllal, canophyllol, friedelan-3β,28-diol, canophyllic acid and amentoflavone have been isolated and characterized from leaf extractives of Calophyllum calaba. 13CNMR spectra of methyl chapelierate and methyl isochapelierate have been recorded and interpreted. Leaf extractives of Garcinia spicata afforded an unidentified long chain carboxylic acid, friedelin, friedelan-3β-ol, sitosterol and the biflavanones GB-1, GB-1a, GB-2a and morelloflavone. Chemotaxonomic significance of the occurrence of some of the above foliar constituents in Calophyllum and Garcinia species is discussed.

A lupenediol from Euonymus revolutus

Abstract A new lupane derivative isolated from Euonymus revolutus (Celastraceae) has been established to be 2α,3α-dihydroxy-lup-20(29)-en-28-oic acid on the basis of chemical interconversions and spectroscopic data.

The structure of zeylasterone - the first of a new series of phenolic 24-nor-D:A-friedo-oleanan triterpenes

Zeylasterone, a new triterpene from Kokoona zeylanica, is shown to be 2,3-dihydroxy-6-oxo-24-nor-D:A-friedo-oleana-1,3,5(10),7-tetraen-23,29-dioic acid-29-methyl ester (20 α) (1), the first member of a new series of phenolic 24-nor-D:A-friedo-oleanans.

A nuclear magnetic resonance study of some bis(phosphinoyl)amines and bis(phosphinothioyl)amines

1 n H, 31P and 13C N.m.r. spectra have been obtained for a number of bis(phosphinoyl)amines (I) and bis(phosphinothioyl)amines (II). The spectra have been analysed to give chemical shifts and coupling constants, which are presented and discussed here. The sign of 2JPNP has been determined by heteronuclear spin tickling in several cases and found to be positive.

Preparative and nuclear magnetic resonance studies of diazadiphosphetidines. Part V. Chloromethyl compounds of the type [(ClxH3 –xC)F2PNMe]2

A series of chlorinated dimethyl tetrafluorodiazadiphosphetidines, [RF2PNMe]2, where R = ClCH2(I), Cl2HC (II), or Cl3C (III) have been studied. The syntheses of the two new members of this series, (II) and (III), are described. Analyses of the 31P-{1H} and 19F-{1H} noise-decoupled n.m.r. spectra yielded values for chemical shifts and coupling constants. In addition some 1H n.m.r. data are given, including results from computer-fitting for (II). The n.m.r. parameters and isomerism of the compounds are discussed.

Relationships of nuclear magnetic resonance parameters to structure for cyclotriphosphazatrienes

The 19F n.m.r. spectra of a number of fluorinated cyclotriphosphazatrienes were measured and analysed, using iterative fitting by computer, to give the relevant coupling constants and chemical shifts. Some of the 31P spectra were also recorded and used in the computer iteration. The relationships of the n.m.r. parameters with molecular structure are discussed.

Preparative and structural studies of diazadiphosphetidines. Part 9. X-Ray and nuclear magnetic resonance investigations of (Ph2FPNMe)n

It has been established by X-ray and n.m.r. analyses that the compund (Ph2FPNMe)n can be prepared as a dimer with a diazadiphosphetiding ring. The 1H spectrum of the NMe group may be explained in terms of a slow pseudorotation between two conformations. The two values of 3JPH(16.78 and 6.17 Hz) are considerably different, and involve coupling paths through axial and equatorial P–N bonds. Crystals of (Ph2FPNMe)2 are triclinic, space group P, with a= 9.849(2), b= 14.858(3), c= 8.236 (1)A, α= 93.53(2), β= 94.70(2), γ= 104.04(2)°, Z= 2. There are two independent crystallographically centrosymmetric molecules within the unit cell. Distorted trigonal-bipyramidal co-ordination is observed at phosphorus with mean bond lengths; P–F 1.683(3), P–N eq 1.652(3), P–Nax 1.780(1), and P–C 1.835(4)A. The Structure was solved by direct methods and refined to R 0.063 for 3 299 diffractometer-measured unique reflections.

Preparative and nuclear magnetic resonance studies of diazadiphosphetidines. Part VIII. 2,2,2,4-Tetrafluoro-1,3-dimethyl-4-o-phenylenedioxy-1,3-diazadiphosphetidine

The preparation and mass spectrum of the title compound containing a chelating catechol substituent are described. The 31P–{1H} and 19F–{1H} n.m.r. spectra have been analyzed, and the results indicate that the single fluorine attached to the chelated phosphorus atom is basically equatorial rather than axial.

Preparative and nuclear magnetic resonance studies of diazadiphosphetidines. Part VI. 2,4-Dialkyl-2,2,4,4-tetrafluoro-,3-dimethyl-1,3,2,4-diazadiphosphetidines

Proton-decoupled 19F and 31P n.m.r. spectra of a series of dialkyltetrafluorodiazadiphosphetidines. (RF2PNMe)2(I; R = Me, Et, Pri, or But), have been recorded and analysed for temperatures high enough for gauche⇌trans exchange to be rapid on the n.m.r.timescale, and at low temperatures when the exchange is slow. Some 1H n.m.r. data are also given, including the results of a comoplete analysis of the spectrum of (I; R = Me) on an [A(X)2M3]2 basis. Many signs of coupling constants have been obtained either from the spectral analysis or from double resonance experiments. The coupling constants and chemical shifts are compared and discussed. There is a very large isomer effect on 2JPP, especially for the But compound. Isomer populations have been obtained by several methods. The preparations of the Pri and But compounds, not previously reported, are described in detail.

Preparative and nuclear magnetic resonance studies of diazadiphosphetidines. Part VII. Fluorine-19 and phosphorus-31 investigations of chlorofluorodiazadiphosphetidines

Fluorine-19 and phosphorus-31 n.m.r. spectra have been obtained and analysed for a series of compounds of the type [graphic omitted]Me, mostly under conditions of proton decoupling. The data are discussed in relation to substituent effects.