R. McCrindle

Tetranortriterpenoids—VIII : The constitution and stereochemistry of nimbin☆

Abstract The recorded evidence 3,4 bearing on the constitution of nimbin has been evaluated. By using spectroscopic and additional chemical evidence and making certain biogenetic assumptions, the constitution and stereochemistry (I) are deduced for nimbin. Pyronimbic acid 3 is formulated as XI. The dilactone XVII holds an important place in the structural argument.

Tetranortriterpenoids—VII : [Bicyclononanolides—V] the constitution and stereochemistry of swietenolide☆☆☆

Abstract The constitution and stereochemistry of swietenolide (I) are deduced from its spectroscopic and chemical properties and confirmed b cleavage of the β-diketone VIIa or VIIIa (R  OH) to the mono- and di-carboxylic acids corresponding to XIII and XIV. The absolute configuration of swietenolide as in I follows from the CD of XIII.4

Constituents of Solidago species—I: The constitution and stereochemistry of diterpenoids from Solidago canadensis L.

The constitution and stereochemistry of solidagenone II and the epimeric spiro ethers III from Solidago canadensis L. are deduced from their spectroscopic and chemical properties.

Tetranortriterpenoids—IV : [Bicyclononanolides II] The constitution and stereochemistry of mexicanolide

Abstract The constitution of mexicanolide (I) is deduced from two key reactions. Under very mild basic conditions mexicanolide fragments to form the diketone IVa or Va. This in turn is cleaved by periodate to the triacid X (R = H) and the monoacid XI (R = H) see Part VII. These cleavage products are uniquely defined by their spectroscopic attributes. The absolute configuration of mexicanolide follows from the CD of the diene lactones IVa or Va and XI.

Tetranortriterpenoids—III : 6-Hydroxy- and 6-acetoxy- methyl angolensate from the heartwood of Khaya grandifoliola☆

Abstract Two new tetranortriterpenoids from the heartwood of Khaya grandifoliola are shown to be methyl 6-hydroxy- and methyl 6-acetoxy- angolensate, by analysis of their NMR spectra, using single and double irradiation.

Constituents of solidago species—II : Reactions of solidagenone, the major diterpenoid from Solidago canadensis L.

Abstract Some reductions and rearrangements of solidagenone ( 1 ) are described. These transformations substantiate the structure and stereochemistry previously deduced for 1 .

Tetranortriterpenoids—VI : [Bicyclononanolides IV] swietenolide—the functional groups☆

Abstract The part formulations A and B have been deduced for swietenolide obtained from the seeds of Swietenia macrophylla .

Tetranortriterpenoids—V : [Bicyclononanolides III] the PMR spectrum of mexicanolide☆

Abstract The PMR spectrum of mexicanolide (I) has been examined in detail. In particular the complex spin systems arising from the protons attached to (C-5, C-6) and (C-2, C-30, C-15) have been analysed, using spin-decoupling, spin-tickling and solvent-shift procedures.