David B. MacLean

GC/MS examination of four Lycopodium species for alkaloid content

Abstract A GC/MS examination of extracts of Lycopodium clavatum var. borbonicum and L. deuterodensum revealed alkaloids which had not been previously observed in these species. New alkaloids have been found in L. australianum and in L. fastigiatum , two species which had not been investigated before.

Reduction of azides under conditions of desorption-chemical ionization or fast-atom-bombardment mass-spectrometry

Under conditions of desorption-chemical ionization or fast-atom-bombardment mass-spectrometry, the azido groups in some carbohydrate derivatives and other substances undergo apparent reduction to amino groups. Experimental evidence is provided to corroborate the reduction, and possible explanations are proposed for the phenomenon.

A new synthesis of the protoberberine system

Abstract The reaction of phthalide anions with 3,4-dihydroisoquinolines yields 13-hydroxy-8-oxotetrahydroprotoberberines with the hydrogen atoms at C-13 and C-14 trans to one another; reduction of the lactams yields the corresponding 13-hydroxytetrahydroprotoberberines.

13C nuclear magnetic resonance spectra of the spirobenzylisoquinoline alkaloids and related model compounds

The natural abundance 13C nuclear magnetic resonance spectra of a number of spirobenzylisoquinoline alkaloids and related model compounds have been recorded. The carbon resonances of the alkaloids were assigned by comparison with the spectra of other isoquinoline alkaloids and with those of the model compounds. It has been shown that 13C nmr spectroscopy may be used to differentiate between diastereomers in this series.

A new synthesis of spirobenzylisoquinolines. Analogues of sibiricine and corydaine

Abstract The reduction product of dehydrocordrastine, 6 , with di-isobutylaluminum hydride spontaneously rearranged to the spirobenzylisoquinolines 7a and 7b , analogous to the alkaloids sibiricine ( 5a ), corydaine ( 5b ), and yenhusomidine ( 5c ).

Examination of three Siparuna species for alkaloid content

Abstract Examination of the alkaloids of S. dresslerana has revealed the presence of flavinantine and O - methylflavinantine and two unidentified components. Traces of liriodenine were found in the twigs of S. nicaraguensis but no alkaloids were detected in the leaves. Traces of alkaloids were found in the methanolic extract of S. patelliformis but in insufficient quantity for characterization.

Alkaloids of fumaria officinalis

Abstract N -Methylsinactine and dihydrofumariline have been found in a methanol extract of Fumaria officinalis along with a number of other alkaloids previously found in this plant material.

Nuphacristine—an alkaloid from Nuphar luteum

Abstract From the rhizomes of Nuphar luteum a new C 15 alkaloid, nuphacristine, has been isolated. The structure and stereochemistry of nuphacristine have been established on the basis of spectral analysis and chemical transformations.

Enamine precursors of 1-substituted-1,2,3,4-tetrahydro-β-carbolines by way of a Peterson reaction

Abstract Enamines, prepared by way of a Peterson reaction between N b -formyl- N a , N b -dimethyltryptamine and lithio derivatives of aromatic nitrogen heterocycles bearing a trimethylsilylmethyl group α- or γ- to the nitrogen atom, cyclize readily to-β-carbolines.

Diastereoselective Reduction of Derivatives of 3,4-Dihydro-1-methylidene-2-tartaroylisoquinoline

Various enamides were prepared from 3,4-dihydro-6,7-dimethoxy-1-methylisoquinoline by reaction with (R,R)-tartaric acid derivatives. The enamides were reduced with hydrogen over a platinum catalyst to afford diastereomeric mixtures enriched in the (1R)-isomer. The diastereoselectivity of the reduction step was assessed by conversion of the mixtures into N-acetylsalsolidine and measurement of its specific rotation. The enamide, in which the hydroxyl groups of the 2-tartaroyl group are unprotected, cyclizes to an aminal in the presence of acids. The reduction of 5c with sodium borohydride in acidic media afforded a diastereomeric mixture enriched in the (1S)-isomer