D.W. Brown

New antioxidants incorporating indole and indoline chromophores

Abstract Syntheses of potent antioxidants utilising indenoindole or indenoindoline pharmacophores are described. The antioxidant behaviour and the oxidation potentials of these compounds are correlated, and some of their reactions with radicals are noted.

Regio- and diastereoselectivity in aldol reactions of cyclopent-2-enone, 2-(5H)furanone and their derived trimethylsilyloxydienes

Abstract Differences in erythro/threo -selectivity were assessed foraldol condensations of aldehydes with the lithium salts of cyclopent-2-enone, 2-(5H)furanone, and for Lewis acid catalysed condensations with the derived trimethylsilyoxydienes.

1,2-dihydroisoquinolines—XI: Further berbine syntheses

Abstract New syntheses of tetrahydroberberine and tetrahydropalmatine are described and some other potential routes to the berbine skeleton are explored.

1,2-Dihydroisoquinolines X : The cyclization of benzylaminoacetaldehyde dialkylacetals

Abstract The cyclization of some benzylaminoacetaldehyde dialkyl acetals has been examined and their utilization for the preparation of various isoquinoline derivatives studied. Some observations on the mechanism of cyclization of these acetals have also been made.

The synthesis of 5-hydroxyberbine derivatives

Abstract The syntheses of 5-hydroxy-2,3,10,11-tetramethoxyberbine (4, R1 = OMe; R2 = OH) and 5-hydroxy-2,3-methylenedioxy-10,11-dimethoxyberbine(4, R1 + R1 = CH2O2R; = OH)aredescribed. The structures have been established by chemical and spectral methods and, in the former case, the relative stereochemistry has been elucidated. These are the first examples of 5-hydroxyberbine derivatives to be prepared.

Mono- and dithionopeptide synthesis

Abstract Syntheses of an endothioenkephalin are described. Additionally the first dithionopeptide has been prepared, and its oxidative transformation into a thiazole has been observed.

Some Diels-Alder reactions with 4-vinyl isoquinoline derivatives

Abstract The first preparation of 4-vinylisoquinoline derivatives is described. 1,4-Cycloadducts have been obtained by their interaction with the dienophiles maleic anhydride, acrylic acid, p -benzoquinone, propriolic acid and benzyne. The structures of the adducts have been assigned on the basis of chemical, but mainly spectroscopic evidence.

1,2-dihydroisoquinolines—VIII : Rearrangement—II☆

Abstract The acid promoted rearrangement of 1-allyl-2-methyl-1,2-dihydroisoquinoline to the corresponding 3-allyl-2-methyl-3,4-dihydroisoquinoline salt has been observed and the behaviour of 1-benzyl-2-methyl-1,2-dihydroisoquinoline and 2-methyl-1,2-dihydropapaverine towards various conditions of acid concentration and temperature has been studied.

1,2-dihydroisoquinolines—XV : Rearrangement III

Abstract The acid-catalysed rearrangement of a 1-allyl-1,2-dihydroisoquinoline into a 3-allyl-3,4-dihydroisoquinolinium salt has been shown to occur in an intra 1-propargyl-1,2-dihydroisoquinoline into a 3-allenyl-3,4-dihydroisoquinolinium salt is also described.

Direct cyanation of the furan nucleus by chlorosulphonyl isocyanate

Abstract A series of furans are converted directly,by reaction with chlorosulphonyl isocyanate, into furancarbonitriles. A route to furfuralcarbonitriles is described involving a new application of the ruthenium dioxide - sodium metaperiodate oxidizing system.