A novel and convenient method for the preparation of 5-benzoyl-1,4-naphthoquinone is reported for the first time. The process starts with condensation of malonic acid, followed by Diers–Alder cyclization, methylation, aromatization, hydrolysis, Friedel–Crafts acylation, and oxidation. The new synthesis procedure with high yields does not require special conditions and column chromatographic purification. The method involves readily available reagents and has been demonstrated to be suitable for large-scale preparation.

Novel and convenient synthesis of 5-benzoyl-1,4-naphthoquinone and its derivatives

1. Naturally occurring alkaloid N-oxides are reviewed.2. Examples of indole alkaloid N-oxides from simple indole bases to complex dimeric alkaloids are given.3. Pyrrolizidine alkaloid N-oxides are listed and their toxicity, metabolism and role in the plant considered.4. A brief account of quinolizidine, piperidine and miscellaneous alkaloid N-oxides, together with nicotine N-oxide and N-oxides from micro-organisms, is given.

Alkaloid N-oxides.

Additional alkaloids from Laurelia philippiana and L. novae-zelandiae

Aus Krung Kha Mao (Cyclea barbata Miers) wird als neues Alkaloid ein Tetrandrin-mono-N-2′-oxid (1) isoliert und seine Struktur durch Spektren und Partialsynthese aufgeklart. Zwei weitere Nebenalkaloide wurden als Isochondodendrin (2) und Chondocurin (4) identifiziert.



Alkaloids from the Thai Drug “Krung Kha Mao” (Cyclea Barbata, Menispermaceae), V: Isolation and Structural Elucidation of Further Bisbenzylisoquinoline Alkaloids.



From “Krung Kha Mao” (Cyclea barbata Miers) tetrandrine N-2′-monoxide (1) was isolated as a new alkaloid. Its structure was elucidated by spectroscopy and partial synthesis. Two other alkaloids were identified as isochondodendrine (2) and chondocurine (4).

Alkaloide aus der thailändischen Menispermaceen‐Droge Krung Kha Mao (Cyclea barbata), 5. Mitt. Isolierung und Strukturaufklärung weiterer Bisbenzylisochinolin‐Alkaloide

Constituents of West African Medicinal plants XIX: Funiferine N-oxide, a new alkaloid from Tiliacora funifera (Menispermaceae)

The alkaloid (−)-laurepukine is shown to possess one of the epimeric N-oxide structures 4 or 5. Oxidation of (−)-pukateine (3) by hydrogen peroxide gives (−)-laurepukine and, as a second product, 6-epi-laurepukine.

A. Girardet

Papers

Notiz zur Konstitution des Laurepukins. 8. Mitteilung über natürliche und synthetische Isochinolin-Derivate†‡

Synthèse de quelques acides aminohydroxynaphtoïques susceptibles de posséder une activité tuberculostatique

Natuerliche und synthetische isochinolin-derivate 8. mitt. konstitution des alkaloids laurepukins