Paul Vogel

A synthesis of αβ-unsaturated aldehydes

The synthesis and the use of 1,3-dioxan-2-ylmethyltriphenylphosphonium bromide (7) in the synthesis of αβ-unsaturated aldehydes is described.

Structure of the lichen depsidone gangaleoidin

As a result of degradative, spectroscopic, and synthetic evidence the structure of the lichen depsidone gangaleoidin is revised to methyl 2,4-dichloro-3-hydroxy-8-methoxy-1,6-dimethyl-11-oxo-11H-dibenzo [b,e][1,4]dioxepin-7-carboxylate. Gangaleoidin was degraded to methyl 3-(2-methoxycarbonyl-5-methoxy-3-methylphenoxy)-4,6-dimethoxy-2-methylbenzoate (10), which was synthesised in 70% yield by Ullmann reaction between methyl 2-bromo-4-methoxy-6-methylbenzoate (22) and methyl 3-hydroxy-4,6-dimethoxy-2-methylbenzoate (30). The bromination of methyl dihydro-orsellinate(23) was studied.

Depsidone synthesis. Part II. Diploicin and gangaleoidin

A new synthesis of the lichen depsidone diploicin (2,4,7,9-tetrachloro-3-hydroxy-8-methoxy-1,6-dimethyldibenzo[b,e][1,4]dioxepin-11-one)(1), and a synthesis of the lichen depsidone gangaleoidin (methyl 2,4-dichloro-3-hydroxy-8-methoxy-1,6-dimethyl-11-oxo-11H-dibenzo[b,e][1,4]dioxepin-7-carboxylate)(2) are described. The key step in both syntheses was an Ullmann reaction.