No abstract

Improved syntheses of certain O-and N-methyl derivatives of 1,3-dihydroxy-acridone are described. Thermal rearrangement of the appropriate 3-α,α-dimethyl-propargyl ethers in the series yields products which may be methylated to acronycine.

The structure (III) proposed for the hexacyclic alkaloid, himgaline, on the basis of chemical and spectroscopic characterization was confirmed by several partial syntheses of himgaline derivatives from de-N-methylhimbadine (alkaloid G.B. 13). The biogenesis of the Galbulimima alkaloids is discussed.

Three new lignans have been isolated from Himantandra baccata Bail. and one from H. belgraveana F. Muell. Their structures have been elucidated, two are phenyltetralins and the other two are αα?-disubstituted tetrahydrofurans.

The isolation and characterization of 19 new alkaloids from the bark of Galbulimima species is described. After some corrections to previous work, the number of alkaloids from this source now stands at 28.