M. H. G. Munro

Isolation and characterization of diastereomers of discorhabdins H and K and assignment of absolute configuration to discorhabdins D, N, Q, S, T, and U.

Investigations of four different sponge populations of Latrunculia species collected in New Zealand waters has led to the characterization of a new diastereomer of discorhabdin H, named discorhabdin H2, confirmation of the structure of discorhabdin K ((+)-7), and presentation of a new diastereomer, discorhabdin K2 ((-)-8). In each case the structures were established by extensive NMR and MS studies and the absolute configurations interrogated by electronic circular dichroism (ECD). Absolute configurations were assigned to the known metabolites discorhabdins H, D, 2-hydroxy-D, N, and Q by comparison of ECD spectra with those recorded for discorhabdin alkaloids of defined absolute configuration, while the configurations of discorhabdins S, T, and U were assigned by semisynthesis from (+)-(6S,8S)-discorhabdin B.

Occurrence of variabilin in New Zealand sponges of the order dictyoceratida

Abstract Sixty-three collections of New Zealand sponges of the order Dictyoceratida were analysed for the presence of the sesterterpene tetronic acid variabilin. This compound was found only in the morphologically similar genera Ircinia, Psammocinia and Sarcotragus.

Cyclopropane derivatives from the lithium aluminium hydride reduction of methoxyalkynols

Abstract Lithium aluminium hydride reduction of methoxyalkynol(1) yields cyclopropane derivatives (2) and (3), both formed by loss of a methoxy group; a reaction scheme for their formation is presented.

Reactions of propargyl alcohols. VI. Lithium aluminium hydride reductions of 2,2-Dimethyl-3-phenylhex-4-yn-3-ol, its 1-methoxy derivative and 2,2-Di-(methoxymethyl)-3-phenylhex-4-yn-3-ol

Lithium aluminium hydride reductions of 2,2-dimethyl-3-phenyIhex-4-yn-3-ol (5a) and its methoxy (5b) and dimethoxy (5c) derivatives are reported. The nature of the solvent dependence of these reactions is identified, and the mode of formation of the products of the reactions determined.