Mini-Reviews in Organic Chemistry - Volume 1, Issue 2, 2004

This mini-review discusses the different synthetic methodologies used to synthesize azetidines in enantiomerically pure form, as well as the use of these strained aza-heterocycles as ligands for enantioselective catalysis.

In the last decade there has been a growing interest in the coupling reactions of lactam-derived vinyl triflates and phosphates. The usefulness and versatility of these lactam derivatives in organic synthesis will be highlighted in this review that deals with the methods for their preparation, their stability and reactivity, and applications to the synthesis of natural compounds.

Soil bacteria as well as those infecting other organisms have developed systems to secure iron necessary for their metabolism, which is generally not available in its free ionic form. As one of the possible strategies they learnt to produce secondary metabolites able to bind Fe3+ as water soluble complexes, so-called siderophores. A prominent group of these siderophores are compounds, which contain at least one catecholate unit. A survey of compounds isolated from bacterial cultures will be presented.

Unmodified aldehydes add in 1,4-manner to electron deficient olefins in the presence of a catalytic amount of diethylaminotrimethylsilane. Reaction with methyl α- haloacrylates provided formylcyclopropanecarboxylates by domino conjugate addition-alkylation. Aldol condensation afforded unsaturated aldehydes. The reaction was revealed to proceed via catalytic enamine pathway. Total syntheses of several bisabolane type sesquiterpenoids have been accomplished according to this protocol.

Disease and disorders of the central nervous system (CNS) are some of the most common ailments afflicting mankind, and it has been estimated that 32% of the population of the USA suffers from a disorder of the brain once in a lifetime, and 15% of the population over 18 suffer a mental disorder at least monthly. The use of natural products as psychotropic agents to alleviate mental disorders, or to create altered mental states, probably dates back to the dawn of time, when the first trial-and-error experiments by shamans or other experimenters led to the discovery of the effect of certain plant extracts on the mind. It is thus significant that the first alkaloid to be purified from a plant was the psychoactive analgesic morphine. Although there is extensive literature on the use of plants and plant extracts as hallucinogenic agents, the search for natural products for therapeutic psychotropic purposes is much less well-developed than, for example, the search for anticancer agents. Nevertheless, there are enough examples of the successful search for useful naturally-occurring psychotropic agents to ensure that a continued search is likely to be productive. This review will summarize results in the discovery of CNS-active natural products, with an emphasis on compounds that may be useful for therapeutic purposes.

Most organic lithium compounds exist as aggregates. Many lithium compounds also form mixed aggregates with other lithium compounds, which have structures and properties that are different from either of the parent lithium compounds. Mixed aggregate formation can alter the product distribution and rate of reactions involving lithium dialkylamides.

Calix[7]arenes, of intermediate size between the corresponding hexamers and octamers, are of comparable interest for the synthesis of molecular receptors for medium-sized guests. At this regard current information concerning their synthesis, exhaustive and selective functionalisation, intramolecular bridging, conformational features, and supramolecular properties is reviewed. These data are of particular relevance for the design of new calix[7]arene-based hosts of interesting potentialities in supramolecular chemistry.