Current Organic Chemistry - Volume 9, Issue 15, 2005

All the major reactions taking part in the biosynthesis of ajmaline in cell suspension cultures of the Indian medicinal plant Rauvolfia have now been established at the enzyme level. Of the well investigated 10 steps six of the involved enzymes have been functionally cloned. These are strictosidine synthase (STR), strictosidine glucosidase (SG), polyneuridine aldehyde esterase (PNAE), vinorine synthase (VS), cytochrome P450 reduct Read More

A number of monoterpenoid indole and oxindole alkaloids have been isolated from botanical sources, and many of them have been found to possess significant pharmacological activities and are utilized as key lead compounds in new drug development. In this review, the recent results of our phytochemical and synthetic studies of indole alkaloids having the Corynanthe-type related skeleton from genera Uncaria, Nauclea, Read More

The synthetic efforts of the author's research team in several areas within the monoterpene indole alkaloid family are summarized. Most of the work was accomplished in the field of the Aristotelia alkaloids, where some 25 natural products were synthesized for the first time. Systematic investigations on the oxidative rearrangement of indoles to oxindoles and pseudoindoxyl derivatives led to control over the chemoselecti Read More

Indoles that are substituted at the 2- or 3-position with electron-withdrawing groups (nitro, phenylsulfonyl) undergo nucleophilic addition, 1,3-dipolar cycloaddition, and Diels-Alder reactions to give a variety of indoles, pyrroloindoles, and carbazoles. New methods for the synthesis of furo[3,4-b]indoles and the novel ring system furo[3,4- b]pyrrole are described for the first time. Diels-Alder reactions of furo[3,4-b]pyrroles afford Read More

Supported reagents and scavengers have become key tools for the synthesis of biologically important molecular entities. The complexity of the target molecules attainable and the synthetic flexibility afforded by these systems now rivals any solution phase approach whilst offering the added advantage of rapid purification and work-up. This short review highlights the application of these immobilized reagents to the preparatio Read More

Molybdenum and ruthenium alkylidene-catalyzed ring-closing metathesis (RCM) reactions have emerged as key constructs for the facile assembly of the polycyclic frameworks of a variety of natural products. Advances in catalyst development, particularly of highly reactive ruthenium species, have enabled facile ene-ene and ene-yne bond metatheses to create both carbocyclic and heterocyclic systems, sometimes possessing Read More

The marine natural product (-)-palau'amine from the sponge Stylotella aurantium represents one of the toughest challenges to total synthesis. It possesses a strained hexacyclic skeleton which leads current methods of organic synthesis to their limit. Recently, several research groups have undertaken independent approaches, focussing on possibly biomimetic approaches involving the underlying biogenetic key metabolite o Read More

The pyrroloiminoquinone alkaloid family consisting of discorhabdins and makaluvamines exhibits antitumor activities derived from their unique highly-fused structures. The total synthesis of them and the key reactions used in the total synthesis of these compounds are described.

Pyrroles and gem-dihalocyclopropanes are both readily accessible classes of compound. They have considerable potential as building blocks in the construction of alkaloid frameworks. This review details work, carried out within the authors' laboratories, directed towards such ends and with a particular emphasis on the engagement of the title moieties in intramolecular processes. An emerging area involving efforts to exploit t Read More

Using organometallic chemistry several novel methods for the efficient construction of pyrroles, indoles, and carbazoles have been developed. The key reactions are transition metal-mediated or -catalyzed oxidative cyclizations and cycloadditions. In the present article we summarize some recent applications of these methods to short and convergent total syntheses of naturally occurring biologically active alkaloids including Read More