Current Organic Synthesis - Volume 4, Issue 2, 2007

We have synthesized (Ra*)-(R*)2-2,2'-bis(1-hydroxy-1H-perfluoroalkyl)biphenyls, axially dissymmetric ligands with two chiral centers. Their titanium complex induces high enantioselectivity in the reaction of an aldehyde with dialkylzinc. Other reactions of these ligands as a chiral ligand or a chiral auxiliary will be presented. The ligand with long perfluoroalkyl sidechains can be extracted selectively with a fluorous solvent such as perfluorohexane. This enables it to be recovered easily by a fluorous phase separation technique and to be used repeatedly.

Most of rhenium complexes are stable with different oxidation states and moisture-, air-tolerant, these remarkable properties result in the diverse applications of them in catalytic organic synthesis as homogeneous catalysts. The purpose of this review is to summarize the recent development of rhenium-catalyzed organic synthesis focusing on the formation of carboncarbon, carbon-heteroatom (C-Si, C-N, C-O, C-S) bonds, functionalization of carbon-hydrogen bond, oxidation and reduction reaction, oxygen and sulfur transfer, photoreduction of carbon dioxide, as well as polymerization, etc.

This review covers different synthetic routes to the C-13 side-chain of taxol the most potent antimicrotubule agent first isolated from Texus bravifolia and later on from several other species of Taxus. The different approaches reported for the syntheses of the C-13 side-chain of taxol are catagorized on the synthetic strategies applied.

Indoles are abundant in nature, and exhibit important biological properties such as anti-inflammatory, antihypertensive, dopaminergic, antineoplastic, anticonvulsant, analgesic, sedative, muscle relaxant, and antimicrobial activities. Synthesis, and functionalization of pharmacologically active indoles continue to receive considerable attention in the field of synthetic organic chemistry. Recent advances toward synthesis of natural, and unnatural indoles have been accelerated by transition metal catalysts, and in the context rhodium has proven to be an extremely useful metal due to its ability to catalyze an array of synthetic transformations with quite often-unique selectivity. This review describes the formation of indoles via rhodium catalyzed C-H, and X-H insertion (X = N, O, and S), cycloaddition, hydroformylation, bimetallic, and asymmetric hydrogenation reactions. Use of solid phase chemistry in rhodium catalyzed indole synthesis has also been discussed in the article.

Quinazolinone alkaloids are a class of natural products possessing a variety of biological activities. In addition, the quinazolinone core scaffold has been extensively utilized as a drug-like template in medicinal chemistry and considered a privileged structure. We have devised a novel, one-pot, highly efficient entry into multiply substituted quinazolinones using microwave technology and applied this methodology to the total syntheses of series of quinazolinone-containing natural products. This review will highlight the total syntheses of these natural products and their analogs under microwave conditions.