Mini-Reviews in Organic Chemistry - Volume 5, Issue 1, 2008

Asymmetric vinylogous aldol reaction is a powerful methodology to introduce a multi functional group in the stereoselective manner. Recently, we have developed highly stereoselective vinylogous Mukaiyama aldol reactions using vinylketene N,O-acetals possessing the chiral oxazolidone. Our methodology has been applied to the asymmetric syntheses of natural products to establish the short and efficient routes. This review focuses on the asymmetric vinylogous Mukaiyama aldol reactions using vinylketene N,O-acetals in total syntheses of natural products.

Recent advances in free radical chemistry have expanded the versatility and flexibility of carbon-carbon bond formation in water or aqueous media. This review highlights the substantial progress, which has been made in the last decade to “tame” the reactive free radical species in aqueous phase reactions. This review focused on recent advances in several classes of widely useful free radical reactions in water leading to the formation of C-C bonds. The review will also explore the recent advances in performing stereo-selective free radical reactions in an aqueous medium and its application in synthesis of natural and unnatural amino acids, preparation of novel materials and solid support chemistry. Some practical hints for help design high yielding free radical reactions in aqueous medium are also presented.

In this mini-review, recent chiral receptors bearing polyamine and/or polyamide functional groups are reported. Two main features for their synthesis are the source of the enantiopure nitrogenated synthons and the strategy to assemble the building blocks within the receptor architecture. Combined solutions to both problems have been carried, ranging from chemoenzymatic methods to combinatorial approaches. Topics like conformational control or templation procedures are highlighted. Applications in chiral anion molecular recognition will be also discussed.

The chemical synthesis of proteins, as well as the modification of expressed proteins, requires highly selective reactions. Ligation methods offer feasible tools for this purpose. This mini-review focuses on enzymatic methods for protein ligation; in particular, on the use of the transpeptidase sortase.

This review reports the synthesis and isolation of close to 125 5-haloalkyl substituted 5-hydroxy-4,5- dihydroisoxazoles. The 4,5-dihydroisoxazoles were mainly obtained from the reaction of β-diketones or β-alkoxyvinyl ketones with hydroxylamine, using different reaction conditions and methodologies. The review also reports the 13C NMR data for 109 compounds, the 17O NMR data for 17 compounds, the 15N NMR data for 16 compounds and the 19F NMR data for 36 compounds. The empirical additive substituent increments (SCS) were determined from the experimental 13C, 17O and 15N NMR data.