Current Organic Chemistry - Volume 16, Issue 19, 2012

The use of active methylene reagents in asymmetric catalysis allows interesting and wide synthetic applications for the preparation of highly elaborated enantioenriched compounds. In this review, the chemistry in which sulfur groups, such as a sulfone or more recently even a sulfoxide, in the reagent is utilized to activate the α-methylene position towards either an electrophilic or a nucleophilic attack is compiled. The revie Read More

Enantioselective protonation of prostereogenic enol derivatives has been shown to be an attractive route for the preparation of enantiomerically pure carbonyl compounds. Indeed, this strategy can be regarded as a two steps deracemization process starting from racemic carbonyl compounds. It has therefore attracted a lot of research efforts in the last twenty years to design general and efficient catalytic approach Read More

The Horner-Wadsworth-Emmons reaction has evolved in the last years as one of the most powerful and reliable method for stereocontrolled olefin synthesis. The reaction has become a widespread standard tool in natural products total syntheses, providing access to relatively simple as well as highly complex synthetic targets. In this work we present the most representative applications within the field of natural product synthes Read More

Last decades have witnessed the golden rush of organocatalysis, which opened an effective and efficient way to high yielding, metal free, stereoselective strategies toward the synthesis of a plethora of natural products. The present review provides an overview of the current achievements of those organocatalytic methodologies in which active methylene compounds have been used as key intermediates. Ran Read More

The aldol addition of active methylene compounds has been shown to be an important challenge for current organic chemistry, even if the aldol adducts can be particularly useful in the synthesis of complex valuable molecules. Starting from the early unsuccessful attempts employing “standard” methodologies, this review describes the most recent successful one-pot multicomponent procedures and the first examples Read More

Molecules containing 3-substituted isobenzofuranones and isoindolinones skeletons are found in important bioactive compounds and in a number of natural products. As a consequence several synthetic strategies, both asymmetric and non-asymmetric, have been developed. Thus, this review focuses on the main synthetic approaches to obtain these classes of compounds, analysing the common features, the scope and the lim Read More

In the present study, prior MD investigation or Monte-Carlo search, our step-by-step search for the real lowest energy conformers and the properties of taxol (Also called paclitaxel) is presented theoretically. The paper completes the old paper of Ballone and Marchi (JPC A 1999) which carried out LDA calculations on taxol. A total of 216 initial trial structures were generated by all combinations of internal single-bond rot Read More

A new method of the synthesis of 2-(hydroxymethyl-2H-oxazolo[3,2-a]pyrimidin-7(3H)-ones, commonly known as pyrimidine acyclo-2,2'-anhydronucleosides, was developed. Under the Mitsunobu reaction conditions, 5-substituted 1-(3'-alkoxy-2'- hydroxypropyl)uracil derivatives underwent an intramolecular cyclization to the corresponding 2-alkoxymethyl-2,3-dihydro-7Hoxazolo[ 3,2-a]pyrimidin-7-ones. The variou Read More

The bonding evolution in hetero-Diels-Alder (HDA) reactions has been studied by an ELF analysis of the electron reorganization along the HDA reaction between nitroethylene 6 and dimethylvinylamine (DMVA) 9 at the B3LYP/6-31G* level. This cycloaddition takes place along a two-stages one-step mechanism. In the first stage of the reaction, the C1-C6 bond is formed by coupling of two pseudoradical centers positioned at Read More