Catalytic enantioselective allylation of carbonyl compounds and imines.

The main objective of this review is to provide a comprehensive survey of methods used for stereoselective construction of carbon–nitrogen bonds during the total synthesis of nitrogen-containing natural products that have appeared in the literature since 2000. The material is organized by specific reaction in order of decreasing number of applications in natural product synthesis. About 800 total syntheses of natural products with stereogenic carbon–nitrogen bonds described since 2000 have been reviewed.

Cutting-Edge and Time-Honored Strategies for Stereoselective Construction of C-N Bonds in Total Synthesis.

cis-Delivery of H2 to the π-system of an unsaturated substrate is the canonical course of metal catalyzed hydrogenation reactions. The semireduction of internal alkynes with the aid of [Cp*Ru]-based catalysts violates this rule and affords E-alkenes by direct trans-hydrogenation. A pathway involving σ-complexes and metallacyclopropenes accounts for this unconventional outcome. Connected to this process is an even more striking reactivity mode, in which both H atoms of H2 are delivered to one and the same C atom. Such gem-hydrogenation of stable carbogenic compunds is a fundamentally new transformation that leads to the formation of discrete metal carbene complexes. Computational studies suggest that the trans- and the gem-pathway have similar barriers, but polar substituents in the vicinity of the reacting triple bond provide opportunities for imposing selectivity and control. Moreover, it is shown that catalytic trans-hydrogenation is by no means a singularity: rather, the underlying principle is also ma...

trans-Hydrogenation, gem-Hydrogenation, and trans-Hydrometalation of Alkynes: An Interim Report on an Unorthodox Reactivity Paradigm

This report presents the applications of enantioselective epoxidation of prochiral allylic alcohols, so called ‘Sharpless asymmetric epoxidation’, which is frequently referred as ‘kinetic resolution’. This reaction results in the corresponding 2,3-epoxy alcohols in high stereoselectivity as excellent starting materials for the synthesis of complex targets, such as naturally occurring biologically active molecules.

Applications of Sharpless asymmetric epoxidation in total synthesis

Pharmacological and analytical aspects of bergenin: a concise report

Stereoselective syntheses of 11-α-methoxycurvularin and 11-β-methoxycurvularin

The enantioselective synthesis of 2,6-cis-disubstituted piperidine alkaloids, (2R,6S)-isosolenopsin A 2 and (2S,6R)-isosolenopsin 5 from fire ant venom is described. Starting from the dodecanal and decanal, the synthesis presents two key steps. The first step involves Keck allylation to afford the chiral homoallylalcohol with the required stereochemistry and the second key step consists of Grubbs olefin cross metathesis. The synthesis was achieved in five steps with 44% overall yield.

R. Sateesh Chandra Kumar

Papers

Stereoselective syntheses of 11-α-methoxycurvularin and 11-β-methoxycurvularin

A simple and efficient enantioselective route to 2,6-disubstituted piperidines: synthesis of (2R,6S)-isosolenopsin A and (2S,6R)-isosolenopsin

Synthesis and antiglycation potentials of bergenin derivatives

Stereoselective synthesis of dendrobate alkaloid (+)-241D and its C-4 epimer

Stereoselective synthesis (+)-cephalosporolide D