Stereoselective synthesis of natural products

In another variant of such reactions, the hemi-acetal 104, generated in situ by reaction of the corresponding allylic alcohol with acetaldehyde, undergoes cyclization in the presence of HgClOAc to afford the mercurated acetal 105.128 Under these conditions, the reaction leads to the jy -product with a high selectivity (dr > 10 1 Scheme 14). The same strategy has been applied iteratively for the stereoselective synthesis of natural products containing 1,3,5,7,9-pentaether chains.129... 

P. Potier in Stereoselective Synthesis of Natural Products, proceedings of the Seventh Workshop Conference, Hoechst (W. Bartmann and E. Winterfeldt, eds). Ex-cerpta Medica, Amsterdam, Oxford, 1978. 

Stereoselective synthesis of natural products 88MI55 89MI15,89MI16. 

One of the first apphcations of this reaction in the stereoselective synthesis of natural products exploiting the mechanism-controlled 1,3-chirality transfer appeared in 1991 by Dolle et al. (Scheme 72) [160]. Their retrosyn-thetic analysis of alkaloid 292 ((+)-pinidine) led to a a -synthon 293 which... 

Gennari, C. Rationally designed chiral enol borinates powerful reagents for the stereoselective synthesis of natural products. Pure Appl. Chem. 1997, 69, 507-512. 

From these examples it is clear that the principles of acyclic stereocontrol that govern the allylation reactions of achiral Type II allyl- and crotylmetal reagents with chiral aldehydes can be used to excellent advantage in the stereoselective synthesis of natural products. In the following section, the factors that influence the stereoselective formation of cyclic compounds in the ring-closing allylation reaction are discussed and selected synthetic applications are reviewed. 

Interest in die synthesis of enantiomerically pure compounds is also significant since both enantiomers of the same product often show distinctly different biological activities. In recent decades an enormous effort has been focused on the development of new methods for the stereoselective synthesis of natural products. These methods include a number of approaches for achieving enantioselective transformations of achiral substrates by using chiral auxiliaries, chiral reagents, or chiral catalysts [3]. However, from the range of different synthetic approaches available, the most useful for the synthesis of enantiomerically pure sesquiterpenes is still the hemi-synthesis from readily available natural sesquiterpenes. 

Stereoselective synthesis of natural products, new methods in synthetic organic chemistry, and computational organometallic chemistry in organic synthesis 5-8 highlighted reactions per month, and short reviews of organic, bioorganic, organometallic and microwave chemistry, total synthesis of natural products and multi-component reactions. 

Ut. Brown, in Bartmann Winterfeldt (eds.). Stereoselective Synthesis of Natural Products, p. 62 - 70, Amsterdam Ex-cerpta Medica 1979 Heterocycles 48, 1483 (1998) (biomi-metic interconversions) Phillipson Zenk (eds.). Indole and Biogenetically Related Alkaloids, p. 113-141, 142-184. 185-200, London Academic Press 1980. - [HS293990J... 

SCHEME 12.17 MCAR for the stereoselective synthesis of natural products. 

Johann Mulzer was bom in Prien, Germany in 1944. He received his doctoral degree from the Universitat Miinchen in 1974 imder the direction of Prof. R. Huisgen. He spent one year as postdoctoral fellow at Harvard University with Prof. E. J. Corey working on the LHASA-project. He went back to the Universitat Miinchen where he obtained his ha-bilitation in 1980. In 1982 he was appointed professor at the Universitat Diisseldorf. Since 1984 he has held his present position as Professor of Organic Chemistry at the Freie Universitat Berlin. His research interests are in the field of stereoselective synthesis of natural products and the development of new synthetic methods. 

Since the oxidative addition proceeds with retention of stereochemistry at the double bond, this chemistry can be used for the stereoselective synthesis of natural products like savinin or gadain (Scheme 5-80). ... 

Many successful and imaginative applications of cascade reactions in stereoselective synthesis of natural products and drug-like molecules have been described in this chapter. The gigantic benefits associated with cascade reactions have secured their position in future research and development efforts. In addition to the traditional strategies, such as the metal-catalyzed cascade reactions, recent advances in organocatalysis have expanded the... 

TRANSITION METAL C-H ACTIVATION APPLICATION TO STEREOSELECTIVE SYNTHESIS OF NATURAL PRODUCTS AND DRUGS... 

Transition Metal C H Activation Application to Stereoselective Synthesis of Natural Products and Drugs... 

---