The Nakada Synthesis of (+)-Digitoxigenin
Chemexpress The total synthesis of steroids such as (+)-digitoxigenin (3) has been studied for more than sixty years, yet it has never been thought that such studies would lead to a…
Synthesis of (-)-Colombiasin A and (-)-Elisapterosin B
Historically, there have been three methods for assembling enantiomerically-pure carbocycles: cyclization of an enantiomerically-pure starting material, enantioselective cyclization of a prochiral substrate, and enantioselective transformation of a prochiral cyclic starting…
Transition metal-catalyzed reactions
Jin-Quan Yu of Cambridge University reports (Org. PMID:35567400 Lett. 2003, 5, 4665. DOI: 10.1021/ol0358509) that Pd nanoparticles catalyze the hydrogenolysis of benzylic epoxides. The reaction proceeds with inversion of absolute…
Clean Chemical Synthesis in Water
Green or sustainable chemistry has now attained the status of a major scientific discipline (Green Chemistry: Theory and Practice, 1998, Oxford Press) and the studies in this area have led…
Enantioselective Construction of Arrays of Stereogenic Centers
Sharpless asymmetric epoxidation has long been a workhorse of enantioselective synthesis. The SAE protocol, however, gives only mediocre ee’s with cis allylic alcohols such as nerol (1). PMID:23381626 Hisashi Yamamoto…
Functional Group Protection
Alcohols are the most common functional group protected, and benzyl is the most commonly used alcohol protecting group. Gregory B. Dudley of Florida State University has developed (J. Org. Chem.…
Alternative Strategies for the Construction of Extended Arrays of Stereogenic Centers
Last week (2006 Jan 23), aldol andMannich-based strategies for the catalytic enantioselective construction of extended arrays of aminated, oxygenated and alkylated stereogenic centers were reviewed. This week, the focus is…
Enantioselective aza-Baylis-Hillman Reaction
The aza-Baylis-Hillman (aza-BH) reaction is a nucleophile-catalysed coupling of an imine with an electron-deficient olefin which provides direct access to highly functionalized chiral amines from readily available achiral starting materials.…
Preparation and Reactions of Carboxylic Acids, Esters and Amides
W. Edward Lendsell and Peter N. Preston of Herriot-Watt University, Edinburgh, have developed (Tetrahedron Lett. 2005, 46, 8695. DOI: 10.1016/j.tetlet.2005.10.038)a new family of Pd catalysts, exemplified by the complex 2.…
Carbocycle Construction by the Opening of Strained Rings:Synthesis of Tremulenolide A
Strained three- and four-membered rings can be used to constructlarger rings. The release of the strain energy facilitates bond formation, and the stereochemistry of the small ring can be transmitted…