Mathias Christmann and co-workers at TU Dortmund University in Germany have reported on the total synthesis of englerin A – a sesquiterpene with highly attractive bioactivity. The seven membered ring was accessed via a ring closing metathesis reaction.
Archive for October, 2009
Jiadifenolide
Posted by naturalproductman on October 30, 2009
Yoshiyasu Fukuyama and co-workers have recently published in Organic Letters on the isolation of two molecules – jiadifenolide and jiadifenoxolane A – with neurotrophic activities.
Posted in Sesquiterpenoids | Leave a Comment »
Alotaketals A and B
Posted by naturalproductman on October 30, 2009
Raymond Andersen’s group at the University of British Columbia has recently reported in Organic Letters on the isolation of a novel sesquiterpenoid structure dubbed alotaketal. This compound and its related structure has cAMP activating abilities with EC50 of 18 and 240 nM. The spiroketal structures were isolated from the marine sponge Hamigera.
Posted in Sesquiterpenoids, Spiroketals | 2 Comments »
Total Synthesis of Vinigrol
Posted by naturalproductman on October 30, 2009
Well it’s been done – vinigrol has been around since 1987 and Phil Baran’s group at Scripps has finally reported the synthesis for the molecule. A key step in this synthesis is the bromonitrile [3+2] cycloaddition to install the methyl-hydroxy equivalent accross an olefin.
Posted in Cycloaddition, Diterpenoids, Methodology | Leave a Comment »
Quinone Reactivities
Posted by naturalproductman on October 29, 2009
Gianluca Sbardela and co-workers at Università degli Studi di Salerno in Italy have recently published in Tetrahedron Letters on a cascade cyclization process involving the use of a alpha-bromo-quinone system.
Posted in Cascade Reactions, Conjugate Additions, Mechanistic, Methodology, Ring forming | Leave a Comment »
Intramolecular Oxy-Michael
Posted by naturalproductman on October 29, 2009
Jayanta Ray and co-workers at IIT Kharagpur have recently published in Tetrahedron Letters on synthesis of polycyclic furans and tetrahydrofurans via an intramolecular oxy-Michael addition using either a reductant or a base to effect the transformation. I think I’ve seen similar substrates but they underwent a hetero-Diels-Alder reaction.
Posted in Conjugate Additions, Methodology, Ring forming | Leave a Comment »
Super Lewis Acid
Posted by naturalproductman on October 29, 2009
Martin Oestreich and co-workers at the Universitat Munster have recently published in ACIEE on the synthesis and use of a cationic silylium ion with a ferrocenyl unit in the backbone. They synthesized the silylium cation via hydride abstraction of a silane using a trityl-borate complex. The catalyst was used to allow for the low temperature setting of the Diels-Alder reaction – ie: -78 degrees Celsius.
Posted in Cycloaddition, Methodology, Ring forming | Leave a Comment »
Look What I Can Do!
Posted by naturalproductman on October 29, 2009
Being able to introduce oxygens to certain positions and take off specific atoms in an already complex looking molecule is just another one of the synthetic chemist’s puzzles. Kazuo Nagasawa and co-workers at the Tokyo University of Agriculture and Technology have recently published in Tetrahedron on manipulating the structure of vitamin D to make different analogues of the compound. When I first saw the transformation, I just knew that they had to use OsO4 to selectively place a hydroxy in the C-1 position.
Posted in Triterpenoids | Leave a Comment »