Formal Synthesis of the Anti-Angiogenic Polyketide (−)-Borrelidin under Asymmetric Catalytic Control
作者:Ashoka V. R. Madduri、Adriaan J. Minnaard
DOI:10.1002/chem.201001284
日期:——
potent anti‐angiogenesis activity. This paper describes its formal totalsynthesis by the most efficient route to date. This modular approach takes optimal benefit of asymmetric catalysis and permits the synthesis of analogues; in addition, the high yields and selectivities obtained eliminate the need for separation of stereoisomers. The upper half of borrelidin has been accessed by iterative copper‐catalysed
An iterative, facile stereoselective synthesis of C1-C11 fragment of borrelidin via enzymatic desymmetrization strategy
作者:Jhillu Singh Yadav、Nagendra Nath Yadav
DOI:10.1039/c3ra22754e
日期:——
A highly stereoselective and general method for the synthesis of the C1-C11 fragment of borrelidin has been achieved. The main feature of our synthetic route is enzymatic desymmetrization to create two methyl bearing chiral centres, use of Evans auxiliary to introduce two other methyl groups and creation of C3 stereocentre by regioselective opening of an epoxide arising from Sharpless epoxidation protocol. The synthesis of the C1-C11 subunit was achieved in gram scale by a linear synthetic sequence in an overall yield of 18.4%.
The total synthesis of borrelidin has been achieved. The best feature of our synthetic route is macrocyclization at C11-C12 for the construction of an 18-membered ring after esterification between two segments. A detailed examination of the macrocyclization led us to the samarium(II) iodide-mediated intramolecular Reformatsky-type reaction as the most efficient synthetic approach. The two key segments were synthesized through regioselective methylation, directed hydrogenation, stereoselective Reformatsky-type reaction, and MgBr2 center dot Et2O-mediated chelation-controlled allylation.
The totalsynthesis of borrelidin has been achieved. The best feature of our synthetic route is SmI(2)-mediated intramolecular Reformatsky-type reaction for macrocyclization after esterification between two segments. The two key segments were synthesized through chelation-controlled carbotitanation, chelation-controlled hydrogenation, stereoselective Reformatsky reaction, and MgBr(2).Et(2)O-mediated