Diastereo- and enantioselective aldehyde addition reactions of 2-allyl-1,3,2-dioxaborolane-4,5-dicarboxylic esters, a useful class of tartrate ester modified allylboronates
Tied back: The title reaction was observed when a silicon‐tethered diene was treated with the Hoveyda–Grubbs second‐generation catalyst. The structural requirements for the E‐olefin‐formingring‐closing metathesis, and the transition state leading to E olefin are discussed. This methodology will be useful in the synthesis of polyketides containing a pent‐2‐ene‐1,5‐diol unit.
Enantioselectivity in the allylboration of N-silylimines with a variety of chirallymodifiedallylboronreagents has been examined. Optically active N-sulfonylamino alcohols (16, 17 and 19) derived from D-camphor and norephedrine were found to be efficient chiral ligands for the allylboration reagent. These reagents smoothly reacted with N-silylimines to give the corresponding homoallylic amines in
A stereoselective totalsynthesis of topsentolide B2, a selective cytotoxic oxylipin against SK-OV-3 and SK-MEL-2 cancer cell lines has been achieved based on asymmetric dihydroxylation, Roush allylation, and ring closing metathesis (RCM) reactions. The synthesis is completed in 11 steps and 2.1% overall yield.
Diisobutylaluminum hydride (DIBAL-H) reduces nitriles to give N-diisobutylaluminum imines, which were asymmetrically allylated with chirallymodifiedallylboronreagents. The corresponding chiral primary homoallylamines were obtained with up to 87% ee.
Studies on the Synthesis of Kijanolide: Synthesis of an Advanced Seco-acid Intermediate
作者:William R. Roush、Hou Chen、Melissa L. Reilly
DOI:10.3987/com-02-s(m)17
日期:——
A synthesis of an advanced seco acid intermediate (7) in a projected total synthesis of kijanolide is described. Key steps in the synthesis of 7 include the highly diastereoselective allylation reaction of 15, the Suzuki cross coupling of dienyl iodide (11) and vinylboronic acid (12), and the IMDA reaction of 9. Elaboration of the spirotetronic acid unit of 7 was accomplished by a Dieckmann cyclization