Synthetic studies on azadirachtin (Part 3): Asymmetric synthesis of the tricyclic dihydrofuran moiety of azadirachtin

C2-Symmetric Chiral Bis(Oxazoline) Ligands in Asymmetric Catalysis

“…The next paragraphs are the summary of the story, and Table 46 starts to summarize the results obtained within these years, investigating the reaction between 3-acryloyl-2-oxazolidinone and cyclopentadiene with different catalysts (changing the cations and their counterions with phenyl-and tert-butyl-box's), different solvents, and the effects of several additives that sometimes have a dramatic effect on enantioselectivity. From the investigations by Evans et al, it appears that the best combination is box 2 and Cu(II) 46,60,120,214,215,222 and the best counterions are OTf and SbF 6 (Table 46, entries 3-8). Among the tests with different cations (Table 46, entries 9-16), only cobalt and manganese gave discrete enantiomeric excesses, by far not comparable to copper.…”

Syntheses, Antifeedant Activity, and QSAR Analysis of New Oxa(thia)diazolyl 3(2H)-Pyridazinones

“…There has been much interest recently in natural products that exhibit antifeedant activity from an agricultural point of view ( , ). The best known example is azadirachtin, a potent antifeedant and insect growth regulator isolated from the seed of the Indian neem tree ( , ). However, their translation into a commercial product has been slow, partly because of the structural complexity, instability, and synthetic inaccessibility of those natural products.…”

The Azadirachtin Story

“…Murai et al. have also reported studies towards the total synthesis of azadirachtin in which hydroxyfuran acetal 106 was prepared as a key building block (Scheme ) 57…”