76123-15-4Relevant academic research and scientific papers
Synthesis of an avermectin-nemadectin hybrid
Shih,Holmes,Mrozik,Fisher
, p. 3663 - 3666 (2007/10/02)
The Wittig condensation of (2R,3R,4E)-2,6-dimethyl-3-trimethylsilyloxy-4- heptenyltriphenylphosphorylidene with aldehyde 1 produced the desired cis olefin 11 in 45% yield. Treatment of this intermediate with pyridinium tosylate in methanol effected spiroketalization and desilylation with hydrogen fluoride-pyridine in THF afforded the avermectin-nemadectin hybrid 2.
The chemistry of cyclic vinyl ethers. 6. Total synthesis of polyether ionophore antibiotics of the calcimycin (A-23187) class
Boeckman Jr., Robert K.,Charette, André B.,Asberom, Theodros,Johnston, Brian H.
, p. 5337 - 5353 (2007/10/02)
An extremely convergent (longest linear sequence, 16 steps), fully stereoselective, and potentially general synthesis of the antibiotic ionophores of the Calcimycin (A-23187) class was devised. The key steps involve a coupling reaction between the chiral nonracemic subunits dihydropyran 41 (as the α-lithio anion) and bromide 49. Subsequent acid-promoted cyclization directly produces the spirocyclic ring system found in the ionophore X-14885A (3). Alternatively, cyclopropanation of substituted vinyl ether 55 followed by acid treatment afforded the spiroketal 58 that was subsequently converted into the polyether ionophore Calcimycin (1) and also Cezomycin (2).
