171234-22-3Relevant academic research and scientific papers
Total synthesis of avermectins Part 2: Enantioselective synthesis of the C10-C25 northern fragment and final steps for the construction of the 22,23-dihydroavermectin B1b aglycone
Ferezou, Jean-Pierre,Julia, Marc,Li, Yun,Liu Lu Wei,Pancrazi, Ange
, p. 428 - 452 (2007/10/02)
The total synthesis of the aglycone of 22,23-dihydroavermectin B1b involves a retrosynthetic two building-blocks approach.A Stille Pd(0) catalyzed cross-coupling reaction is carried out between a northern C10-C25 E-vinylstannane and a southern C1-C9 vinyl iodide.The final steps include successive removal of the carboxyl β-(trimethylsilyl)ethyl protecting group of the intermediate secoester, macrolactonization under Yonemitsu's conditions and removal of the 5-O-TBS protecting group.These last steps have been carried out with the aid of a relay study from commercial Ivermectin; a macrolactone opening reaction of the aglycone in the presence of Ti(OiPr)4 has been developed where the crucial Δ3,4 double bond as well as the configuration at C-2 were totally preserved. - Key words: avermectin / spiroketal / diastereoselection / aldolization / sulfone / homoaldolization / Hoppe reaction / hydrostannylation / palladium Stille coupling / titanium isopropoxide / transesterification / macrolactone / total synthesis
ENANTIOSELECTIVE SYNTHESIS OF THE SPIROKETAL UNIT OF MILBEMYCINS AND 22,23-DIHYDROAVERMECTINS
Ferezou, J. P.,Gauchet-Prunet, J.,Julia, M.,Pancrazi, A.
, p. 3667 - 3670 (2007/10/02)
The crystalline spiroketal sub-unit 9 has been synthesized in ten steps from the 2S,3R-diol 2 using a remote partial stereocontrol for the aldolisolation step.
