40662-79-1Relevant academic research and scientific papers
Synthesis of Ynolates via Double Deprotonation of Nonbrominated Esters
Sun, Jun,Yoshiiwa, Toshiya,Iwata, Takayuki,Shindo, Mitsuru
supporting information, p. 6585 - 6588 (2019/09/30)
Herein, we report a double deprotonation method used for the preparation of ynolates starting from nonbrominated 2,6-di-tert-butylphenyl esters. The current method is superior to the previously described double lithium/halogen exchange approach because easily accessible starting materials are used. This method will be especially useful for preparation of ynolates bearing functional groups in organic synthesis.
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
