Synthesis of the C10-C25 Northern Moiety of 22,23-Dihydroavermectin B1b
- 1 January 1991
- journal article
- letter
- Published by Georg Thieme Verlag KG in Synlett
- Vol. 1991 (09) , 611-614
- https://doi.org/10.1055/s-1991-20814
Abstract
The C10-C25 spiroacetal moiety of 22,23-dihydroavermectin B1b aglycone has been prepared starting from a previously described optically active C15-C25 sulfone precursor. An asymmetric Hoppe's homoaldol reaction between the intermediate C13-C25 unsaturated aldehyde and enantiomerically enriched titanium (E)-2-butenyl N,N-diisopropylcarbamate, obtained in the presence of (-)-sparteine and tetra(isopropoxy)titanium, generates an anti 12S,13S C10-C25 vinyl carbamate which was transformed into the E-vinylstannane required for the coupling reaction with the C1-C9 part of avermectins.Keywords
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