135419-88-4Relevant articles and documents
Total Synthesis of the Anthelmintic Macrolide Avermectin B1a
Ley, Steven V.,Armstrong, Alan,Diez-Martin, David,Ford, Mark J.,Grice, Peter,et al.
, p. 667 - 692 (2007/10/02)
A highly convergent total synthesis of the anthelmintic macrolide avermectin B1a is described.The key features of this synthesis include the introduction of the C(11)-C(15) portion by selective ring opening of a symmetrical 1,4-bis-epoxide 4 followed by reaction with the anion derived from the 3-methyl-2-(1-methylpropyl)-6-phenylsulphonylpyran 3 to afford the 'northern' C(11)-C(25) fragment 39.Coupling of the derived C(11)-C(25) aldehyde unit 42 with a C(1)-C(10) 'southern' fragment 2 was achieved via a novel deconjugative vinyl sulphone anion sequence.Macrolactonisation and subsequent introduction of the 3,4-double bond gave the aglycone portion 51.The oleandrosyloleandrose disaccharide was introduced by a novel silver-mediated coupling between the 5-acetylated aglycone 70 and the thiocarbonylimidazolide 69.Final deacetylation was accomplished using Super-Hydride to give the natural product 1.
