Asymmetric Synthesis of Calyculin C. 2. Synthesis of the C(26)-C(37) Fragment and Model Wittig Couplings.
We report our synthesis of the C(26)-C(37) fragment of serine/threonine protein phosphatase PP1 and PP2A inhibitor calyculin C (1). Outlined in this paper are synthetic approaches to the two components based on disconnection at the C(33)-N(3) amide bond. We report the successful synthesis of the C(33)-C(37) aza-sugar derived from D-lyxose which was coupled onto a C(26)-C(32) aminooxazole originating from L-pyroglutamic acid. Elaboration of the resulting amide to a fully deprotected C(26)-C(37) fragment of calyculin C completed our synthesis. This provided an appropriate phosphonium salt for use in a Wittig olefination for joining both halves of the natural product.
Ogawa
Anthony K.
AK
Department of Chemistry and Biochemistry, University of California, Los Angeles, 90095.
DeMattei
John A.
JA
Scarlato
Gerard R.
GR
Tellew
John E.
JE
Chong
Lee S.
LS
Armstrong
Robert W.
RW