THE TOTAL SYNTHESIS OF SCYTOPHYCIN-C - PART 1 - STEREOCONTROLLED SYNTHESIS OF THE C-1-C-32 PROTECTED SECO ACID

A stereocontrolled synthesis of the C-1-C-32 seco acid derivative 9 fo r scytophycin C (1) was completed in 14 steps (18.2% yield, 85% ds) fr om aldehyde(S)-18. Key steps include: (i) the asymmetric crotylboratio n of (S)-18 to give homoallylic alcohol 15; (ii) the boron-mediated al dol construction of aldehyde 14 from (S)-17; (iii) the Ba(OH)(2)-promo ted HWE reaction, 13 + 14 --> 31; (iv) the highly stereocontrolled Muk aiyama aldol coupling between silyl enol ether 33 and aldehyde 11 to g ive adduct 10; (v) the chemoselective reduction at C-17 of ketone 10 t o produce 1,3-syn-diol 34. (C) 1998 Elsevier Science Ltd. All rights r eserved.