Journal of the American Chemical Society, Vol.119, No.5, 962-973, 1997
A Unified Total Synthesis of the Immunomodulators (-)-Rapamycin and (-)-27-Demethoxyrapamycin - Assembly of the Common C(1-20) Perimeter and Final Elaboration
The potent, naturally occurring immunomodulators (-)-rapamycin (1) and (-)-27-demethoxyrapamycin (2) have been synthesized via a unified and highly convergent strategy. In the preceding paper we discussed the construction of common building blocks A-C and their linkage to provide the C(21-42) segments of 1 and 2. Herein we describe model studies of triene generation and hydroxyl deprotection, the preparation and coupling of building blocks D and E, a two-step protocol for macrocycle formation via union of the ABC and DE subtargets, and completion of the total syntheses. The synthesis of 27-demethoxyrapamycin (2) confirmed the assigned structure.
Keywords:ALKYNYL ALLYLIC ALCOHOLS;ALPHA-AMINO-ACIDS;C-7 METHOXY GROUP;RAPAMYCIN AY-22;989;ACHIRAL KETONES;EFFECTOR DOMAIN;STILLE REACTION;SIDE-CHAIN;PALLADIUM;CHEMISTRY