Modular total synthesis of archazolid A and B.

Institut für Organische Chemie, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, D-69120 Heidelberg.
The Journal of Organic Chemistry (Impact Factor: 4.64). 10/2009; 74(19):7220-9. DOI: 10.1021/jo901565n
Source: PubMed

ABSTRACT A modular total synthesis of the potent V-ATPase inhibitors archazolid A and B is reported. The convergent preparation was accomplished by late-stage diversification of joint intermediates. Key synthetic steps involve asymmetric boron-mediated aldol reactions, two consecutive Still-Gennari olefinations to set the characteristic (Z,Z)-diene system, a Brown crotyboration, and a diastereoselective aldol condensation of highly elaborate intermediates. For macrocyclization, both an HWE reaction and a Heck coupling were successfully employed to close the 24-membered macrolactone. During the synthetic campaign, a generally useful protocol for an E-selective Heck reaction of nonactivated alkenes and a method for the direct nucleophilic displacement of the Abiko-Masamune auxiliary with sterically hindered nucleophiles were developed. The expedient and flexible strategy will enable further SAR studies of the archazolids and more detailed evaluations of target-inhibitor interactions.

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