187324-63-6Relevant articles and documents
Modular total synthesis of archazolid A and B
Menche, Dirk,Hassfeld, Jorma,Li, Jun,Mayer, Kerstin,Rudolph, Sven
supporting information; experimental part, p. 7220 - 7229 (2010/02/17)
(Chemical Equation Presented) 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 diastereo-selective 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. 2009 American Chemical Society.
Boron-mediated aldol reaction of carboxylic esters: Complementary anti- and syn-selective asymmetric aldol reactions
Inoue, Tadashi,Liu, Ji-Feng,Buske, Dana C.,Abiko, Atsushi
, p. 5250 - 5256 (2007/10/03)
The boron-mediated aldol reaction of carboxylic esters is described in detail. Contrary to the general belief that carboxylic esters are inert under the condition of the boron enolate formation, propionate esters are enolized with certain combinations of a boron triflate and an amine. More importantly, the stereochemical course of the aldol reaction can be controlled by the judicious selection of the enolization reagents. Treatment of propionate esters with c-Hex2BOTf and triethylamine produces anti-aldol products, and that with Bu2BOTf and diisopropylethylamine gives syn-aldol products selectively after reaction with aldehydes. Complementary anti- and syn-selective asymmetric aldol reactions with structurally related, readily available chiral norephedrine-derived propionate esters are developed.