Total synthesis of the deshydroxyajudazols A and B

Abstract

The asymmetric total synthesis of the proposed structures for the deshydroxyajudazols A (28) and B (29) is described. The C9-C10 stereochemistry was installed using a Brown asymmetric crotylmetallation reaction with (-)-(Ipc)2BOMe and trans-2-butene, whilst the isochromanone ring system was generated by an intramolecular Diels-Alder reaction of bromide 103 followed by DDQ oxidation. Br-OH exchange using a Pd catalysed cross coupling between pinacolborane and bromide 103 followed by oxidation and hydrolysis of the resulting boronate furnished phenol 180. The installation of the oxazole began with a one carbon extension of 229 before dihydroxylation of the resulting alkene to give diol 235. Fu..