Strategies and Tactics for the Synthesis of Oxygenated Natural Products

Abstract

The total synthesis of the ansa antibiotic macbecin I [1] is described exploiting an approach that features the oxidative transformation of furans into hydropyrans that then serve as conformationally biased templates for stereoselective refunctionalization and elaboration. A novel variant of the Mitsunobu reaction was developed that may be applied to the inversion of hindered secondary alcohols. In work directed toward the total synthesis of the antifungal antibiotic ambruticin [3], new and general methods have been invented for the asymmetric synthesis of functionalized cyclopropanes by intramolecular cyclopropanations of omega-unsaturated diazoacetates and the convergent stereoselective synthesis of trisubstituted alkenes.

TEMPO in Chemical Transformations: From Homogeneous to Heterogeneous

“…N -Alkoxyamines, derived from persistent sterically hindered aminoxyl radicals, represent an important and rapidly growing class of organic compounds in natural product synthesis and pharmaceutical agents . These alkoxyamines can also be used for controlled radical polymerization, as polymer light stabilizers, peroxide substitutes (rheology modifiers) or fireproofing agents .…”

A general approach to the enantioselective α-oxidation of aldehydesvia synergistic catalysis

“…Found among many natural and non-natural medicinal agents, oxygen-bearing stereocenters are a fundamental structural motif that is broadly represented throughout the realm of organic architecture. [1][2][3] While traditional synthetic approaches to enantioselective C-O bond formation are strikingly powerful (olefin epoxidation/dihydroxylation, ketone reduction), new strategies continue to expand the range of starting materials or functional groups from which this important stereogenicity can be created. Recently, the enantioselective a-oxidation of aldehydes has garnered substantial attention as a novel catalytic approach to asymmetric oxygen-bearing stereocenters.…”