Progress Towards the Total Synthesis of Trichodermamides A and B:  Construction of the Oxazine Ring Moiety

Abstract

Trichodermamides are modified heterocyclic dipeptides that possess a unique 4H-5,6-dihydro-1,2-oxazine ring. Starting from affordable, easily available (-)-quinic acid, the enantioselective synthesis of this oxazine moiety was achieved by an intramolecular epoxide ring-opening reaction by an oxime. [structure: see text]

Synthesis of α‐Acyloxynitrones and Reactivity towards Samarium Diiodide

“…However, attempts to induce isomerization of oxime Z ‐ 9 failed. Attempted thermal isomerization in protic solvents, photochemical isomerization in dichloromethane or acetonitrile, or treatment of Z ‐ 9 with AlCl 3 in anhydrous dichloromethane all led to decomposition of the starting oxime.…”

Axial Ligand and Spin‐State Influence on the Formation and Reactivity of Hydroperoxo–Iron(III) Porphyrin Complexes

“…The presence of a 4 H ‐5,6‐dihydro‐1,2‐oxazine fragment fused with a highly functionalized cyclohexene ring is a distinguishing structural attribute of these natural products, making them compelling targets for chemical synthesis 4. 5 Owing to the lack of mild methods for the direct assembly of the oxazine rings,6, 7 we recently developed a tandem reaction sequence that integrates nitrosation of ester enolates and a novel Lewis acid mediated hetero‐Cope rearrangement, the oxaza‐Cope rearrangement (Equation (1) in Scheme ), which directly provides bicyclic oxazines from esters 8.…”

Oxazine ring construction: methods and applications to natural product synthesis

“…Treatment of the ketone with hydroxylamine generated the corresponding oxime in situ, which underwent an intramolecular epoxide ring opening upon addition of NaOH to yield oxazine 22 as a single diastereomer. After this preliminary result was published [37], Taylor et al reported a similar methodology Scheme 11 Retrosynthetic analysis of trichodermamides in Joullié's approach.…”