Pyrolysis of variously pretreated or untreated samples of chitin (1) and certain congeners at 150−350 °C afforded a range of platform molecules, as exemplified by compounds 4, 5, 6, 8, 12 and 13. All of these products have been fully characterized, including by single-crystal X-ray analysis. Pathways for the formation of them are proposed and theoretical studies of certain aspects of these described.
The synthesis of the structure, 1, assigned to the anti-inflammatory natural product myrsinoic acid F is reported together with a means for preparing its Z-isomer 21. While neither of these compounds corresponds to the natural product, both of them are anti-inflammatory agents (as determined using a mouse ear edema assay) with congener 1 being notably more potent than the widely prescribed NSAID indometacin.
α,β-Unsaturated aldehydes 6a-j undergo an enantioselective allylation with allylic trichlorosilanes 2a,b in the presence of METHOX (4) as a Lewis basic catalyst (≤10 mol %) to produce the homoallylic alcohols 7a-l at good to high enantioselectivity (83-96% ee). This study shows that the reactivity scope of METHOX can be extended from aromatic to nonaromatic aldehydes.
Enantioselective synthesis of all-carbon quaternary centers remains a considerable challenge for synthetic organic chemists. Here, we report a two-step protocol to synthesize such centers including tandem cyclization/Suzuki cross-coupling followed by halocarbocyclization. During this process, two rings, three new C-C bonds and a stereochemically defined all-carbon quaternary center are formed. The absolute configuration of this center is controlled by the stereochemistry of the adjacent stereocenter, which derives from an appropriate enantioenriched starting material. Using this method, we synthesized polycyclic compounds structurally similar to Amaryllidaceae alkaloids in high enantiomeric excesses. Because these products resemble naturally occurring compounds, our protocol can be used to synthesize various potentially bioactive compounds.
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