Total Synthesis of (−)-Geissoschizol through Ir-Catalyzed Allylic Amidation as the Key Step: OL 2017

Total Synthesis of (−)-Geissoschizol through Ir-Catalyzed Allylic Amidation as the Key Step

The iridium-catalyzed, Zn(OTf)2 promoted asymmetric allylic amidation of a secondary alcohol derived from tryptamine has been utilized to forge a tetrahydro-β-carboline. Based on this key step, a novel, facile, and enantioselective total synthesis of (−)-geissoschizol was achieved in 10 steps.

More Information: http://pubs.acs.org/doi/10.1021/acs.orglett.7b03133

Total Synthesis of Lycoricidine and Narciclasine by Chemical Dearomatization of Bromobenzene: ACIE 2017

Total Synthesis of Lycoricidine and Narciclasine by Chemical Dearomatization of Bromobenzene




The total synthesis of lycoricidine and narciclasine is enabled by an arenophile-mediated dearomative dihydroxylation of bromobenzene. Subsequent transpositive Suzuki coupling and cycloreversion deliver a key biaryl dihydrodiol intermediate, which is rapidly converted into lycoricidine through site-selective syn-1,4-hydroxyamination and deprotection. The total synthesis of narciclasine is accomplished by the late-stage, amide-directed C−H hydroxylation of a lycoricidine intermediate. Moreover, the general applicability of this strategy to access dihydroxylated biphenyls is demonstrated with several examples.

Total synthesis of (+)-blennolide C and (+)-gonytolide C via spirochromanone: Tetrahydron Letters 2017

Total synthesis of (+)-blennolide C and (+)-gonytolide C via spirochromanone

We report the asymmetric total synthesis of (+)-blennolide C and (+)-gonytolide C isolated from endophytic fungi. The synthesis involved construction of a spirochromanone with a chiral quaternary carbon by the aldol reaction of o-hydroxyacetophenones and optically active α-oxygenated cyclohexenone, followed by cyclization under acidic conditions. Oxidative cleavage of the alkene moiety of the spirochromanone furnished the chromanone diester. Through treating the diester with a Lewis acid, the first total synthesis of (+)-blennolide C was achieved by deprotecting the oxygen functionality of the diester and simultaneous Dieckmann condensation. Total synthesis of (+)-gonytolide C was also achieved by lactone formation from the deprotected diester.

Total Synthesis and Anti-inflammatory Evaluation of Penchinone A and Its Structural Analogues: JOC 2017

Total Synthesis and Anti-inflammatory Evaluation of Penchinone A and Its Structural Analogues

The first total synthesis and biological evaluation of penchinone A and its structural analogues are described. The key steps for the preparation of penchinone A derivatives involve the oxime-directed palladium(II)-catalyzed oxidative acylation, Claisen rearrangement, and base-mediated olefin migration. This transformation efficiently provides a range of allyl-substituted biaryl ketones with site-selectivity and functional group compatibility. In addition, all synthetic compounds were screened for anti-inflammatory activity against nitric oxide (NO), tumor necrosis factor alpha (TNF-α), and interleukin-6 (IL-6) with lipopolysaccharide (LPS)-induced RAW264.7 cells. Generally, a range of penchinone A derivatives potently inhibited NO, TNF-α, and IL-6 productions, compared to dexamethasone as a positive control. Notably, penchinone A (8g) and its derivatives (8e and 8f) were found to exhibit anti-inflammatory activity stronger than that of dexamethasone.