@article{LoodTikkKruegeretal.2022,
  author    = {Lood, Kajsa and Tikk, Triin and Kr{\"u}ger, Mandy and Schmidt, Bernd},
  title     = {Methylene capping facilitates cross-metathesis reactions of enals},
  series = {The journal of organic chemistry},
  volume    = {87},
  journal   = {The journal of organic chemistry},
  number    = {5},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0022-3263},
  doi       = {10.1021/acs.joc.1c02851},
  pages     = {3079 -- 3088},
  year      = {2022},
  abstract  = {Four combinations of type-I olefins isoeugenol and 4-hydroxy-3-methoxystyrene with type-II olefins acrolein and crotonaldehyde were investigated in cross-metathesis (CM) reactions. While both type-I olefins are suitable CM partners for this transformation, we observed synthetically useful conversions only with type-II olefin crotonaldehyde. For economic reasons, isoeugenol, a cheap xylochemical available from renewable lignocellulose or from clove oil, is the preferred type-I CM partner. Nearly quantitative conversions to coniferyl aldehyde by the CM reaction of isoeugenol and crotonaldehyde can be obtained at ambient temperature without a solvent or at high substrate concentrations of 2 mol.L-1 with the second-generation Hoveyda-Grubbs catalyst. Under these conditions, the ratio of reactants can be reduced to 1:1.5 and catalyst loadings as low as 0.25 mol \% are possible. The high reactivity of the isoeugenol/crotonaldehyde combination in olefin metathesis reactions was demonstrated by a short synthesis of the natural product 7-methoxywutaifuranal, which was obtained from isoeugenol in a 44\% yield over five steps. We suggest that the superior performance of crotonaldehyde in the CM reactions investigated can be rationalized by "methylene capping", i.e., the steric stabilization of the propagating Ru-alkylidene species.},
  language  = {en}
}
@article{NchiozemNgnitedemSperlichMatietaetal.2023,
  author    = {Nchiozem-Ngnitedem, Vaderament-Alexe and Sperlich, Eric and Matieta, Valaire Yemene and Kuete, Jenifer Reine Ngnouzouba and Kuete, Victor and Omer, Ejlal A. A. and Efferth, Thomas and Schmidt, Bernd},
  title     = {Synthesis and bioactivity of isoflavones from ficus carica and some non-natural analogues},
  series = {Journal of natural products : Lloydia},
  volume    = {86},
  journal   = {Journal of natural products : Lloydia},
  number    = {6},
  publisher = {American Chemical Society},
  address   = {Washington, DC},
  issn      = {0163-3864},
  doi       = {10.1021/acs.jnatprod.3c00219},
  pages     = {1520 -- 1528},
  year      = {2023},
  abstract  = {FicucariconeD (1) and its 4 '-demethyl congener 2 are isoflavones isolated from fruits of Ficus carica that share a 5,7-dimethoxy-6-prenyl-substituted A-ring. Both naturalproducts were, for the first time, obtained by chemical synthesisin six steps, starting from 2,4,6-trihydroxyacetophenone. Key stepsare a microwave-promoted tandem sequence of Claisen- and Cope-rearrangementsto install the 6-prenyl substituent and a Suzuki-Miyaura crosscoupling for installing the B-ring. By using various boronic acids,non-natural analogues become conveniently available. All compoundswere tested for cytotoxicity against drug-sensitive and drug-resistanthuman leukemia cell lines, but were found to be inactive. The compoundswere also tested for antimicrobial activities against a panel of eightGram-negative and two Gram-positive bacterial strains. Addition ofthe efflux pump inhibitor phenylalanine-arginine-beta-naphthylamide(PA beta N) significantly improved the antibiotic activity in mostcases, with MIC values as low as 2.5 mu M and activity improvementfactors as high as 128-fold.},
  language  = {en}
}