TY - JOUR A1 - Schmidt, Bernd A1 - Geissler, Diana T1 - Olefin-Metathesis-Based Synthesis of Furans by an RCM/Deprotonation/Phosphorylation Sequence and Their Diels-Alder Reactions JF - European journal of organic chemistry N2 - Butenolides, obtained by ring-closing metathesis (RCM) of acrylates, undergo quantitative deprotonation with amide bases. Trapping of the resulting anions with electrophiles, for example, chlorophosphates, give furans. Subsequent DielsAlder reaction and acid-catalysed rearrangement of the resulting oxabicyclonorbornadienes give substituted benzenes. KW - Lactones KW - Metathesis KW - Ruthenium KW - Oxygen heterocycles KW - Metalation Y1 - 2011 U6 - https://doi.org/10.1002/ejoc.201101078 SN - 1434-193X IS - 35 SP - 7140 EP - 7147 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schmidt, Bernd A1 - Staude, Lucia A1 - Kelling, Alexandra A1 - Schilde, Uwe T1 - A Cross-Metathesis-Conjugate addition route to enantiopure gamma-Butyrolactams and gamma-Lactones from a C-2-Symmetric Precursor JF - European journal of organic chemistry N2 - A protected derivative of (3R, 4R)-hexa-1,5-diene-3,4-diol, a conveniently accessible C-2-symmetric building block, undergoes single or double cross metathesis with methyl acryl-ate. The cross metathesis products are amenable to stereoselective conjugate addition reactions and can be converted into either gamma-butyrolactones or gamma-lactams. KW - Lactams KW - Lactones KW - Oxygen heterocycles KW - Metathesis KW - Desymmetrization Y1 - 2011 U6 - https://doi.org/10.1002/ejoc.201001528 SN - 1434-193X IS - 9 SP - 1721 EP - 1727 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Schmidt, Bernd A1 - Kunz, Oliver T1 - One-Flask tethered ring closing Metathesis-Electrocyclic ring opening for the highly stereoselective synthesis of conjugated Z/E-Dienes JF - European journal of organic chemistry N2 - A one-flask reaction sequence comprising ring closing metathesis (RCM) of butenoates derived from allylic alcohols and a base-mediated ring opening gives 2Z,4E-configured dienoic acids in high yields and stereoselectivities. Application of the method to the synthesis of the natural product fusanolide A suggests that the originally published structure was erroneously assigned and should be revised. KW - Natural products KW - Lactones KW - Macrocycles KW - Metathesis KW - Carboxylic -acids Y1 - 2012 U6 - https://doi.org/10.1002/ejoc.201101497 SN - 1434-193X IS - 5 SP - 1008 EP - 1018 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schmidt, Bernd A1 - Hauke, Sylvia T1 - Metathesis-Based de novo synthesis of noviose JF - European journal of organic chemistry N2 - The rare carbohydrate L-(+)-noviose was synthesized from enantiomerically pure L-lactate. The configuration at C-4 was established by diastereoselective nucleophilic addition to an in-situ-generated lactaldehyde. The resulting homoallylic alcohol was further transformed into a set of ring-closing metathesis (RCM) precursors. These compounds were converted into noviose in few steps using RCM and RCM-allylic-oxidation sequences. KW - Carbohydrates KW - Allylic oxidation KW - Oxygen heterocycles KW - Metathesis KW - Ruthenium Y1 - 2014 U6 - https://doi.org/10.1002/ejoc.201301615 SN - 1434-193X SN - 1099-0690 VL - 2014 IS - 9 SP - 1951 EP - 1960 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Lood, Kajsa A1 - Tikk, Triin A1 - Krüger, Mandy A1 - Schmidt, Bernd T1 - Methylene capping facilitates cross-metathesis reactions of enals BT - a short synthesis of 7-methoxywutaifuranal from the xylochemical isoeugenol JF - The journal of organic chemistry N2 - 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. KW - Aldehydes KW - Catalysts KW - Hydrocarbons KW - Metathesis KW - Mixtures Y1 - 2022 U6 - https://doi.org/10.1021/acs.joc.1c02851 SN - 0022-3263 SN - 1520-6904 VL - 87 IS - 5 SP - 3079 EP - 3088 PB - American Chemical Society CY - Washington ER -