Organische Synthesen mit Übergangsmetall–Komplexen, 62. Erste Carbenkomplexe (MCr, W) mit Kohlenhydrat–Substituenten

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Organic Syntheses via Transition Metal Complexes, 62. – First Carbene Complexes (MCr, W) with Carbohydrate SubstituentsThe first examples of transition metal carbene complexes of carbohydrate derivatives are described: 1,2:5,6–Di‐O‐isopropyliden‐α‐D–glucofuranose (2a), 1,2:5,6–di‐O‐isopropylidene‐α‐D–allofuranose (2b), and 2,3:5,6–di‐O‐isopropyliden‐α‐D–mannofuranose (2c) add regiospecifically at C–3 of alkynylcarbene complexes LnMC(OEt)–CCPh 1 [LnMCr(CO)5 (a), W(CO)5 (b)] to give vinylcarbene complexes LnMC(OEt)–CHC(Ph)–O(sugar) (E/Z)‐3a–g in good to excellent yields. As a minor side reaction the alkynyl carbene complex (CO)5WC(OEt)–CCPh (1b) isomerises to give the 1,2–propadienylidene complex (CO)5WCCC(OEt)C6H5 (4b).