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

Organic Syntheses via Transition Metal Complexes, 62. – First Carbene Complexes (MCr, W) with Carbohydrate Substituents The 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 L n MC(OEt)–CCPh 1 [L n MCr(CO) 5 ( a ), W(CO) 5 ( b )] to give vinylcarbene complexes L n MC(OEt)–CHC(Ph)–O(sugar) ( E/Z )‐ 3a–g in good to excellent yields. As a minor side reaction the alkynyl carbene complex (CO) 5 WC(OEt)–CCPh ( 1b ) isomerises to give the 1,2–propadienylidene complex (CO) 5 WCCC(OEt)C 6 H 5 ( 4b ).