Über die stereoselektive Bildung von syn‐ und anti‐Dicarbonyl(1‐methyl‐η3‐2‐propenyl)nitrosyleisen und die Struktur von syn‐Carbonyl(1‐methyl‐η3‐2‐propenyl)nitrosyl(triphenylphosphan)eisen

On the Stereoselective Formation of syn‐ and anti‐Dicarbonyl‐(1‐methyl‐η3‐2‐propenyl)nitrosyliron and the Structure of syn‐Carbonyl(1‐methyl‐η3‐2‐propenyl)nitrosyl(triphenylphosphine)iron The reactions of MFe(CO)3NO (7, M = K) with (E)‐ and (Z)‐2‐butenyl mesylate (E‐1 and Z‐1; R = CH3, X = OSO2CH3) lead stereoselectively to syn‐ and anti‐dicarbonyl(1‐methyl‐η3‐2‐propenyl)nitrosyliron (syn‐6 and anti‐6), respectively. In a subsequent selective reaction with the anion of dimethyl malonate, these complexes afford [along with dimethyl (1‐methyl‐2‐propenyl)malonate (4; R = CH3 Nu = CH(CO2CH3)2)] dimethyl (E)‐ and (Z)‐ 2‐butenylmalonate [E‐3 and Z‐3; R = CH3, Nu = CH(CO2‐CH3)2], where the double‐bond geometries of the educts are retained. Upon treatment with PPh3 (11), both, syn‐6 and anti‐6 (latter with isomerization), form the same crystalline complex, syn‐carbonyl(1‐methyl‐η3‐2‐propenyl)nitrosyl(triphenylphosphine)‐ iron (12); its structure was determined by X‐ray diffraction.