Metal-Alkyne and Metallacyclobutene Reactivity toward a Diazoacetamide: Conversion to Highly Functionalized 1,3-Diene Complexes and Oxametallacyclopentadienes

Abstract

Here we report the first reactions of metal-alkyne and metallacyclobutene complexes with a diazoacetamide. Reaction of (η5-C5H5)(PPh3)Co[η2-(R3Si)C≡C(SO2Ar)] (1-TMS, R = Me, Ar = C6H5; 1-TIPS, R = CH(CH3)2, Ar = p-C6H4CH3) and 2-diazo-N,N-dimethylacetamide, N2CH(CONMe2) (7), produces the oxametallacyclopentadiene complexes (η5-C5H5)(SO2Ar)Co[κ2-O═C(NMe2)CC(H)═C(R3Si)] (8-TMS, R = Me, Ar = C6H5; 8-TIPS, R = CH(CH3)2, Ar = p-C6H4CH3). The conversion of 1 and 7 to 8 involves the loss of PPh3, two nitrogen atoms, and a single carbon atom from the starting materials, as well as cleavage of a carbon–sulfur bond and formation of a sulfinato (−SO2Ar) ligand. The cobalt-alkyne complex, (η5-C5H5)(PPh3)Co(η2-PhC≡CPh) (1-Ph), undergoes reaction with 7 to give the cobalt-diene complex (η5-C5H5)Co[η4-(Z,E)-CH(CONMe2)═CPhCPh═CH(CONMe2)] (9-ZE). Treatment of the cobaltacyclobutene, (η5-C5H5)(PPh3)Co[κ2-(3-ethoxycarbonyl)-1-(phenylsulfonyl)-2-(trimethylsilyl)-1-propene-1,3-diyl] (3-TMS), with 7 leads to regio- and diaster...