Preparation and reactivity of mixed benzylic 1,1-dimetalloalkanes

Article abstract of DOI:10.1021/om00114a016

The carbometalation of (α-styryl)magnesium or -lithium organometallics with various allylic zinc bromides allows a general preparation of mixed benzylic 1,1-dimetalloalkanes in good to excellent yields. Their low reactivity can be increased by a transmetalation with copper cyanide leading to copper, zinc dimetallic reagents which are readily bis-allylated with allyl bromide or bis-stannylated with trimethyltin chloride. Transmetalation with 1 equiv of trimethyltin chloride in the absence of copper salts affords tin, zinc 1,1-dimetallo derivatives that can be cleanly oxidized by air to aromatic ketones under very mild conditions (-10 to 0°C, 0.5-4 h). The monolithiation of the bis(trimethylstannyl) derivative 7 provides the α-lithiated benzylic tin compound 8 whose reactivity is also described.