FORMATION OF NITRILIMINES AND DIAZO-COMPOUNDS FROM LITHIATED AND STANNYL DIAZO DERIVATIVES - SCOPE AND MECHANISM

The lithium salt of [bis(dicyclohexylamino)phosphanyl]diazomethane (7) reacts with bis(diclohexylamino)chlorophosphane (8) leading to a mixture of nitrilimine 9 and diazo derivative 10, in a 21/4 ratio. The reaction of [bis-(diisopropylamino)thioxophosphoranyl] (trimethylstannyl)diazomethane (11) with bis(diisopropylamino)chloroborane (12) gives C-[bis(diisopropylamino)thioxophosphoranyl]-N-[bis(diisopropylamino)boryl]nitrilimine (13), in 60% yield. Bis(trimethylstannyl)diazomethane (14) reacts in polar solvents with 2 equiv of chloroborane 12, chlorophosphanes 1 and 8, triphenylmethyl chloride, and trimethylacetyl chloride affording the corresponding nitrilimines 15, 16, 9, and 17 and oxadiazole 26, respectively, in high yield. In a similar fashion, without solvent, 14 reacts with triisopropylchlorosilane producing nitrilimine 20. In solution, 14 reacts with triisopropylchlorosilane and with acetyl chloride, leading to diazo derivatives 21 and 27 in 55 and 90% yields. Addition of chlorophosphane 1, trimethylacetyl chloride, and methanol to (triisopropylsilyl)(trimethylstannyl)diazomethane (21) gives rise to C-silyl-N-phosphanylnitrilimine 22 (70% yield), oxadiazole 23 (34% yield) and (triisopropylsilyl)diazomethane (24) (95% yield), respectively. It is clear that steric factors control the stability of nitrilimines, as well as the electrophilic C or N attack, and thus the formation of nitrilimines versus diazo derivatives from metalated diazomethane (metal = lithium or tin).