NC?. 2 157 tetrakis (trimethylsily1) esters under exceedingly mild conditions, typically 1-2 hr at 25". Specific examples comparing alkyl phosphonate silylations with (4a) and (4b) are presented in Table I. In a representative experiment, l-2 mnol of the neat phosphonate alkyl ester in an N2-filled, thermostatted nmr tube equipped with a septum stopper was treated with the indicated amount of (4b), injected with the aid of a plastic syringe. After mixing, the ...