A TMSOTf-catalyzed Michaelis-Arbuzov reaction of triorganyl phosphites with sterically bulky alcohols

Although more advantageous in several aspects than the reaction of the corresponding halides, the catalytic Michaelis-Arbuzov (MA) reaction of sterically more bulky secondary and tertiary alcohols with triorganyl phosphites is still one of the most challenging tasks that has not been realized so far. Now we have developed a trimethylsilyl triflate (TMSOTf)-catalyzed efficient MA reaction of triorganyl phosphites that can directly employ sterically bulky alcohols as substrates. This new method can be applied to a wide range of primary to tertiary alcohols and also two P(III) esters (phosphonites and phosphinites), providing a general, practical, green and advantageous catalytic MA reaction for the preparation of useful organophosphoryl compounds including phosphonates, phosphinates, and phosphine oxides. Control reactions and density functional theory (DFT) calculations of the reaction revealed that the mechanism of this new MA reaction may be rather complicated: an initial step-wise activation of the substrates to the more reactive intermediates, followed by two different catalytic cycles involving both the S_N1 and S_N2 processes may be involved in the reaction mechanism.