5.

(A) Experimental investigation of the influence of water removal on the catalytic Mitsunobu reaction performed between (R/S)-1-phenylpropan-2-ol and 2,4-dinitrobenzoic acid with 1a (20 mol %) in toluene at 111 °C with two drying techniques: Dean–Stark or overhead desiccant (3 Å molecular sieves suspended above the refluxing reaction, see Supporting Information, Section S6.1 for experimental details). (B) Reaction parameters determined for the two drying techniques (error bars given as a single standard deviation based on three repeats, see Supporting Information, Section S6.1 for details). (i) The conversion to product after 20 h. (ii) The final water content of the reaction after 20 h as determined by Karl–Fischer titration. (iii) The rate of water removal as determined from fitting the kinetic model to experimentally determined data (see Supporting Information, Section S6.2, error bars given as a standard 10% error).