[1] This effect has been known for many years [2] but in 2005 researchers in the group of K. Barry Sharpless published a systematic study into this phenomenon.
The reaction of quadricyclane with DEAD is a 2σ + 2σ + 2π cycloaddition that on water takes place within 10 minutes at room temperature with 82% yield.
In one study [5] a coupling reaction between an indole and a quinone takes place at room temperature without catalyst in water in 82% chemical yield even though reactants and products are insoluble in this medium.
The on water effect is also studied in cycloadditions of the type:[6] In this reaction the alkyne methyl 2-octynoate reacts with triphenylphosphine to an intermediate zwitterionic allenolate, a dipolarophile for the 1,3-dipole 2-phenylnitrone.
An alternative classification with broader scope is suggested by Yujiro Hayashi [7] as he describes certain organocatalytic Aldol reactions as taking place in the presence of water.