Highly functionalized alkenes produced from base-free organocatalytic Wittig reactions: (<i>E</i>)-3-benzylidenepyrrolidine-2,5-dione, (<i>E</i>)-3-benzylidene-1-methylpyrrolidine-2,5-dione and (<i>E</i>)-3-benzylidene-1-<i>tert</i>-butylpyrrolidine-2,5-dione
M.-L. Schirmer, A. Spannenberg, T. Werner, Acta Crystallographica Section C Structural Chemistry 72 (2016) 504–508.