Illustration for the <a href="https://en.wikipedia.org/wiki/captodative_effect" class="extiw" title="en:captodative effect">en:captodative effect</a> page of the [2+2] cyclodimerisation of 2-methylthioacrylonitrile and an intramolecular [2+2] cycloaddition involving captodative radical intermediates, adapted from <cite class="book" style="font-style:normal">"Captodative Substituent Effects in Cycloaddition Reactions" in   (1986) <i> <a rel="nofollow" class="external text" href="https://books.google.com.au/books?id=T1fi2zcEQsMC&amp;pg=PA362&amp;dq=captodative+ethylene&amp;hl=en&amp;sa=X&amp;ei=uN22UreyPIejlQX_wYCQDw&amp;ved=0CC4Q6AEwAA#v=onepage&amp;q=captodative%20ethylene&amp;f=false">Substituent Effects in Radical Chemistry</a></i>, Springer, pp. 361−370  <small><a href="https://en.wikipedia.org/wiki/International_Standard_Book_Number" class="extiw" title="en:International Standard Book Number">ISBN</a>:  <a href="//commons.wikimedia.org/wiki/Special:BookSources/9789027723406" title="Special:BookSources/9789027723406">9789027723406</a>. </small></cite>.
<b><a href="//commons.wikimedia.org/wiki/User:Ronhjones" title="User:Ronhjones"><span style="border:1px solid;color:#dfdfdf; padding:1px;background:#ffffdf"><font color="green"> Ron<font color="red">h</font>jones </font></span></a></b><sup><a href="//commons.wikimedia.org/wiki/User_talk:Ronhjones" title="User talk:Ronhjones"> (Talk)</a></sup>
SVG version of <a href="https://en.wikipedia.org/wiki/File:2plus2_cyclodimerisation_and_intramolecular_cyclisation_of_captodative_olefins.jpg" class="extiw" title="en:File:2plus2 cyclodimerisation and intramolecular cyclisation of captodative olefins.jpg">en:File:2plus2 cyclodimerisation and intramolecular cyclisation of captodative olefins.jpg</a> by <a href="https://en.wikipedia.org/wiki/User:EdChem" class="extiw" title="en:User:EdChem">en:User:EdChem</a>