Amino acid derived 3-pyrrolines can be readily prepared in a single step in enantiomerically pure form by cycloalkylation of the corresponding amino esters with (Z)-1,4-dichloro-2-butene. Enantiopure azabicyclo[3.3.0]octenones can be then easily obtained through an unprecedented Pauson-Khand reaction followed by diastereomer separation.
![Pauson-Khand reaction of amino acid derived 3-pyrrolines: New enantiopure scaffolds for diversity-oriented synthesis](https://www.iciq.org/wp-content/uploads/2014/03/Pauson-Khand-reaction_eng_noticies_articles_2007_28.gif)