A highly atom economic, chemo-, regio- and stereoselective synthesis and crystal structure of novel spiro-cyclopentanone

The 1,3-dipolar cycloaddition of azomethine ylides derived from acenaphthenequinone and alpha-amino acid (sarcosine) to a series of 2,5-bis(fluorobenzylidene) cyclopentanones afforded novel spiro-cyclopentanone-pyrrolizines chemo-, regio- and stereoselectively in quantitative yields (95-96 %). The crystal structure of one compound containing bis(2,6-difluorobenzyl) (2b) is described. The cyclopentane rings in bis(2,6-difluorobenzyl) (2b) have an envelope conformation.