Configuration and E / Z interconversion mechanism of O ( S )‐allyl‐ S ( O )‐methyl‐ N ‐(acridin‐9‐yl) iminothiocarbonate

The configuration and dynamic behavior of O ‐allyl‐ S ‐methyl‐ N ‐(acridin‐9‐yl)iminothiocarbonate ( 1 ) and its S ‐allyl‐ O ‐methyl regioisomer ( 2 ) were studied using quantum chemical calculations and by applying a novel graphical method to scatter maps obtained from MD simulations for evaluation of an NOE‐weighted internuclear distance ( r NOE ). Energy calculations indicated that the Z configuration was predominant for each compound and, further, this was supported both by the calculated chemical shifts and the r NOE . Both N‐inversion‐ and rotation‐type transition‐state structures were also calculated for the E / Z isomerization process, the results indicating that the preferred interconversion mechanism for 1 is N‐inversion, but contrastingly, interconversion via rotation is equally as probable as N‐inversion for 2 . This supports the notion that one or the other or both pathways can be active and each system needs to be assessed on a case‐by‐case basis. Copyright © 2005 John Wiley & Sons, Ltd.