摘要：

Theannuloselectivitydefinedastheannulationselectivitybetween[2+2]andcascadeannulationsofdiacyldichloridesandiminesinthepresenceoforganicbasestoaffordbis-β-lactamsand2,3-dihydro-1,3-oxazin-4-oneshasbeenstudiedextensivelywithacombinationofexperimentsanddensityfunctionaltheory(DFT)calculationsThepresentresultsindicatethatitisthepreferenceofdiacyldichloridesintheformationofcyclicα-oxoketenesinthepresenceoforganicbasesthatcontrolstheannuloselectivityThecascadeannulationsofhexanedioylandheptanedioyldichloridesundergothechloride-assistedcyclizationofthecorrespondingω-chlorocarbonylalkylketenesastherate-determiningstepinthepresenceoftriethylamine,ratherthanthegenerationofbisketenesfollowedbydimerization,affordingfive-andsix-memberedcyclicα-oxoketenesfollowedbythe[4+2]annulationswithiminestofurnish2,3-dihydro-1,3-oxazin-4-onesThisisanenergeticallycompetitivepathwaytothenormalStaudingercycloadditionFurtherdecreasing(pentanedioyldichloride)orincreasingthelinkerlength(octanedioylandnonanedioyldichlorides)resultsintheenhancedenergeticbarriersforthecyclization,whichislesscompetitivetothedirectStaudingercycloadditiontoaffordbis-trans-β-lactamsasthesoleproductsThecurrentresultsprovideaninsightintotheannuloselectivecontrolinthereactionsofdiacyldichloridesandimines

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