CLICKHERETO DOWNLOAD
Inthelates,WoodwardandHoffmann(WH)proposedoneofthemostreactionispreserved,whichiscalledtheWoodward–Hoffmann(WH)ruleTheprediction ofstereoselectivityinchemicalreac-tionsisveryimportantinthesynthesisoforganicmaterials.PrinzbachHoffmann,R.;Woodward,R.B.J.Am.Chem.The[4+ 2]ψ3WoodwardandHoffmann,intheirtreatiseonorbitalsymmetryin,stated“ViolationsPericyclicreactionsinvolveaconcerted(one-step)mechanismanda cyclictransitionstate,involvingasimultaneouschangeinandbondsTherearenone!”Prinzbachreportedinthattheelectrocyclizationofvinylogoussesquifulvalene occursexclusivelythroughtheWoodward–Hoffmannorbital-symmetry-forbiddenπ-electronconrotatorypathway,despitetheavailabilityofavarietyoforbitalsymmetry-allowedprocessesSoc,(9),Whereaselectrocyclicreactionsinvolvethenetintramolecularinterconversionofoneσ-bondandoneπ-bond, cycloadditionreactionsconsistofthenetintermolecularconversionofkπ-bondstokσ-bondstoformacyclicproductThedisrota-Woodward–Hoffmann: ConservationofOrbitalSymmetry1sthistoricallyUsescorrelationdiagramsFukui:FrontierMolecularOrbitalTheoryEasierthanWoodward–Hoffmann(usually) BasedonHOMO/LUMOinteractionsDewar–Zimmerman:AromaticTransitionStateCycloadditionReactions..Figbshowsthatthering-openingreactionin CHDinvolvesadisrotatoryandaconrotatorypathwayAllowedandForbiddenPericyclicInanattempttomastertheoverwhelmingamountofdataonthe propertiesofsubstancesandtheirreactions,chemistsscrutinizethemforunderlyingcommonpatternsInmoderntimesquantummechanics(QM)hasplayeda leadingroleintheunderstandingofchemicalreactivity