资源描述：
《Non-aqueous iminium salt mediated catalytic asymmetric》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。
1、Tetrahedron62(2006)66076613Non-aqueousiminiumsaltmediatedcatalyticasymmetricepoxidationPhilipC.BulmanPage,a,*BenjaminR.Buckley,aDavidBarros,aA.JohnBlacker,baaHarryHeaneyandBrianA.MarplesaDepartmentofChemistry,LoughboroughUniversity,Loughborough,LeicestershireLE113TU,UKbNPILPharmaceuticals(UK
2、)Ltd.,POBox521,LeedsRoad,Huddersfield,HD21GA,UKReceived26August2005;revised13October2005;accepted13October2005Availableonline5June2006AbstractArangeofsubstituteddihydroisoquinoliniumsaltshasbeentestedinthecatalyticasymmetricepoxidationofsimplealkenesusingournewlydevelopednon-aqueousconditions
3、employingtetraphenylphosphoniummonoperoxysulfate(TPPP)asoxidant,givingeesofupto97%.Ó2006ElsevierLtd.Allrightsreserved.1.Introductiontheuseofoxoneasstoichiometricoxidant,abase(2molequivofNa2CO3perequivofoxone)andwater/acetonitrileIn1976,itwasestablishedthatoxaziridiniumsaltsareex-assolventmix
4、ture.tremelyreactivereagentsforoxygentransfertonucleophilicsubstrates.1Sincethen,therehasbeensignificantinterestinTheprincipallimitationofthissystemistherestrictedrangedevelopingeffectiveiminiumsaltcatalystsforepoxidationoftemperaturesatwhichtheepoxidationcanbeperformedofolefins.2Theprimaryoxi
5、dantusedisoxoneandthereac-(ca.5Ctoambient).Theuppertemperaturelimitresultstionsareusuallyperformedat0Cinthepresenceofabase.fromtherelativelyfastdecompositionofoxoneinbasicInadditiontoanorganicsolvent,usuallyacetonitrile,watermediaatroomtemperature.Thelowerlimitisdeterminedisanessentialcos
6、olvent,requiredinordertoprovidesuffi-bytherequirementforanaqueoussolution(thenormalcientoxonesolubility.ratioofsolventsis(CH3CN/H2O;1:1);aqueousacetonitrilefreezesat8C.AnadditionaldrawbackarisingfromtheWehavepreviouslydescribedourapproachtonewtypesofdependencyonoxoneisthelargequantityofinor
7、ganicsaltcyclicchiraliminiumsalts,functionalisedwithchiralunitsbyproductsproducedinthereaction.atthenitrogenatom.3Theseenantiomericallypureiminiumsaltshavebeensuccessfullyemployedinthecatalyticasym-Wehaverecentlydescribednewreactionconditionsforimi
