Incarcerated Carbenes

摘要

Carbenes(dIValent derIVatIVes of carbon)are,for the most part,fleeting intermediates.The search for persistent carbenes has only recently been successful.Intrinsic stabilization by ami-no groups(Arduengo,Alder)and phosphanyl groups(Bertrand) provided "bottleable" singlet carbenes such as 1 and 2(Scheme 1).Steric protection,together with electron delocalization,led to long-lIVed triplet carbenes(To-mioka).The success of this approach is illustrated by carbene 3,which currently holds the record in lifetime(14 days at 25 deg C).