A laser flash photolysis study on 2-azido-N,N-diethylbenzylamine - The reactivity of iminoquinone methides in solution

Photolysis of 2-azido-N,N-diethylbenzylamine (1) in acetonitrile solution i n the presence of various quenchers yields products of common nitrene chemi stry (that is, derived from a didehydroazepine or a triplet nitrene), toget her with products arising from trapping of stereoisomeric iminoquinone meth ides, These intermediates are formed in a monophotonic process, by dediazot ation of the precursor combined with a 1,4-hydrogen shift. The reactivity o f the iminoquinone methides (IQM) towards a variety of quenchers, including dienophiles and various nucleophiles, has been explored, using acetonitril e, DMF and n-hexane as solvents. IQM reacts efficiently with electron defic ient dienophiles [k(q)(maleic anhydride) = 2.4(.)10(7) M-1 s(-1), but not w ith simple olefins such as cyclohexene. IQM shows low to medium reactivity towards simple primary or secondary amines [k(q)(n-propylamine) = 6.4(.)10( 4) M-1 s(-1), medium reactivity with sterically unhindered simple alcohols [k(q)(methanol) = 4.6(.)10(6) M-1 s(-1)], and high to very high reactivity towards thiols [k(q)(n-dodecanethiol) = 1.1(.)10(9) M-1 s(-1)], diols, and triols [k(q)(glycerol) = 1.5(.)10(8) M-1 s(-1)], and sugars [k(q)(D-glucose ) = 1.0(.)10(9) M-1 s(-1)]. IQM also reacts rapidly with cytosine: k(q)(cyt osine) = 3.4(.)10(8) M-1 s(-1), while the reaction with adenine or thymine is less efficient [k(q)(adenine)= 6.4(.)10(7) M-1 s(-1), k(q)(thymine)= 7.7 (.)10(6) M-1 s(-1)].