| |
[摘要]：The authors present a novel synthetic strategy to 2,2-dialkoxy-3-oxochlorins [M = 2H, Ni(II), Cu(II)] (i.e., acetaloxochlorins). Reaction of the corresponding 2,3-dioxochlorin with stoichiometric amts. of Ag triflate (AgOTf) in the presence of excess alc. yields the desired acetaloxochlorins within several hours of reflux in up to 90% yield for n-alcs., and in 25-89% yields for functionalized alc. substrates. Similar reaction conditions applied to 2-diazo-3-oxochlorins generates the 2,2-dialkoxy-3-oxochlorins (12-60% yields) accompanied by alkoxyporphyrins (10-27% yields). Electronic spectroscopy reveals for the acetaloxochlorins characteristic p-p* absorption features throughout the visible region and their x-ray crystal structures exhibit marked distortion from planarity of the p-conjugated macrocycle due in part to the steric bulk at the periphery. |
|
