In continuation of our studies of the mechanism of action of monoamine oxidase (MAO) using deuterium isotope effects as a tool,2-5 we have examined the effect of deuterium substitution on the carbons alpha and beta to the amine function of the substrate kynuramine (I and II) on the kinetics of oxidation by rat liver MAO. The a-bisdeuteriokynuramine (I) was prepared by lithium aluminum deuteride reduction of indoleacetonitrile,6 then ozonolysis according to the procedure of Weissbach et al.1 The 3-bisdeuteriokynuramine (II) was obtained by prolonged treatment of kynuramine dihydrobromide with excess deuterium oxide at 100°. Both substrates were labeled to the extent of at least 90% as determined by n.m.r. analysis. The MAO was prepared according to Hawkins8 and the rates of oxidation measured spectrophotometrically folloiving the procedure of Weissbach et aV The results are shown in Fig. 1, where it can be seen that the ratio of the slopes of the initial velocities / . is 2.1 when (I) is compared with kynuramine. The magnitude of this primary(1) This investigation represents a portion of the thesis submitted by J. M. in partial fulfillment of the requirements for the M.Sc. degree in Biochemistry.(2) B.
[reaction: see text] A photoinduced procedure for the 1,4-addition of indoles to enones is described. This reaction occurs with modest to excellent yield for cyclic and some acyclic enones. This reaction is experimentally simple, requiring only irradiation (UVA lamps, ca. 350 nm) of the reagents in a CH2Cl2 solution at room temperature, and avoids the necessity to use a Lewis acid. An important solvent effect was noticed, with CH2Cl2 and CHCl3 being the optimal solvents. Various substituents are tolerated on the indole moiety and an electronic trend was noticed, as electron-withdrawing groups can suppress this reaction. A mechanism involving single electron transfer between the enone triplet excited state and the indole is proposed and accounts for all experimental observations.
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