A -Methylacridone

Classical chemiluminescence from lucigenin (20) is obtained from its reaction with hydrogen peroxide in water at a pH of about 10 Qc is reported to be about 0.5% based on lucigenin, but 1.6% based on the product A/-methylacridone which is formed in low yield (46). Lucigenin dioxetane (17) has been prepared by singlet oxygen addition to an electron-rich olefin (16) at low temperature (47). Thermal decomposition of (17) gives of 1.6% (47). 

Riehl et al. also characterized the CL system lucigenin-hydrogen peroxide-A-methylacridone in the presence of different cationic surfactants such as HTAC, S-ClV-dodecyl-A lV-dimethylammonio) propane-1-sulfonate, and DODAB [41], Enhancement factors (ratio between CL intensity in the presence of organized medium and CL intensity in the absence of organized medium) of CL intensity were found of 3.4, 2.5, and 1.6, respectively. The alterations in CL intensity are explained in terms of the effect of the different surfactants on the rate of the reaction and on excitation efficiency. 

A number of simple acridones have been obtained from new sources. Thus, acridone itself is a constituent of Thamnosma montana,13 and minor components of the root bark of Teclea verdoorniana include l,3-dimethoxy-A/-methylacridone (29 R = Me) and tecleanthine (30).12... 

A quite broad range of Lewis acid strengths was evaluated by comparing their effect on the shift of the fluorescence of complexes with A-methylacridone. " The shifts also correlated with the capacity of the Lewis acid to facilitate the reduction of... 

The bisacridinium salt 41 (lucigenin), on oxidation with an alkaline H2O2 solution, displays an intensely green chemiluminescence. The light emission is due to the excited state of A-methylacridone 43, formed by an electrocyclic ring opening of the initially formed dioxetane 42 (see p 47) ... 

The alkaloids melicopicine from Melicope fareana [86], acronycine from Acrony-chia baueri [87, 88], and rutacridone from R. graveolens (Rutaceae) typify some of the structural variety that may then ensue. For instance, radioactivity biosynthetic studies on R. graveolens, using [1- H]DMAPP (dimethylallyl diphosphate), demonstrated that 1,3-dihydroxy-A-methylacridone reacted with DMAPP upon mediation of a monoprenyl aryl transferase. The formed prenylated acridone glycocitrine-H in turn cyclized to give the dihydrofuran portion of rutacridone. Compounds 21 and 22 are hypothetical intermediates (Figure 6.18) [89]. 

Figure 6.18 Hypothetical reaction sequence for the conversion of 1,3-dihydroxy-A -methylacridone into rutacridone.

A -methylacridone in the singlet excited state. This compound comes back to the ground state, producing a sustained high-intensity CL, according to the scheme ... 

Trihydroxy-4-methoxy-10-methyl-2,8-bw(3-methylbut-2-enyl) acridin-9( 10/7)-one, 1,5 -dihydroxy-2,3 -dimethoxy-10-methyl-9-acridone, 2,3-dihydro-4,9-dihydroxy-2-(2-hydroxy-propan-2-yl)-l 1-methoxy-10-methylfuro[3,2-b]acridin-5(1077)-one, 3,4-Dihydro-3,5,8-trihydroxy-6-methoxy-2,2,7-trimethyl-2/7-pyrano[2,3-a]acridin-12(7/7)-one, 3,4-Dihydro-3,5,8-trihydroxy-6-methoxy-2,2,7-trimethyl-2/7-pyrano[2,3-a]acridin-12(7/7)-one, l-hydroxy-3-methoxy-10-methyl-9-acridone, 1 -hydroxy-2,3 -dimethoxy-10-methyl-9-acridone, 1 -hydroxy-A-methylacridone, l-methyl-2-[(Z)-pentadec-9-enyl]quinolin-4(l/7)-one,... 

A-Methylacridones are synthesized from 2-(A-methyl-A-phenylamino)benzaldehydes in DMF using Sc(OTf)3 as the catalyst and Na2S04 as additive via dehydrogenative cyclization. There are two primary processes in the transformation the aldehyde first coordinates with Sc(OTf)3 and induces the aromatic electrophilic substitution (5eAt) reaction to form the active intermediate Af-methyl-acridin-9-ol, which is then quickly oxidized in situ to afford the acridones. ... 

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