Chemistry of the aminochromes. Part XI. Studies on 2-methylaminochromes

Abstract

2-Merhyladrenochromc and 1-crhyl-2-n~crl~ylnoradrenocl~ron~c havc been prcpared by oxidation of 3.4-dihydro.xyephcdrinc and 3,4-dit1ydro.xyhon~ocpI~cdrinc wirh silvcr oxidc. The corrcspondinq 7-iodoaminocl~ron~es were obtained when the oxidations were carried out with potassium iodate.-he expected 3,5,6-triacetoxyindoles were formed by treatment of these aminochromes with acetic anhydride and pyridine and the corresponding 5,6-diliydroxyindoles (isolated as their diacetyl derivatives) were obtained by reduction of the aminochromes with sodi~uii borohydride or sodium hydrosulfite. An improved procedure for the synthesis of 3,4-dihydroxycphedrine (a-~nethyladrenaline) is also described.Canadian Journal of Chcmirtry, 47, 2003Chcmirtry, 47, (1969 Onlv one 2-alkvl-substituted amii~ochrome had bken isolated hs a crystalline solid at the time that this investigation was begun. Bu'Lock and Harley-Mason obtained a deep-red crystalline product, described as 2-iodo-2-inethylnoradrenochrome on oxidation of a-methylnoradrenaline (3,4-dihydroxynorephedrine) with potassium iodate (1). It has subsequently been shown that, like all other iodoaminochromes, this product is a 7-iodo derivative (i.e. 7-iodo-2-methylnoradrenochrome (1)) (2). 2-Methylnoradrenochrome (2) (I), 2-ethylnoradrenocl~rome (3) (3), and 2-methylnorepi~~ocl~rome (4) (4) have been prepared in solution and a monosemicarbazone of 2 has been isolated as a crystalline solid (1).The synthesis and some properties of 4-methyladrenochrome (5) and 7-methyladreno-1, RI = R4 = H ; Rz = CH3; R 3 = OH; R~ = 1. 2, R I = R4 = R7 = H ; R2 = CH3; R3 = OH. 3, R I = R4 = R7 = H ; Rz = C ' H~; R~ = OH. 4, RI = R3 = R4 = R 7 = H ; R z = C H~. 5, RI = R4 = CH3; R 2 = R7 = H ; R3 = OH. 6 , R1 = R7 = CH3; Rz = R,, = H; R~ = OH, 7, RI = R ? = C H 3 ; R 3 = O H ; R, , = R~ = H, 8, RI = C1H5; RZ = CH3; R 3 = OH; R~ = R~ = H, 9, R I = R2 = CH3; R3 = OH; R4 = H ; R7 = 1. 10, R1 = CZHS; R2 = CH3; R, = O H ; R,, = H ; R~ = I.