No. 9.] (9) 45

62. On a•Monoaminohinokitiol.

By Tetsuo NozoE and Egai SERE. Chemical Institute, Faculty of Science, ; and Pharmacological Institute, Medical Faculty, Kumamoto University. (Comm. by R. MAJIMA,M.J. A., Nov. 13, 1950.)

The authors, some time ago, recognized the formation of an amphoteric substance, besides p-toluidine, during reduetion of p- tolyl-azo- (I) with zinc dust and acetic acid°, although it could not be obtained in a pure state. Later, by the reduction of (I) with sodium hydrosulfite, similar substance (II), m.p. 131-132°, soluble in both acids and alkalies, was obtained. (II) gave a picrate, m. p. 144- 145°, and diacetate, m. p. 141-142°, and was found, from their analytical values, to be monoaminohinokitiol. In order to distinguish it from isomeric monoamino compounds obtained by the reduction of several kinds of mononitrohinokitiols°'', (II) was designated as a-aminohinokitiol. In spite of being an unsaturated 7-membered amine, (II) can be diazotized, and leads to various halogen and cyano compounds by the Sandmeyer reaction, although the yield is poor, and resinous substance is formed due to the unstability of the diazonium salt which easily decomposes with liberation of N2. The reaction products all give red coloration with FeCI;; in ether solution, showing that they form inner complex salts, so that they are true substitu. tion products of hinokitiol (IIIa) still retaining the nucleus.

The ehloro compound (Tub), m.p. 118.5-119.5°, obtained from (II), was proved to coincide with oc-monochloro derivative 3', m.p. 118-119°, obtained by the direct chlorination of (IIIa). The bromo compound (Tile), m.p. 102-103°, did not coincide with either of the monobromo compounds (o:c m. p. 56°; / : m. p. 42°)4' obtained by the direct bromination of (IIIa), so that it was designated 7-mono- bromohinokitiol. The iodo compound (IIId), m.p. 87-88°, also differed from the known monoiodo compounds (02: 49° ; ,9: oil) 3' and was designated y-monoiodohinokitiol. The three halogen compounds (9) 46 T. NozoE and E. SEBE. [Vol. 26,

(Tub, Tile, IIId) here obtained all differ from similar isomers ob- tained to date which are assumed to possess halogen atom in the o- or o'- position, as they do not give crystalline compound with aniline and p-toluidine, but combine with aliphatic amines, such as diethylamine and ethylenediamine, to give crystalline compounds. Nozoe, Kitahara, et al.~' found that the amino compound (II) was identical with that of m.p.130-131°, obtained by the reduction of -nitrohinokitiol, m.p. 158°, a fourth isomer assumed to be p-substituted, which usually formed in only small amounts as a by-product during nitration of (IIIa). This nitration most easily gives a-mononitrohinokitiol, m.p. 56° , and its reduction, as well as that of $-and y-mononitro compounds ($: m.p. 125°: y : m.p. 155°), which are assumed to be o'- as well as o-substitute, yield isomeric monoamino compounds of hinokitiol ($-monoamino, m.p. 99° from a-mononitro compound ; y-monoamino, m.p. 121° from both B- and y-mononitro compound). From these facts, it has become most probable that the mono- amino compound, m. p. 131-132°, is p-aminohinokitiol (II), and, therefore, formula (I) would apply to p-tolyl-azo-hinotitiol. This has made it easier to understand the reason why (I) should easily undergo rearrangement to hinopurpurin, being different from the p-tolyl-azo-derivatives of tropolor e and o-isopropyltropolone (i.e. a- ).5 Conjectures were made as to the reason why, contary to halogens and nitro group, a large group, such as diazo, should attack the p-position where the steric interference is fairly larger than at o'-position. It was assumed'' that, in the case of a fully ionic diazonium cation, it would more easily react through the " p-tropoquinonoid " transition state (IVa) , rather than with " o-tro- poquinonoid " structure (IVb), because the reasonance stability of the former would be larger than that of the latter. In its transi- tion state, the steric interference of adjacent isopropyl group would not be so great, or rather, its inductive or inductomeric effect (+1) would exert an advantageous influence on the p-position.

Since a small amount of p-chloro compound is in all cases ob- tamed in the direct chlorination of (IIIa), various experiments were made to find if p-bromo compound would be obtained by No. 9.] On a-Monoaminohinokitiol. (9) 47

bromination. A two mol, equiv. of bromine was applied to hot, glacial acetic acid solution of (IIIa) but, only a-monobromo (i.e. o'- Br-) compound, and a small amount of a monobromo compound, m.p. 97-98°, was obtained, rather than the expected di-substitutes. This must mean that in the higher temperature, it has become difficult for a halogen atom to enter o- or p-position7' due to the steric interference of the isopropyl group. This in turn had pre- vented di-substitution and had caused a mono-substitution at m- position or at the side chain to a certain extent. However, no definite proof of the structure has yet been obtained. Cyanohinokitiol (IIIe), m.p. 103-104°, is not affected by mineral acids, but is easily hydrolyzed by alcoholic potash to a substance, m.p. 152-153°, which is not easily esterified, is not a carboxylic acid, but seems to be an acid amide. Azoxyhinokitiol, m.p. 177- 178° (decomp.), and azohinokitiol, m.p. 286-287° (decomp.), were obtained by the oxidation of the amino compound (II) by ammonium persulf ate.

Experimental

a-Aminohinokitiol (II) :-10 g. of (I) is dissolved in 250 cc. of 10 / NaOH, 50 g. of Na2S~O4.2H;0 added, and stirred vigorously for 3-6 hrs., by which crystals separate out. The filtrate is ex- tracted with several lots of ether to remove p-toluidine, cooled with ice, and conc. HCl added slowly. Majority of the yellow substances that separate out during this addition dissolve again but some insoluble matter precipitates by standing at room temperature. This is filtered and to the filtrate is added an aq. soln. of 25 g. of NaHCO; , by which yellow precipitate is obtained. The mixture is allowed to stand overnight, filtered, residue washed with water and dried. This residue (3-4 g.) is extracted with benzene and its soluble portion is recrystallized to long yellow needles, m.p. 131- 132° (from benzene). Yields a purplish black precipitate with FeCl . Anal. Calcd. for C,oH,;}OWN: C, 67.03; H, 7.36; N, 7.81. Found : C, 7.25; H, 7.42; N, 7.85. Picrate : Yellow cryst., m.p. 744-145° (from ethanol). Anal. Calcd. for C,;;H,~;O,N4: C, 47.06; H, 3.92. Found : C, 46.96; H, 2.4, 3.87. Diacetate : Pale yellow, minute needles, m.p. 141-142° (from ethanol) ; doss not color by FeC1 but heating with it in aq. soln. yields bluish violet solution, partly precipitating a reddish brown complex salt. Anal. Caicd. for C,4H,7O4N: C, 63.87; H, 6.46; N, 5.32. Found: C, 63.41, 63.20; H, 6.41, 6.17; N. 5.20. a-Monochlorohinokitiol (IIIb) :-Obtained by the Sandmeyer reaction of (II), as pale yellow featherly crystals, m.p. 104-108°. (9) 48 T. NozoE and E. SEBE. [Vol. 26,

Repeated crystallization from benzene gives m.p. 118.5-119.5° . No depression of m.p. was found when this was mixed with the mono- chloro-compd.'' obtained by the direct chlorination of (IIIa). Anal. Calcd. for CIOH11O2CI : C, 60.45 ; H, 5.56. Found : C, 60.53 ; H, 5.57. Ethylenediamine salt : Yellowish needles, m.p. 131-132° (from petr. ether). 7•Monobromohinokitiol (lllc) : Obtained by Sandmeyer's method from (II) ; orange yellow needles, m.p. 102-103° (from benzene) ; ether soln. colors red with aq. FeCI.; soln. Anal. Calcd. for C,,,H„ O~Br : C, 49.38 ; H, 4.52. Found : C, 49.40 ; H, 4.54. Diethylamine salt : Yellowish orange needles, m.p. 120-121°, (from petr. ether). a.Monoiodohinokitiol (llld) :-Obtained by Sandmeyer's me- thod from (II) as pale yellow needles, m.p. 87-88° (from petr. ether). Its ether soln. colors red with sq. FeCI;. Anal. Calcd. for C11H110.2I: C, 41.38; H, 3.79. Found : C, 41.53; 41.55; H, 4.10, 3.91. Diethylamine salt : Yellow, granular crystals, m.p. 116-7° (from petr. ether). Cyanohinokitiol (IIIe) :-Obtained by Sandmeyer's method from (II) to pale yellow needles, m.p. 103-104° (from benzene). Anal. Calcd. for C11H110;N: C, 69.84; H, 5.82. Found: C, 70.05; H, 6.08. Hydrolysis Product of (tile) :-0.3 g. of (Tile) is dissolved in 5 cc. EtOH, 0.4 g. NaOH added, and boiled on a water bath for 5 hrs. Pale yellow needles, m.p. 152-153° (from dil. AcOH). Anal. Calcd. for C11H13O~N: C, 63.77; H, 6.28. Found : C, 63.71, 63.46; H, 6.02, 5.77. Esterification by the ordinary method produced no change. Azoxyhinokitiol :---1 g, of (II) is dissolved in 20 cc. of N/2 H.2SO4, 10 cc. water containing 1.3 g. of NH4-persulfate added drop- wise, and heated for 5 hrs. at 70-80°, when yellow substance precipitates out. After allowing the mixture to stand for 3 hrs., it is filtered, and the residue divided into ether-soluble (a) and -insoluble (b) portions. (a) is dissolved in 20/ AcOH and repeatedly crystallized to yellow needles, m.p. 177-178° (decomp.). Anal. Calcd. for C20H2205N2: C, 64.84; H, 5.94. Found : C, 64.51, 64.60; H, 5.94, 6.32. Azohinokitiol: Above-mentioned (b) is recrystallized from glacial AcOH to minute brown needles, m.p. 286-287° (decomp.). Anal. Calcd. for C20H2204N2: C, 67.80; H, 6.21. Found : C, 68.01, 67.88; H, 6.43, 6.29. ~•Monobromohinokitiol :-A glacial AcOH soln. of 16 g. (0.1 mole) of (II) is warmed on a water bath, a soln. of 30 g. (0.2 mole) No. 9.] On a-Monoaminohinokitiol. (9) 49

Bra in 20 cc. glacial AcOH is added dropwise, and refluxed for 2-3 hrs. The product is repeatedly recrystallized as its Na-salt and later freed at various fractions. The most difficultly soluble portion gives, by repeated recrystallization, pale yellow crystals of m.p. 54_550, which do not show depression of m.p. when fused with a-bromohinokitiol, m.p. 55-56°. The soluble portion gave long yellow needles which, by repeated recrystallization, gave pale yellow, leaflets, m.p. 97-98°. A mixed fusion of this crystal and that of (Tile), m.p. 102-103°, gave an m.p. of 70--75°. Anal. Calcd. for C,0H,IO2Br : C, 49.38; H, 4.52; neutr. equiv. 243. Found : C, 49.28; H, 4.39; neutr. equiv. 250. The authors wish to acknowledge with thanks for the Grant in Aid for Scientific Research by the. Ministry of Education, and the cooperation of Mr. Masao Inoue of the Kumamoto University and Mr. Eikichi Aoyagi of Miike Laboratory, Omuta, for the micro- and semimicroanalyses.

References.

1) Nozoe, Sebe, Kitahara, and Fujii : To be published. [Cf. Nozoe : Science of Drugs, 3, 174 (1949)]. 2) Nozoe, Kitahara, Kunioka, and Doi : The Proceedings : 26 (No. 9), (1950). 3) Nozoe, Sebe, and Iwamoto : To be published. 4) Nozoe, Mukai, and Takase : The Proceedings : 26 (No. 8), 19 (1950). 5) Nozoe, Seto, Kitahara, and Kunori : The Proceedings : 26 (No. 7), 38 (1950). 6) Nozoe and Yamane : To be published. 7) Nozoe : This Proceedings : 26 (No. 9), (1950).