C.G. OPERRERGBR,L. C.PALMER, BURTONS. M.IRKS.\ND N. I filtrate was added 40 ml. of water, followed by sufficient ethanol, beiizene potassium hydroxide t o neutralize the glacial acetic acid and the acetic acid salt of the 2,6-dimethylpiperidine. T h e resultant mixture was extracted four times with ether with further solid potassium hydroxide added t o the solution after each extraction. T h e combined ethereal solution, after drying over anhydrous potassium carbonate, was fractionally distilled to yield 50 g. (88.5%) of product, b.p. 127-128' ( b . p . 127.5-128.25" prepared by reduction of 2,6)c=o lutidine with sodium and alcohol followed by separation of IV 0 hydrochloride isomers'3). The picrate was prepared by adding an ether solution of \CH?C~H, I1 the amine t o an ether solution of picric acid, arid melted a t The preparation of IY is similar to a recently re- 166-166.5" dec. ( m . p . of cis isomer, 162-164013). ported synthesis of l-benzoylamino-2,5-dimethyl- l-Nitroso-2,6-dimethylpiperidine.-The method used was from t h a t described by H a t t j who nitrosated dipyrrole. l 1 The preparation of V by the above pro- adapted methylamine. 2,6-Dimethplpiperidine (178 g., 1.58 moles) cedure is a new method for the synthesis of 1-am- was dissolved in 158.4 g. (1.6 moles) of concd. hydrochloric in0-2~5-dimethylpyrrole.The physical properties acid in 500 ml. of water. The temperature of the mixture and infrared spectra of I1 prepared by this method was kept a t 75" and stirred while 113.6 g. (1.6 moles) of sodium nitrite dissolved in 300 ml. of water was added as well as the picrate and tetrazene were identical 97% dropwise over a two-hour period. After addition the heatwith I1 and the respective derivatives prepared by ing and stirring were continued for a n additional two hours. the other methods. Since two of the methods of A yellow oily top layer was separated from the reaction synthesis of I1 involve reduction of a pyrrole ring mixture, while the bottom layer was extracted two times with ether. The combined ethereal washings and top layer catalytically, the cis configuration of the methyl were dried over anhydrous potassium carbonate, the ether groups are suggested. was removed and the remaining yellow oil fractionally disAll of the N-amino compounds (I, I1 and 111) give tilled to yield 162 g . (72.2y0) of product, b . p . 83-85" (2.5 tetrazenes. I was oxidized with yellow mercuric rnm.), probably the cis isomer. The freshly distilled oil on oxide to give the tetrazene in 7GY0 yield. I11 was standing tends to crystallize, m.p. 33-35". 4na1.I4 Calcd. for C7HL4NaO:C, 59.15; H , 9.86; S , oxidized with quinone according to the general di- 19.72. Found: C,59.22; H, 10.08; S , 19.72. rections of Wieland and F r e ~ s e l . ~ I1~ was conStarting material t h a t has not reacted can be recovered verted to the tetrazene with potassium permanga- by making the aqueous lower layer basic and extracting nate in acetone. This compound was previously four times with ether. N-Nitrosodibenzv1amine.-The method emDloved was reported by Tafel and Neugebauers by oxidation of similar t o t h e one used in the preparation of l:ni&-oso-2,6an impure N-amino compound with mercuric ox- dimethylpiperidine. T h e product was a yellow crystalline ide. precipitate which, after recrystallization from ligroin, melted Deamination of I over jyOrhodium on alumina a t 60-61' (XOOj,), (m.p. 61", prepared b r nitrosation of dicatalyst proceeded with facility and gave the piper- benzylamine, no yield given'6). 1-Amino-2,6-dimethylpiperidine .-The procedure was idine in yield. similar to t h a t reported by Schueler and Hanna6 although An inspection of the infrared spectra revealed the the specific reaction conditions included herewith are irnease of distinguishing between NH and NH2 portant for successful results and safety. One pound of groups. The infrared spectrum of l-arnino-2,6-di- dry ether was added to 26.6 g . (0.70 mole) of freshly ground lithium aluminum hydride and t h e apparatus was arranged rnethylpiperidine revealed a medium strong peak in so t h a t outside moisture was excluded. This slurry was the 6.25 p region, indicative of an NH2 bending allowed t o stir a t reflux for one hour, then 71 g. (0.5 mole) of frequency. Furthermore, two peaks were also l-nitroso-2,6-dimethylpiperidine dissolved in 25 ml. of noted in the 3 p area. 2,G-Dimethylpiperidine re- ether was added dropwise over a 2-hour period to the icereaction mixture. The reaction mixture was allowed vealed only one peak in the 3 p area and no absorp- cooled t o stir a t 0 " for one hour after the addition, at which time tion in the 6.25 p region. it was allowed t o come slowly t o room temperature. During Comparison of the spectra of 1,l-dibenzylhydra- the warming period (approximately l / p hour) frothing and zine and dibenzylamine with their respective ana- a general exothermic reaction occurs. Recooling with an ice-bath was necessary. and after one hour the reaction was logs in the piperidine series, indicated similar peaks completed. Excess lithium aluminum hydride was dein the 3 p area. I n the 6.25 p area, however, there stroyed by adding small amounts of water dropwise t o the is a phenyl absorption, and in carbon tetrachloride cooled reaction miuture. The water addition was consolution it appears that the phenyl and NH2 ab- tinued until the reaction mixture was completely white. 0
0
+
~
%yo
(10) G G E v a n s , THISJ O W R V A L , 73, 5230 (1951) (11) H L Yale, K Losee. J Martins M Holsmg, F M Perry We are grateful for a small and J Bernstein, zbzd , 7 6 , 1933 (1953) sample of this benzoate donated h v D r Yale of the Sqiithh In.;titnte tor Medical Rrsrarch
(12) All melting points are corrected (13) A. Marcuse a n d R. Wolfenstein, Ber., 32, 2525 (1899). f l 4 ) Analyses by Dr K. Ritter, Rasel. Switzerland. and Dr Schwarzkopf, S e w York. iY Y. (15) 'I' Curtius and H. Franzen, R P Y ,3 4 , 362
