Vinylogous amides have proved useful as starting compounds

for the preparation of polycyclic conjugated, nonbenzenoid

π-electron systems [¹]

Hafner, Klaus

Neuenschwander, M.

Vinylogous amides have proved useful as starting compounds
for the preparation of polycyclic conjugated, nonbenzenoid
π-electron systems [¹]

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Ethynylogous Amides and Urethanes

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pound (11). the primary C-6 mesyloxy group can be S O ~ V O -  lyzed selectively: sodium azide in dimethylformamide (3 h,  75 "C) gives the 6-azido compound (12) [m.p. 148-150 "C, [a];5 = +162 (c  = 1, CHCI3), yield 84 %I; similarly, sodium benzoate in dimethylformamide (5h, 80 "C) gives analytically and chromatographically 6 1  pure methyl 2,3,6-tri-O-benzoyl- 4-O-mesyl-c~-~-glucopyranosyl (13) in amorphous form [[.I'd = +139 (c = 1, CHC13), yield 92 %]. Solvolysis of the C-4 mesyloxy group in (13) by heating with sodium azide in dimethylformamide (60 h, 100 "C) and subsequent de-0- benzoylation with methanolic ammonia affords methyl 4- azido-4-deoxy-a-~-galactopyranoside (61, R = H [m.p. 153-155 "C, [a12 = +120° (c = 0.5, CH3OH), yield 64 741. Hydrogenation of (61, R = H, followed by N-acetylation yields a product whose melting point, [ a ] ~ ,  and IR spectrum are identical with those of (10). The galacto configuration of ( I )  and ( S ) - ( I O )  follows from the method of preparation [6bl and from N M R  spectroscopic data. The acetyl resonances obtained for ( I )  [T = 7.91, 7.94 (2). and 8.01 in CDC13; 7.96, 7.98, and 8.08 (2) in [D6]- DMSO] indicate171 the absence of axial acetoxy and equa- torial acetylamino groups. Analysis of the ring CH protons effected at  100 MHz in CDC13 [81 gave for H-4 at  T = 5.27 a quartet with J34 = 4.0 and J4NH = 10.0 Hz, each line being broadened by coupling with H-5 (J45 = 1 Hz). This quartet is simplified to a 4-Hz doublet by irradiation at  the resonance frequency of the N H  doublet (T = 3.61, 10 Hz) and to a 10 Hz  doublet by irradiation at  the resonance frequency of the H-3 quartet (T = 4.72). Attempts to  obtain (2) by acid hydrolysis of ( I )  or  (10) 14 N HCI, 100 "C] and subsequent N-acetylation have so far failed. Apparently ring contraction giving the pyrrolidine sugar occurs under the conditions necessary for glycoside cleavage 191. [Z 757 IE] Received: March 20, 1968 German version: Angew. Chem. 80, 441 (1968) [*] Doz. Dr. F. W. Lichtenthaler and Dip1.-Ing. P. Heidel Institut fur Organische Chemie der Technischen Hochschule 61 Darmstadt, Schlossgartenstr. 2 (Germany) [l] T .  Kanzaki, E. Higashide, H.Yamamoto, M .  Shibata, K. Na- kazawa, H.  Iwasaki, T. Takewaka, and A .  Miyake, J. Antibiotics (Tokyo), Ser. A, I S ,  93 (1962); J .  M .  Clark jr .  in D. Gottlieb and P. D.  Shaw: Antibiotics. Springer, Berlin, Heidelberg, New York 1967, Vol. 1, p. 259. 121 J.  J. Fox, Y. Kuwada, K .  A .  Watanabe, T. Ueda, and E. B. Whipple, Antimicrobial Agents and Chemotherapy 1964, 518. [3] H. Iwasaki, J. pharmac. SOC. Japan [Yakugaku Zasshi] 82, 1380 (1962); Chem. Abstr. 59, 757 (1963). [4] K.  Freudenberg and E. Plankenhorn, Ber. dtsch. chem. Ges. 73, 621 (1940). [5] Thin-layer chromatography on silica gel HFx4 (E. Merck AG., Darmstadt) with ethyl acetate-ethanol-water (15:2:1) as eluant. Detection by iodine vapor or spraying with 2 yo methano- lic perchloric acid and heating to 100 "C. [6a] J .  Hill, L.  Hough, and A .  C .  Richardson, Proc. chem. SOC. (London) 1963, 314. [6b] For the steric course of solvolysis of equatorial C-Qmethane- sulfonyloxy groups see Y. Ali and A .  C. Richardson, Chem. Com- mun. 1967, 554; also ref. [6a, 91. [7] F. W .  Lichtenthaler and P .  Emig, Tetrahedron Letters 1967, 577; Carbohydr. Res. 6 (19681, in the press. [8] We thank Dr. U .  Scheidegger, Varian AG., Zurich, for measurement of the 100 MHz spectrum. [9] C.  L.  Stevens, P .  Blumbergs, and D.  H. Otterbach, J. org. Chemistry 31, 2817 (1966). Ethynylogous Amides and Urethanes I**] By K. Hafner and M. Neuenschwander [*I Vinylogous amides have proved useful as starting compounds for the preparation of polycyclic conjugated, nonbenzenoid x-electron systems "1. The hitherto unknown ethynylogous amides should provide a synthetic route to  novel unsaturated ring systems; the study of the chemical and physical proper- ties of these compounds was therefore of interest. Ethynylogous amides and urethanes can be prepared easily and in good yields from the corresponding vinylogous compounds ( I ) .  The bromination of 3-(dimethy1amino)prop- f 3) (4)  (a), R = H (b), R = CH3 95 54-56 294; 4.39 95 I 63-65 1 305; 4.01 75 277; 4.23 70 1 I - 3 7  1 255; 4.08 2165 2145 2165 2195 1.23/S/1 H; 2.781811 H; 6.691816 H. 2.301811 H; 6.771816 H; 7.67/S/3 H. 2.23/S/1 H; 6.271813 H; 6.821816 H. 0.92/S/1 H; 6.95/S/6 H. 7.021816 H; 7.79/8/3 H. 7.10/S/6 H. 6.331~13 n; Angew. Chem. internat. Edit. / Vof. 7 (1968) 1 No. 6 459 Hafner, Klaus: Ethynylogous Amides and Urethanes aus Angewandte Chemie international Edition 7, Jahrgang 1968, Nr. 6 Copyright © 1968 Wiley by Verlag Chemie, GmbH, Germany2-en-1-a1 ( l a )  121, 4-(dimethylamino)but-3-en-2-one (lb) 131, and methyl 3-(dimethylamino)acrylate (Ic) [41 leads almost quantitatively to  the hydrobromides (2). which react with triethylamine to  give the bromine derivatives (3) in yields of more than 90 % [51. The acetylenes (4) are obtained from (3) in yields of about 70 % by elimination of HBr with potassium rert-butoxide [61. Compound (4a), a pale yellow oil, is stable for long periods only below -5OoC, whereas (4b) and (4c) can be kept for several hours at  room temperature. Received: January 15, 1968 [ Z  713a IE] German version: Angew. Chem. 80, 443 (1968) Publication delayed at the authors' request [*I Prof. Dr. K. Hafner and Dr. M. Neuenschwander Institut fur Organische Chemie der Technischen Hochschule 61 Darmstadt, Schlossgartenstr. 2 (Germany) [**I M. N. is grateful to the Schweizerische Siiftung fur Stipen- dien auf dern Gebiete der Chemie for a grant. We thank Fraulein M .  Ruppert for her skilful experimental assistance. [l] K. Hafner and J.  Schneider, Liebigs Ann. Chem. 624, 37 (1959); K. Hafner and G. Schneider, ibid. 672, 194 (1964); K. Haf- ner and M .  Kreuder, Angew. Chem. 73,657 (1961); K.  Hafner, R. Fleischer, and K. Fritz, Angew. Chem. 77, 42 (1965); Angew. Chem. internat. Edit. 4, 69 (1965). [Z] F. Wille and F. Knorre, Chem. Ber. 85, 841 (1952); German Pat. 944852 (1956), Chem. Abstr. 52, 16300b (1958). We are grateful to Badische Anilin- und Sodafabrik AG., Ludwigshafen, for the supply of compound ( la ) .  [3] E. Benary, Chem. Ber. 63, 1573 (1930). [4] Propiolic acid after V. WOK Chem. Ber. 86, 735 (1953); methyl ester by refluxing for two days with 10% conc. H2SO4 in anhydrous methanol; (tc) by addition of dimethylamine to methyl propiolate in tetrahydrofuran at 20 "C. [5] Correct analytical data were obtained for all the compounds described. [6] Overall yield for all the steps. The acetylenes were purified by distillation in a bulb tube at 10-4 torr and oven temperatures of 20°C (4a), 40°C (4b), and 30°C (4c). The yields decrease rapidly at higher temperatures. A New Rearrangement of Substituted 3-Aminopropenals I* *I By M .  Neuenschwander and K. Hafner [*I 3-(Dimethylamino)prop-2-yn-l-al (1) reacts with an equi- molar quantity of HCl in anhydrous tetrahydrofuran at 0 O C  to  give the reactive aldehyde (2), R = CI [I], which rearranges during isolation to  form isomer-free trans-3-chloro-N, N- dimethylacrylamide (3a), R = CI (yield 80 %) [31. The strong band in the UV spectrum of ( 3 ~ ) .  R = CI, occurs at  216 nm (n-hexane), a position characteristic of amides of similar structure, and the AB system of the vinyl protons in the N M R  spectrum occurs at  T = 2.77 and 3.32 (J = 13 Hz141); hydrogenation of (3a), R = CI, with Pd black (2OOC in benzene) yields N,N-dimethylpropionamide. The aldehyde (2). R = OAc, cannot be isolated in the analogous reaction of (1) with glacial acetic acid; the product obtained (80 % yield) is isomer-free 121 cis-3-acetoxy-N, N-dimethylacryl- amide (3b), R = OAc [NMR in CDC13: T = 2.58/D (J = 7.5 Hz)/l H; T = 4.43/D/1 H;  T = 6.90 and 6.94/2S/6H; T = 7.75/S/3H], which rearranges when heated to  6OoC to give the thermodynamically more stable frans isomer (3a), R = OAc W M R  in CDCl3: T = 1.73/D ( J  = 12 Hz) / lH;  T = 3.73/D/1 H;  T = 6.93/S/6H; T = 7.79/S/3 HI. Compound (3b), R = OAc, can be converted into 3-acetoxy-N,N-dime- thylpropionamide by hydrogenation(Pd/Hz. 2OoC in benzene). Compound ( I )  reacts highly stereoselectively 161 with an  equi- molar quantity of diethylamine or with an  excess of methanol or ethanolrsl to  give the aldehydes (2) ,  R = N(CzH&, OCH3, and OC;H5 respectively, which can be isolated since their tendency toward rearrangement is less pronounced than that of the adducts of ( I )  with HCl or acetic acid, and decreases in the order OCH3 > OCzH5 > N(CzH5)z. +HR (CH3)2N, 5? ( c H ~ ) ~ N - c - c  -C -H - ,C = C H - C - H R ( 11 , (21 Whereas only traces of 3-(diethylarnino)-3-(dimethylamino)- prop-2-en-1-a1 (2). R = N(CzH5)z. rearrange at  60 to  80 "C, 3-methoxy-3-(dimethylamino)prop-2-en-l-al (2), R = OCH3, bellow oil, yield 90 %. N M R  in CDCl3: T = 0.72/D (J = 8Hz)/l H ;  T = 5.46/D/l H; T = 6.16/S/3H; T = 7.06/S/6H] is converted when heated at  60 "C in CHCI3 into the isomeric methyl truns-3-(dimethylamino)acrylate (41, R = OCH3 157 % yield, m.p. 46-47OC, Amax in CHzC12: 278 nm, log E = 4.28, N M R  in CDCI3: T = 2.57/D (J = 13 Hz)/l H; T = 5.50/D/1 H;  T = 6.35/S/3 H; T = 7.09/5/6H], the constitution of which was verified by comparison with (4), R = OCH3, prepared from methyl propiolate and dimethylamine. The new rearrangement of 3-aminopropenal derivatives (2) evidently proceeds with high stereoselectivity; a four-mem- bered ring intermediate or a corresponding transition state is probably involved. The configuration of the aldehyde (2), which is important for the elucidation of the mechanism 171, cannot be established from the above results. We are now proceeding with the further study of this reaction. Received: January 15. 1968 [Z 713b IE] German version: Angew. Chem. 80, 444 (1968) Publication delayed at the authors' request -. ~~ [*] Dr. M. Neuenschwander and Prof. Dr. K. Hafner Institut fur Organische Chemie der Technischen Hochschuie 61 Darmstadt, Schlossgartenstr. 2 (Germany) [**I M .  N,  is grateful to the Schweizerische Stiftung fur Sripen- dien auf dem Gebiete der Chemie for a grant. We thank Fraulein M .  Ruppert for her skilful experimental assistance. [l] The aldehyde (2),  R = C1, can be obtained in the impure state by careful working-up [UV in CHzC12: Amax = 297 nm; NMR in CDC13: T = 0.45/D/1 H and T = 4.80/D ( J =  7 Hz)/l H; T = 6.81/S/6 HI. [2] Purity checked by NMR spectra. [3] Similarly, the addition of HCl to 3-(N-methylanilino)prop- 2-yn-1-a1 (NMR in CDCI3: T = 0.73/S/1 H; T approx. 2.75/M/5 H; T = 6.62/S/3H; IR in CC4: v c = c  = 2170 cm-1) leads by rearrangement to trans-3-chloro-N-methylacrylanilide [NMR in CDC13: T = 2.3-2.9/M/6H, including T = 2.64/D/(J = 13 Hz); T = 3.78/D (J = 13 Hz)/l H; T = 6.63/S/3 HI. 141 For coupling constants of similar compounds, cf. E. Winter- feldt and H. Preuss, Chem. Ber. 99, 450 (1966). [5] Since the reaction rate in dilute equimolar solutions is too slow, the reactions was carried out in the corresponding alcohol. [6] According to the NMR spectra, the adducts (Z), R = N(CzH&, OCH3, OCzH5, are formed with a stereoselectivity of about 90 %. [7] For the steric course of additions to CEC bonds, cf. R. Huis- gen, B. Giese, and H.  Huber, Tetrahedron Letters 1967, 1883 (further references cited); E. Winterfetdt, Angew. Chem. 79, 389 (1967) (further references cited); Angew. Chem. internat. Edit. 6 ,  423 (1967). Preparation of 2,4,6-Tri-tevt-butylpyrylium Tetrafluoroborate, 2,4,6-Tri-tert-butylpyridine, and 2,4,6-Tri-tert-butylphosphorin By K. Dirnroth and W. Mach[*] Pyrylium salts substituted by tert-butyl groups in the 2,4,6- positions have not previously been known. The synthesis of such a salt, which we describe here, made possible the prepa- 460 Angew. Chem.'internat. Edit. / Vol. 7 (1968) / No. 6 

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Ethynylogous Amides and Urethanes

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