NOVEMBER, 1963 Paper chromatograms developed in irrigants A and B and sprayed with indicator C revealed monoacetone D-glucose as the only sugar derivative; yield, 100%; m.p. 159-160°, undepressed when admixed with authentic sample; [ c Y ] ~ ~-12.3 D ( c 6.5, in water). Pure monoacetone D-glucose was obtained by dissolving the undried crystalline mass obtained above in 100 ml. of warm ethyl acetate. Incompletely dried monoacetone D-glucose preparations dissolve rapidly in a minimum of ethyl acetate, whereas thoroughly dried preparations are difficult to solvate. Cooling the ethyl acetate solution to 0" gave a pure white crystalline product in90yoyield; m.p. 161'; [ c Y ] ~ ~- 1D 1 . 6 ( ~ 2 . 5 , i n w a t e r ) .
KOTES
O 'QOH
3231
AcoQBr
-
3,4,6-Tri-O-acetyl-2-arnino-2-deoxy-a-~galactopyranosyl Bromide Hydrobromide' M. L. WOLFROM, W. A. CRAMP, AND D. HORTON
the ~ e l d o m - u s e dmethod ~ , ~ of Colleylofor preparation of 2,3,4,6-tetra-0-acety~-a-~-glucopyranosy~ chloride. The reaction is capricious, but under carefully controlled conditions11 good yields of the aminoglycosyl halide Received May 6, 1965 are obtainable. When applied to 2-amino-2-deoxy-aD-galactose hydrochloride (I) under the conditions of Peracylated glycosyl halides are valuable interWolfrom and Shen Han" for the D-glucose analog, a mediates in a wide range of syntheses12but such derivadark red crystalline product, exhibiting a poor analysis tives of the 2-amino-2-deoxy sugars suffer from two for 11, was obtained in modest yield; a t lower temperaimportant limitations as general intermediates in tures reaction was incomplete, even a t extended resynthesis. It is difficult or impossible to remove the action times. Conditions were established, with heatN-acyl blocking group after a coupling reaction has ing a t 5 5 O , where about 60% of the starting material been effected, with, for example, the peracetylated or underwent reaction, to give the desired glycosyl perbenzoylated derivatives, and a 2-acetamido or 2bromide I1 as a crystalline product with acceptable benzamido derivative results. Even labile N-substipurity without further recrystallization. The yields tuents may be difficult to remove when sensitive funcbased upon material reacted, varied between 65 and tions are introduced a t C-l.3 The second complicating 90%, the run described (76%) being typical. l'he factor arises from the readiness with which a 2-acylunchanged starting material could be recovered by filamido group interacts with the C-1 glycosyl halide tration and recycled in the reaction. Product I1 function, to give oxazoline4or oxazolidine5 type derivaappeared stable for a t least several weeks, if stored in a tivetx6 desiccator, and the stored material showed no change In the 2-amino-2-deoxy-~-galactose series, the fully in its infrared spectrum. The observed molecular roacetylated halides, 2-acetamid0-3,4,6-tri-O-acetyl-2-detation value of +71,200" is indicative of the CPD anooxy-a-D-galactopyranosyl bromide,' and chlorides have meric configuration. been reported; the present work describes the synthesis Compound I1 was treated with methanol in the of 3,4,6-tr~-0-acetyl-2-amino-2-deoxy-a-~-galactopypresence of silver carbonate to give methyl 3,4,6ranosyl bromide hydrobromide (II), a glycosyl halide tri-0 -acetyl- 2 -amino - 2 -deoxy-@-D - galactopyranoside derivative in which the amino group is unsubstituted. (111)as a sirup. Acetylation of I11 hydrobromide gave By analogy with the corresponding knowng D-glucose the known' crystalline methyl 2-acetamido-3,4,6-tri-Oderivative, compound I1 should undergo a wide range acetyl-2-deoxy-P-~-galactopyranoside (IV) ; this esof reactions leading to P-D-galactopyranosyl derivatives tablishes that I1 reacts with alcohols to give glycosides with an unsubstituted amino group a t C-2. of the p-D configuration. The D-glucose analog of I1 is prepared9 by heating 2-amino-2-deoxy-~-g~ucosehydrochloride with acetyl Experimental'2 bromide a t 70°, a procedure which is an adaptation of Department of Chemistry, The Ohio State University, Columbus 10, Ohio
(1) Supported b y Contract No. DA-49-193-MD-2143 (Research Foundation Project 1187) from the Walter Reed Army Institute of Reaearch, Washington, D. C . T h e opinions expressed In this article are those of the authors, a n d not necessarily those of the sponsoring agency. ( 2 ) L. J . Haynes a n d F. H . Newth, Adoan. Carbohydrate Chem., 10, 207 (19Ii5). (3) D. Horton a n d 11. I,. Wolfrom, J . O r g . Chem., 27, 1794 (1962). (4) F . Micheel. I?.-P. van d e Kamp, a n d H. Petersen. Ber.. 8 0 , 621 (1957): F. Micheel a n d H. Kocliling. ibid.. 91,673 (1958). (6) I?. Micheel a n d €1. Petersen, ibid.. 92. 298 (1959). (6) For reviews dealing with glycosyl halide derivatives of amino sugar see: A . 13. Foster a n d D. Horton, Aduan. Carbohydrate Chem.. 14, 213 (1959); 11. Horton. in "The Amino Sirears." R . W. Jeanloa a n d E . A . B:~lasa.Ed., Aradeinir Press, Inc.. New York, N . Y., 1963, in press. ( 7 ) Z. Tarasiejska a n d R. W. .leanlor, J . A m . Chem. S o c . , 80, 632.5 (19R8). (8) R . Heyworth, D. H. Leabark. a n d P. G. Walker, J . Chem. Soc., 4121 (1959).
(9) .J. C . Irvine, D. McNicoll, and A. Hynd. ibid.,99, 250 (1911).
3,4,6-Tri-O-acetyl-2-amino-2-deoxy-~-~-galactopyranosyl Bromide Hydrobromide (11).-A modification of the procedure (10) A . Col!ey, A n n . chim. Phyn., [ 4 ] 21, 363 (1870). (11) M. L. Wolfrom a n d T . hl. Shen H a n , J . Org. Chem., 26, 2145 (1961). (12) Melting points were determined with a Fisher-Johns apparatus and correspond to corrected melting ]joint. Si~ecificrotations were determined with a 4-dm. polarimeter tube, and o ~ t i c a lrotatory dispersion measure. ments were taken w i t h a Rudolph Model 260/655/81j0,'810-614 recording spertropolarimeter. Infrared spectra were determined with a PerkinElmer Infracord infrared spectrolhotometer. T h e 1~0tas3ium bromide pellets were pressed from a finely ground mixture of the dried sample with d r y analytical grade ~ ~ o t a s s i u nbromide. i Elemental microanalyses were made b y W . N. Rond. X - R a y powder diffraction d a t a : 'interplanar spacing. A., C u l i u radiation; relative intensity, estimated visually: 8 , stxona; m , medium; u , weak; v. very. Strongest lines are numbered in order of intensity ( I , stronaest): double numbers indicate ai)yroxinlately equal intensities. Thin layer chromatographic d a t a refer to separations made with silica gel G ( E . Merck. Darmstadt. Germany) activated a t 100°. Zones were detecte? with concentrated sulfuric acid.
3232
NOTES
VOL.28
used for the i)-gluco analog8J1 was used. 2-Amino-2-deoxy-a-~and the dried extract evaporated to a crystalline residue. Regalactose hydrochloridels ( I , 1.00 g.) was placed in a 25-ml. crystallization from methanol gave 1 V as large prisms; yield Erlenmeyer flask equipped with a Teflon-covered stirring bar and 200 mg. (55% calculated on 11), m.p. 212-216". A further rea drying tube, acetyl bromide ( 2 . 5 g., 5 mole equiv.) was added, crystallization gave analytically pure product; n1.p. 215-217', and the vigorously stirred mixture was heated slowly during 30 [ a ] % -15 f 1' ( c 1.5, chloroform); : : A: 3.03 m ( X H ) , 5.70 s min. to -55' (oil bath temperature). This temperature was (OAc), 6.03 s, 6.40 m (NHAc), 7.28 m (CHIC), 11.13 fi w maintained for 1 hr., during which time the mixture became red (axial H a t C-1); X-ray powder diffraction data1*: 13.27 s, 7.97 and slowly solidified. At this point the flask was cooled and was vs ( l , l ) , 7.38 vs (3), 6.92 m, 6.15 vs ( 2 ) , 5.5 w , 4.93 s, 4.57 m, connected to a water pump aspirator through a series of four %in. 4.37 m, 4.15 m, 3.95 vs ( 1, l ) , 3.75 8. U-tubes containing soda lime. After all the acid vapors were Anal. Calcd. for ClbH21S08: C, 49.84; H , 6.42; N, 3.87. absorbed (about 3 hr.), the residue was extracted with dry Found: C, 50.09; H , 6.44; N , 3.91. methylene chloride, the undissolved residue removed by filtration, The following constants have been recorded' for this compound, and the filtrate decolorized with activated carbon. Dry ether prepared by a different procedure: m.p. 216-217', [ a I z 3 ~ was added to the solution to the point, of incipient crystallization, -17 f 1" ( c 1.84, chloroform). and the mixture was refrigerated overnight to give I1 as pink plates, yield 900 mg. or 76% (range 6 5 4 0 % ) based on the amount of I which had undergone reaction, m.p. 144-148' dec., [ Q ] ~ ~+I60 D f 2" ( c 0.7, chloroform); specific optical rotatory The Chromous Chloride Reduction dispersion curve (c 0.34, 26') + l o 0 (700), +157 (600), +231 of Ergosterol Epidioxide' (5001, +403 (400), +574" (350 m r ) ; : : :A 5.74 vs (OAc), 6.11 w, 6.70 m ("I+), 7.34 m (CHIC), 11.80 w (equatorial H a t C - l ) , 13.45 p w (C-Br?); X-ray powder diffraction data12: MASATOTANABE A N D RAYMOND A . WALSH 12.96 vs (21, 8.76 w, 8.04 w, 6.03 vs ( l , l ) , 5.31 w, 4.33 vs ( l , l ) , 4.15 m, 4.04 s, 3.93 s, 3.58 w, 3.02 vs (3), 2.87 s. RecrystallizaLife Sciences Research, Stanford Research Institute, tion from methylene chloride and ether gave a less colored prodMenlo Park, California uct, but the melting point and specific rotation did not change significantly. Received June 24, 1963 Anal. Calcd. for C12H19Br.JO~: C, 32.09; H , 4.26; Br, 35.56; S , 3.12. Found: C, 32.01; H , 4.44; Br, 35.37; N , 3.12. The reduction of ascaridole (I) with ferrous ion is The methylene chloride-insoluble material was dissolved in reported to yieldI2besides ascaridole glycol, a mixture of aqueous ethanol (decolorizing carbon), and recovered by evaporatwo stereoisomeric hydroxy ketones I1 and 111. tion; yield, 400 mg. This material was treated with acetyl bromide as already described, end a further quantitypf I1 was isolated, in similar yield. When higher reaction temperatures were employed, the amount of methylene chloride-insoluble material remaining diminished, and was negligible when the reaction temperature was raised to 70". However, under these more vigorous conditions, the product was deep red in color, and required several recrystallizations for acceptable purity. Reaction a t room I I1 111 temperature for extended periods gave very little product. Efficient stirring was essential for success of the reaction. k'ormation of the isomeric ketones is thought to arise The bromo sugar I1 underwent no decomposition when stored in a desiccator for 6 weeks. The infrared spectrum of I1 was by one electron transfer from ferrous ion to the oxide very similar to that exhibited by the u-gluco analog. bridge, generating a tertiary alkoxy radical. The A crude product, m.p. 161', considered to contain 11, has alkoxy radical fragments to an a,p-unsaturated cyclobeen prepared by another route, l 4 biit no analytical or other hexenone and an isopropyl radical, followed by isophysical data were given. Methyl 3,4,6-Tri-0-acetyl-2-amino-2-deoxy-~-~-galactopyranpropyl radical attack on the 0-carbon of the cyclohexenoside (III).-A solution of the bromo sugar 11 (500 mg.) in dry one. Further electron and proton acquisitions yield methanol ( A tnl.) was shaken overnight with an excess of dry the observed products I1 and 111. silver carbonate and finely ground I>rierite.15 The mixture was To establish whether one-electron reduction by a filtered through Celite,lB and the filtrate evaporated to a colorless metal ion on ergosteryl acetate epidioxide (IV) would sirup which failed to crystallize. The product gave a positive ninhydrin reaction, migrated as a single zone ( R r = 0.75) on follow a similar reaction course and generate a steroidal thin layer vhromatograms with 8 : 1 : I benzene-methanol-pyrit-alkoxy radical, the reduction of IV was studied. dine as developer, and did not reduce Fehling solution. Treatment of epidioxide IV with chromous chloride3 Conversion of the I)roduct to the hydrobromide salt with an in ethanolic hydrochloric acid resulted in rapid reducequivalent of hydrogen bromide in methanol, followed by evapo2.97 s ( S H ) , 5.73 vs ration, gave a hygroscopic sirup, A::', tion. Chromatography of the materials formed yielded ( O A v ) , 6.12 w, 6.63 p w (XH3+). The product was not obtained ergosteryl acetate (V), a dimeric substance, CBoH~004 crystalline. (VI), and the hydroxy acetate (VII), all formed in equal Methyl 2-Acetamido-3,4,6-tri-0-acetyl-2-deoxy-~-~-galactoyields of about 30%. pyranoside (IV).--The sirully hydrobromide product from the The structures are assigned as follows. The dimer preceding preparation was dissolved in a cold mixture of dry pyridine ( 5 nil.) and acetic anhydride ( 2 . 5 ml.), and left for 3 hr. V I showed no selective ultraviolet absorption. Saponia t room temperature. The mixture was poured into water, fication of the dimer diacetate yielded a diol which difand the product was extracted with chloroform. The extract fered from the well known bisergostatrienol (IX),4the was washed with water, and the find traces of pyridine were product of photodimerization of ergosterol. The 1i.m.r. removed by shaking the extract with aqueous c~adniiiimchloride solution. The cadmium c*hloride-pyridine cmiplex was filtered, spectrum of the dimer VI indicated vinyl proton absorp(13) .\ product of I'fanstielrl Laboratories. Waukegan, Ill. T h e aiitliors tliank I h . I > . G. 1)olierty. of Oak Ridge National Laboratory. Oak Ridce, T e n n . . for a gift of tliis inaterial. (14) I
