PARALLEL AMIDEGROUPS
Nov. 5 , 1960
solution was diluted with aqueous sodium bicarbonate solution and extracted with chloroform. The crude product was isolated from the chloroform layer after washing with water, drying and concentrating. Two crystallizations from methanol afforded 88 mg. of 5a-methyl-androsta11e-17~-013-one (VII), m.p. 196-201', d 5 ~ 40' ( c 0.7, CHC1,); 2.92, 5.83 p : nuclear magnetic resonance infrared: A$:?' spectrum: the presence of three quaternary C-methyl groups is indicated. Anal. Calcd. for C2,,H1202: C, 78.89; H, 10.59. Found: C, 78.73; H,J0.79. A sample of VII, m.p. 201-202 , was obtained by recrystallization from methanol; [ a ] ~ 43', [Q]U)O +141', lalam +302O, [ala= +8;32", [aim + l l l O o , b l a o o +369', { a ] 2 e s -351' [ c 0.18, dioxane]. Chromatography of the mother liquors on 20 g. of basic alumina and elution with ether-petroleum ether (2 :8) followed by crystallization
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[CONTRIBUTION PROM THE
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from methanol afforded 50 mg. of a fraction, m.p. 203-204', presumably 5cr-methyl-androstane-l7,9-01. A sample for analysis was recrystallized from methanol, m.p. 204-207': 2.95-3.05 p. Anal. Calcd. for CpoH,,O: infrared: A$: C,82.69; €1, 11.80. Found: C, 82.54; H, 11.53. Further elution with ether-petroleum ether (8:2 and 9: 1) and crystallization from methanol yielded an additional 95 mg. of VII, m.p. 196-200°, a total of 183 mg. (60% yield).
5~-Methyl-androstane-l7~-ol-3-one Propionate (IX).-
Acylation of VI11 with propionic anhydride in pyridine a t room temperature overnight afforded 5a-methylandrostane17,9-ol-3-one propionate (IX). A sample for analysis was crystallized from methanol, m.p. 157-160°, a*% +32" (c 0.8, CHCL); infrared: Aig 5.77, 5.84 p. Anal. Calcd. for CuHssOi: C, 76.62; H, 10.07. Found: C, 76.25; H , 10.11.
DEPARTMENT OF CHEMISTRY, TRINITY COLLEGE, HARTFORD 6,
CONN.]
Parallel Amide G r o u p s 1 BY W. SCOTTWORRALL RECEIVED APRIL 1, 1960 The synthesis of the dilactam of cndo-cis-2,3-dicarboxy-en~~-cis-5,6-diaminonorbornane,which contains two amide groups held rigidly side by side in space, is described. This work is the beginning of a search for possible changes in the normal properties of functional groups due to intramolecular action of neighboring amide groups.
Functional groups, which participate in reactions catalyzed by proteolytic enzymes, during the reaction are probably in the more or less immediate neighborhood of amide groups, ie., peptide linkages. The phrase, functional groups, is intended to include both groups in the substrate molecules and groups in the protein enzyme. Therefore it is of interest to attempt to synthesize molecules in which various functional groups are held in well defined orientations with respect to one or more amide groups. A search can then be made for possible changes in the normal properties, e.g., nucleophilicity, of the functional groups. As the beginning of such a project a novel arrangement of two amide groups is speculatively presented in this paper and the synthesis is reported of a molecule containing this arrangement of amide groups. It is possible to imagine two planar2amide groups held rigidly side by side in space, ie., parallel amide groups, with the oxygen opposite the oxygen, and the nitrogen opposite the nitrogen, etc. (I). However, in this configuration the large dipoles associated with each amide groupa would oppose each other and, therefore, it is reasonable to assume that one of the amide groups would exist in the enolic form (11). I n this way the two dipoles would complement each other and conceivably would interact to form four regions of intense localized charge. Speculation in this area leads to the concept of a chemical reaction in which parallel amide groups participate by simultaneously giving and accepting a proton and, at the same time, the parallel amide groups are converted to their mirror (1) This work was presented a t the 136th Meeting of the American Chemical Societv, September, 1959, and was supported by a research grant, G-1951, from the National Science Foundation. (2) L. Pauling, R. B. Corey and H. R . Branacn, Proc. .%'all. Arad. Sci. (U.S.),37, 205 (1951); L. Pauling and R. B. Corey, %bid.,37, 272 (1951). (3) W. W. Bates and M. E. Hobbs. TEISJOURNAL, 73, 2151 (1951).
image, Le., II+III. I n this process the original quadrupole disappears in the transition state and then reappears in the reverse orientation. This intense reciprocating quadrupole hypothetically present in parallel amide groups is novel, and, therefore, the properties of parallel amide groups are of interest both with respect to the isolated structure and also with respect to any possible relationship with neighboring functional groups. It is con ceivable that such an arrangement, ;.e., parallel, of amide groups occurs in protein molecules. The dilactani of endo-cis-2,3-dicarboxy-endo-cis-5,6-diaminonorbornane (IV) contains parallel amide groups and the synthesis of this molecule is described in this paper.
I
I1
A
1v 1
I11
The carbon framework of norbomane was used as a rigid framework to which the paired amide groups were fastened. Treatment of endo-cis2,3-dicarboxy-exo-cis-5,Fi-dibromonorbornane anhydride' (V) with concentrated aqueous ammonia (4) J. A. Bersoo and R. Swidler. ibid., 76, 4060 (1954).
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Itr. SCOTT WORR.4LI.
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followed by passage of the product mixture through on heating gave the lactone-lactam X I as evidenced a strongly basic anion exchange resin gave a solid by mixed melting points and identical infrared (VI). When the solid VI was heated to about 185" spectra. This hydrogenation is another example a gas (basic to pH paper) was smoothly evolved to of exo addition. With respect to the solid VI: give a nicely crystalline compound (XI), m.p. because of the elemental analysis, conversion to the 192-192.5", which is considered to be the lactone- lactone-lactam X I , neutrality of an aqueous solulactam of endo-cis-2,3-dicarboxy-endo-5-amino-endo-tion, and successful passage through the strongly 6-hydroxynorbornane (XI) for the following reasons. basic ion exchange column, the solid is considered This structure is the only one which corresponds to be essentially endo-2-carboxy-endo-3-amidoto the requirements of the elemental analysis, the endo - 5 -hydroxy - endo - 6 - aminonorborane lactam. infrared spectrum, the neutrality of an aqueous However, the infrared spectrum of VI was similar solution, inertness to catalytic hydrogenation and but not identical to the spectrum of XIII. Fura plausible mechanistic route. An essential con- thermore, treatment of the lactone-lactam X I with sideration is the fact that the reaction is not of a concentrated aqueous ammonia gave a solid with type in which rearrangements of the norbornane an infrared spectrum identical to XIII. carbon framework have been found.5 It is not Low temperature recrystallization from water of known whether the lactam group is in the enol the carbonyl containing solid XI1 gave a solid with form as shown in the structural formula X I or is in a satisfactory elemental analysis, m.p. 232-234", the keto form although there are infrared bands and no change in the infrared spectrum, but rea t 6.04 and 6.19 p corresponding to the amide group. peated recrystallization of XI1 from hot water The band a t 6.04 p is expected for the amide group gave a solid (XIV), n1.p: 234-235.5", with apin the usual keto form, but the second band a t parently the same properties as XI1 in every way 6.19 I.( is ordinarily absent in cyclic secondary axn- including an essentially unchanged elemental ides6 The band a t 5.68 p is reasonable for the analysis except that there are two infrared bands lactone group.' in the carbonyl region a t 5.7 and 5.8 p . The Some information about the reaction path of the material used in the above hydrogenation was ammonolysis is provided by the fact that, when XIV. The solid XI1 was soluble in 5y0 sodium the reaction time was shortened, a relatively large hydroxide and acidification of the basic solution yield of endo-2-carboxy-endo-3-amido-exo-5-bromogave a precipitate with a spectrum identical to endo-6-hydroxynorbornane lactone (VII) could be that of XIV. With respect to the solids XI1 isolated. Evidence for the structure is the ele- and XIV: because of the elemental analyses, the mental analysis, and the infrared spectrum, 5.6: p conversion via hydrogenation to the lactone-lac(lactone) and 5.9 and 6.1 p (primary amide). tam X I , the infrared spectrum, conversion to an The amido-lactone VI1 rearranged very easily to oxime (vide infra), and the neutrality of the aqueendo- cis - 2,3 - dicarboxy - exo - 5 - bromo - endo - 6 - hy- ous solutions, a reasonable structure is endo-2droxynorbornane imide (VIII) either when heated carboxy-endo-3-amido-5-ketoendo - 6 - aminonorborvery briefly in water or when dissolved in dilute nane lactam. base and reprecipitated with acid. Evidence for Compound VI appears to be very similar to X I I I the structure of the dicarboximide VI11 is the and compound XI1 very similar to XIV. In brief, elemental analysis and the fact that the infrared the nature of the compounds VI, X I I , X I I I and spectrum in the carbonyl region, ;.e., bands a t XIV is clear in certain fundamental respects, but 5.6 and 5.8 I.(, are identical in wave length and the more intimate details remain unsettled. distinctive shape to the spectra of two norbornane Because of the number of functional groups concompounds (of fairly certain structure) with endo- centrated in a small volume, complications are not 2,3-dicarboximide groups. These compounds are surprising. The two carbonyl bands in XIV and endo-sis-2,3-dicarboxy-5-norborneneimide8 (IX) the base solubility of XI1 and XIV are of particular and endo-cis-2,3-dicarboxy-exo-5,6-epoxynorbornane interest; further experimental work is required to imide (X) which was prepared by oxidation of the choose from among various possible explanations. unsaturated imide I X with hydrogen peroxide. The solid XIV was converted to the correspondThe assignment of the exo configuration to the ing oxime XV with the loss of the carbonyl infrared epoxy group is by analogyg and from the general bands. Hydrogenation of the oxime (ex0 addition) view of exo addition.l0 with platinum gave (after drying in vacuo a t 100" Permanganate oxidation of the solid V I gave a for 3 hours) a nicely crystalline compound ( I V ) , new solid (XII) with a carbonyl peak a t 5.7 p m.p. 210.5-211'. The fact that compound I V which dissolved in water to give a neutral solution. is the dilactam of endo-cis-2,3-dicarboxy-endoHydrogenation of a variation of XI1 (vide infra) cis-5,6-diaminonorbornane is evidenced by the a t room temperature with platiriurii after the uptake elemental analysis, the absence of increased s o h of one mole of hydrogen gave a solid (XIII) which bility in dilute base or dilute acid, the neutrality of an aqueous solution, and the nature of the synthetic (5) For example, see H. Kwart and I,. Kaplan, THIS JIJLIRXAL, 76, route. Like the lactone-lactam X I it is not known 4078 (1954). (6) L. J. Bellamy, "The Infra-red Spectra of Complex Molecules." whether or not one of the lactam groups exists in John Wiley and Sons, Inc., N e w York, N. Y . , 1958, p. 217. the enolic form as shown in the structural formula. (7) J. A . Berson, T H I SJ O U R N A L , 76, 4975 (1954). (8) A. T. Blomquist and E. C. Winslow, J. Or&. Chent., 10, 149 ,4 possible complication was the fact that when (1945). the dilactam IV was isolated from an aqueous solu(9) J . A. Berson and S. Srizuki, T H I SJ O U R N A L . 80, 4341 (1958). tion a compound was obtained which lost a gas on (10) For other recent examples and references see S. J . Cristol a n d I
