July 20, 1959
SYNTHESIS O F
[CONTRIBUTION FROM THE
3667
~-BROMOBENZO [CIPHENANTHRENE
MCPHERSON CHEMISTRY LABORATORY O F THEOHIO STATE
USIVERSITY]
The Synthesis of 1-Bromobenzo[~Iphenanthrene~ BY MELVINS.NEWMAN AND DONALD K. PHIL LIPS^ RECEIVED JANUARY 17, 1959 The synthesis of 1-bromobenzo[c]phenanthrene starting from o-bromobenzaldehyde is described.
For many years, work in this Laboratory has had groups in various positions on these nuclei; and as a goal the synthesis of highly strained polycyclic second, the study of the effect of strain on the chemaromatic hydrocarbons. At first, the synthesis of ical properties of the functions involved. In this paper we report the synthesis of l-bromoa strained compound such as 4,5-dimethylphenanthrene (I) was of primary interest since difficulties benzo [clphenanthrene (XIV) by the sequence of met in attempts to prepare I led certain investiga- reactions outlined in the chart. This is the first tors3 to doubt that such a compound could be made. unambiguous synthesis of a highly strained polyHowever, the synthesis of 4,5-dimethyl~hrysene~cyclic aromatic compound containing a functional (11) showed that such strained compounds are group (bromine) on the nucleus.1° The bromine occupies the most crowded position possible in this capable of existence and synthesis. ring system. We hope to prepare other isomeric bromides and to compare their reactivities in reactions typical of aromatic bromo compounds. In the only reaction studied with XIV, the bromine atom was replaced readily by heating with cuprous I I1 cyanide in N-methyl-2-pyrrolidone to yield l-cyTheoretical interest in this type of hydrocarbon anobenzo [clphenanthrene in 71y0yield. Several points in connection with the synthesis was stimulated by the discoveries that 1,4,5-trimethyl-8-phenanthrylacetic acid5 (111) and 1- are noteworthy. Initially, o-bromobenzaldehyde methyl-4-benzo [clphenanthrylacetic acid6 (IV) was condensed with diethyl malonate to yield dicould be resolved. More stable (optically speak- ethyl o-bromobenzalmalonate in 88% yield. Howing) and more highly asymmetric examples of this ever, since conditions could not be found for the type of optically active molecule' have been found addition of phenylmagnesium bromide to this ester in 1,12-dimethyl-5-benzo[clphenanthrylacetic acid8 in high yield,s the route through the cyanoesters VI1 and VI11 was tried and found excellent as in (V) and hexaheliceneg another case.l' The product VI11 obtained was a C y 3 7% mixture of stereoisomers, which could be hydrolyzed to the malonic acid I X in good yield by long heating with 25% ethanolic potassium hydroxide. Attempts to hydrolyze VI11 by heating with 10% sodium hydroxide in ethylene glycol a t high tem111, [ a ] , 2 . 4 " IV, ["IB 2.1" peratures (170-185') were less successful in yielding I X as some decarboxylation occurred. The steps outlined in the chart were accomplished without undue difficulty until the reduction of XI1 to XIII. Although the reduction of XI1 by either lithium aluminum hydride, or by the Meerwein-Ponndorf-Verley method, yielded quantitaV, [aj,348" VI, la1,3707° tively material in which no carbonyl group was detectable by infrared spectral analysis, it was not There still remains much of interest to be done in possible to isolate by direct crystallization material this field and we are presently studying several as- which gave acceptable carbon-hydrogen analyses. pects. The research herein reported illustrates Furthermore, the products all melted over wide two areas: first, the synthesis of highly strained ranges. Attempts to obtain a crystalline dihydropolynuclear aromatic nuclei containing functional bromobenzo [clphenanthrene by dehydration of the crude diol mixtures were unsuccessful. However, (1) The work herein reported was supported in part by a grant from the Office of Ordnance Research and Development under contract treatment of the crude diol XI11 with iodine in xyNo. DA-33 019-ORD-1910, Project No. TB2-0001 (820). lene under reflux for very long periods of time (120 (2) This work is described in more detail in the Ph.D. Thesis of hours) afforded the aromatic bromo compound Donald K. Phillips, The Ohio State University, 1958. (3) See ref. 14 and 15 in ref. 4 following. S. Newman, TRISJOURNAL, 62, 2295 (1940); see also ref. 16-19 in this paper. ( 5 ) M. S. Newman and A. S. Hussey, ibid., 69, 978, 3023 (1947). (6) M. S Newman and W. B. Wheatley. ibid., 70, 1913 (1948). (7) This type of optical activity is termed "optical activity due t o intramolecular overcrowding"; see F. Bell and D. H. Waring, J. Chcm. SOC.,2689 (1949). (8) (a) M. S. Newman and R M. Wise, ibid., 78, 450 (1956); (b) M. S. Newman and M. Wolf, ibid., 74, 3225 (1952). (9) M. S. Newman and D Lednicer ,THISJ O U R N A L , 78. 4765 (1956). (4) M.
(10) (a) D. E. Adelson and h.1. T. Bogert, ibid., 69, 1776 (1937). claimed to have synthesized 1,2-dicarboxy-5-isopropyl-~-methylbenzo[clphenanthrene, hut this structure for their compound has been shown to be incorrect by L. V. Thoi and A. Belloc, Compt. rend., 239, 500 (1954). (b) The synthesis of 1-acetoxy-4-methylhenzo [clphenanthrene has been reported by C. Djerassi and T. T. Grossnickle, THIS JOURNAL, 76, 1741 (1954), but its structure has not been proved. (11) M. S. Newman and H. R. Flanagan, J . Ovg. Chem., 23, 796 (1958). (12) A pure sample was obtained by formation of the crystalline dicarbethoxy derivative and subsequent hydrolysis.
3GG8
hlELVIN
s. NEWMANAND DONALD K. PHILLIPS
Vol. 81
carbons, in this nitrile synthesis since cuprous cyanide is soluble in hot N-methyl-2-pyrrolidone.
+ CeH5MgBr
1%
NC
aBB FH
91%
/c\H
COOCzHs
NC
VI1
C00C2H5
1 CH2Nl u 2, LiAIH,
bH HOCH2 CHlOH
CH
X
HOOc/ O '\ H
1, CHJSOICl,CIH,N 2, KCN
IX
3, NaOH, 57'3 from HzO IX
polyphosphoric acid (66.72%)
*
HOOC ,C\H,COOH
XI1
AH2 CH2 XI
(54%)
XIV
E~perimental~~
o-Bromobenzaldehyde was prepared essentially as described for p-bromobenzaldehyde.20 Purification by means of the sodium bisulfite addition compound afforded obromobenzaldehyde, b.p. 100-104" (8-9 mm.), in 58% over-all yield. Diethyl o-Bromobenzalmalonate.-.4fter a solution of 180 g. of o-broinobenzaldehyde, 160 g. of diethyl malonate, 6 g. of benzoic acid, 7 ml. of piperidine and 500 ml. of benzene had been distilled into a column topped with a phaseseparating head for 19 hours (2 ml. of piperidine added after 11 hours), 17.5 ml. of water layer (9770) had accumulated. After an acid wash, the reaction mixture was treated in the usual manner. Distillation afforded 280 gd (887,) of diethyl o-bromobenzalmalonate, b.p. 178-181 at 1 mm. On triturating a small amount with Skellysolve F and recrystallizing from the same solvent, this bromoester was obtained as colorless crystals, m.p. 42.6-43.5' cor.; infrared absorption; 5.79(s) C=O, 6.10(s) C=C (KBr wafer). Anal. Calcd. for ClaHljOdBr: C , 51.4; H, 4.6; Br, 24.4. Found: C, 51.0; H , 4.7; Br,24.1. Ethyl o-Bromobenzalcyanoacetate (VII).--A reaction similar t o the above involving 168 g. of o-bromobenzaldehyde, 105 g. of ethyl cyanoacetate, 600 ml. of benzene, 1 g. of benzoic acid and 5 1111. of piperidine yielded 94% of the theoretical water after 7 hours. After the usual treatment 232 g. (91%). of VII, b.p. 148-150' (0.5 mm.), was obtained as a yellow oil which soou solidified. Recrystallization from Skellysolve C yielded colorless needles of V I I , m.p. 68 969.3", cor., infrared absorption, 4.53(w) CN, 5.75(s) C-0, 6.20(s) C=C (KBr wafer). Anal. Calcd. for Ci2H1002SBr: C , 51.4; H, 3.6; S , 5.0; Br, 28.5. Found: C, 51.2; H, 3.7; S , 4.9; Br, 28.1. o-Bromobenzalmalononitri1e.--.is above, refluxing of a solution of 20 g. of o-bromoberizaldehyde, 7.1 g. of malononitrile, 0.5 i d . of piperidine, 0.15 g. of benzoic acid and 300 ml. of benzene for 7 hours yielded 937, of the theoretical water. After the usual treatment the undistillod product was crystallized froin ethanol-water to yield 71'7, of dinitrile," m.p. 83-91"; iiifrared absorption, 4.5O(m) C.", 6.30-6.35(m-s) C=C (KBr wafer).22 This dinitrile is a
XIV directly in 54% yield.'3 This process is PUZzling since treatment of the non-crystalline residues from which XIV was obtained with dehydrogenating agents has not afforded further appreciable amounts of XIV. The yield of XIV from diol was sGnsitive to the amount of iodine used as well as the concentration of reactants and time of heating. The iodine cannot be the oxidizing agent as the optimal s t ~ ; ~ ~ ~ ~ (VIII).-To ~ ~ a well ~ concentration was far too low. stirred solution of 257 g. of VI1 in 550 ml. of benzene was That the compound XIV was in reality the fully added dropwise 989 nil. of 1.04 N phenylmagnesium brcaromatic compound was established by analyses of mide in ether with cooling t o keep the reaction mixture at XIV and of its 2,4,5,7-tetranitrofluorenone coII1- 20-25". After adding 102 ml. of benzene, solvent was distilled until the internal temperature was 60' (2 lir.). plex, by comparison of its ultraviolet absorption The liomugeiieous orange-red reaction mixture was held at spectrum with those of ben~o[c]phenanthrene~~ 00" (2 hr.), aiid then poured with stirring into 750 ml. of and l-methylbenzo [c]phenanthrene,lj and by n.- cold A' hydrochloric acid. After the usual treatment, distillation and redistil1atio:i yielded 298 g. (91%) of VI11 1n.r. spectroscopy.16 (197 g., b.p. 196-199" (0.5 mm.), and 102 g., b.p. 188-189" By heating a solution of XIV and an excess of at 0.2-0.3 mm.; infrared spectra of the two fractions of the dry cuprous cyanide in N-methyl-2-pyrroli- distillate were nearly identical so both fractions were comdone17 a t reflux (202') for one hour a 71y0 yield of bined). On standing the mixture of stereoisomers of VI11 Several recrystallizations of a portion from ~-cyanobenzo iclphenanthrene was obtained. The crystallized. . ~ _ _ _ use of N-methyl-2-pyrrolidone as a solvent in the (19) AII rueltiug points are uncorrected unless otherwise stated. Rosenmund-von Braun nitrile synthesis is to be All microanalyses by Galbraith Microanalytical Laboratories, Knoxville, Tenn. T h e term "treated in t h e usual manner" means t h a t an looked into further in view of previous observations ether-benzene sulutiou of the products was washed w i t h a saturated about this synthesis*'a ive hope to be solution of sodium chloride and then filtered through a layer of to determine the relative reactivity of the isomeric hydrous magnesium sulfate. T h e solvents then were r,,inovul bg disbromobenzo [clphenanthrenes, as well as bromo tillation undsr reduced p r e s u r e . Skellysolve F, b.p. 35-53', Skelly B, b p. 05-69", and Skellysolve C, h.p. 90-97', are aliphatiiderivatives of other strained polynuclear hydro- solve hydrocarbon solvents. All inirared absorption values are in F ; ( s ) = ail-
(13) Dr. M . Okawara (at O.S.U.) noted a similar formation of 5,8dimethylbenzo[c]phenanthrene on iodine-catalyzed dehydration of 5,s - dimethyl 5,8 dihydroxy 5,6,6a,7,8,12b hexahydrobenzo[c] phenanthrene, although in smaller yield. (14) hl. S.Xewman and Xi'. B. Lutz, THISJOURNAL, 78,2469 (1956). 3238 (1954). (15) G. hI. Badger and I. S. Walker, J. Che?n.SOC., (16) We thank Dr. George M. Slomp of the Upjohn Co., Kalamazoo, Mich., for this determination and analysis of the result,s. (17) We thank t h e Antara Chemicals Co. for a sample of N-methyl2-pyrrolidone. 1181 C F. Koclirh and A G. XVhitney, J . Or.? C h t , w , 6 , 795 (l!JiI).
-
-
-
-
strong, (m) = medium, i w ) = weak. (20) G. H. Colemau and G. E. Honeywell, "Org. Syntheses," Coll. 1'01. 11, John Wile? and Sons, Inc., New Yolk, N . Y..1943, p . 89 (21) H. G . S t u n and C. K . Noller, T R I RJ O U R N A L , 71, 2919 (194Y). give a m.p. of 90.0-90.5'. (22) X o t e t h a t replacement of carbetboxy by cyanu in the thre; analogous o-bromobenzal derivatives causes a shift toward l o n g a wave length of the C=C. absorption: compare with a similar scries in D. G . I . Felton a n d S F. D . Orr, J . C h e m . SOL.. 2170 (lQ55). ( 2 3 ) C u i n p a r c I3 D Corson m d I
