212 SCHWEIZER, GREASY,LIGHT,AND
SHAFFER
tracted witjh two 50-ml portions of ether; the ether extracts were washed with two 100-ml portions of H20 and dried (MgS04). Rotary evaporation a t room temperature and analyses showed the benzoxepin 7 to benzopyran 8 ratio to be 98/2. C. With Sodium Ethoxide in Et0D.-Benzoxepin 7 (0.023 mol) was allowed t o reflux for 1 week in 7.6 ml of ethanol-d, with sodium ethoxide (0.008 mol) present. Work-up in the manner listed above in the previous experiment gave a 7/8 ratio of 83/17 (by vpc). The nmr spectrum of the mixture was a combination of the spectrum for 7 (with ratio of a/b/c/dl8 = 1/1/2/2) and 8 (ratio a/b/c/d'o = 1/1/1/2). Reaction 3-(o-Formylphenoxy)propyltriphenylphosphonium Bromide, 6 , with NaOCHa in CH10D.--8alt 6 (6.9 g, 0.014 mol) was added to a solution of 0.014 mol of NaOCHa in 20 g of CHdOD and allowed to reflux for 2.5 hr. The solvent was stripped and the residue Rhort-path distilled (0.3 mm) to give 0.6 g (30%) nmr (neat) 6 1.30 (d, 2, of 2-methyl-ZH-l-benzopyran-a,3-d~: J o d = 7 Hz), 4.90 (broad triplet, 1, Ho), 6.30 (9, 1, Ha), 6.777.42 ppm (broad m, 4, aromatic). Reactions of Cyclopropyltriphenylphosphonium Bromide, 12. A.-Salts 1 and 12, and NaOCHa, in equimolar (0.0078 mol) ratios, were allowed to reflux in 50 ml of absolute ethanol for 8 days. Concentration and vpc of the crude mixture showed peaks in the areas (checked by spiking experiments) expected for 7 and 8 in approximately equal amounts with an over-all yield of less than 1%. B.-Similar experiments were run with only 1 and 12 [or 1, 12, and a catalytic amount of NaOCH3 (0.0008 mol)] with no apparent reaction to make 7 and 8 observed. 3-(p-Formylphenoxy)propylBromide, 19.-The title compound, 19, was prepared in exactly the same manner as that reported above for 3 (except for the use of p-hydroxybenzaldehyde). After stripping the chloroform, 132 g (3801,) of 3-(p-formylphenoxy)propyl bromide, 19, was obtained: bp 135' (0.15 mm); nz4D1.5820; ir (neat) 3000 w, 2875 w, 1700 S, I610 S, 1520 s, 1180 s, 1025 s, 930 m, 835 s; nmr (cc14)6 2.37 (quintet, 2, Hz), 3.77 (t, 2, H, J i , z = 7 Hz), 4.35 (t, 2, Hi, J2,3 = 7 Hz), 7.35 (d, 2, Haptho, J o , m = 9 Hz), 8.20 (d, 2, Hms~atJ o , m = 9 Hz), 10.02 ppm (s, 1, CHO). Anal. Calcd for ClaH11BrOz: C, 49.70; 13, 4.46; Br, 32.77. Found: C, 49.67; H, 4.49; Br, 32.98. 3-(p-Formylphenoxy)propyltriphenylphosphoniumBromide, 20. -Triphenylphosphine, 5 (103 g, 0.4 mol), and bromide 19 (97 g, 0.4 mol) were allowed to reflux for 24 hr in 400 ml of dry ethyl acetate, then cooled with stirring another 24 hr. Filtration
The Journal of Organic Chemistq and stirring (of residue) in hot ethyl acetate (24 hr), filtration, and washing and drying of the residue gave 117 g (58%) of 20. Recrystallization from acetone gave an analytically pure sample: mp 140-141'; ir (KBr) 3030 w, 2900 w, 1680 s, 1600 s, 1500 m, 1440 s, 1260 s, 1220s, 850 m, 742 s, 720 s, 690 s; nmr (CDCld 6 2.2 (broad, 2, Hz), 4 (broad, 2, HI), 4.52 (broad t, 2, Ha), 7.09 (d, 2, Hortho,Jo,m= 9 Hz), 7.65-8.25 (broad, 17, aromatic), 9.87 ppm (2, I, -CHO). Anal. Calcd for CzsHzeBrOnP: C, 66.63; H, 5.20. Found: C, 65.77; H, 5.64. Reaction of 1-(p-Formy1phenoxy)propyltriphenylphosphoniUm Bromide, 20, and Sodium Ethoxide in Ethanol.-Salt 20 (10.1 g, 0.02 mol) was allowed to reflux (24 hr) in a solution of sodium ethoxide (0.02 mol) in ethanol (50 ml). The mixture was carefully acidified with gaseous HBr and filtered; the residue was washeduntil the wash water gave a negative halogentest (AgN03). Concentration of the original mother liquors and crystallization from hexane gave 4 g (727,) of triphenylphosphine oxide (meltmg point and mixture melting point checked with an authentic sample). The halogen-free residue from the water wash, after washing with ethanol and drying, gave 2.9 g (98%) of a yellow solid, mp 130-135". Crystallizatlon from dimethylformamide gave a sample: mp 128-130; ir (KBr) 2080 w, 2980 w, 1620 3, 1550 s, 1520 s, 1450 m, 1243 S , 1035 s , 970 s, 843 m; nmr (pyridine-&) 6 2.58 (broad m, 2, -CHzCH=), 4.05 (broad t , 2, -OCH2-, J = 6 Hz), 6.2-7.0 (broad m, 2, ==CHAr),7.0-7.6 ppm (broad, 4,aromatic). A correct analysis was obtained for the following structlire: OCHC6HdOCHzCHsCH[=CRCsHaOCHzCH&H] F=CHC~&OC H ~ ~ H ~ C H S P O ( C 21. ~H~)Z, Anal. Calcd for CllzH111012P:C, 79.99; H, 6.67. Found: C, 80.15; H , 6.73.
Registry No.-3, 17954-11-9; 4, 17954-12-0; 6, 17954-76-6; 7, 14949-49-6; 8, 2513-24-8; 9, 6169-78-4; 10, 13030-26-7; 19, 17954-81-3; 20, 17954-82-4; 21, 17954-83-5. Acknowledgment.-This work was supported by Grant PRF2032-A1 from the Petroleum Research Fund of the American Chemical Society. E. E. S. and C. J. B. gratefully acknowledge this support.
Reactions of Phosphorus Compounds. XX. Reactions of Furfuryl-, Dihydrofurfuryl-, a n d Tetrahydrofurfuryltriphenylphosphonium Bromide E. E. SCHWEIZER, W. S. CREASY,K. ICII), 3.95-3.50 (9, 2, -CHzO-), I .93-1.45 ppm (m, 3, -CHzCHD-). Reaction of Methoxyethyltriphenylphosphonium Bromide, 13, with Benzaldehyde.-To 100 ml of absolute ethanol was added 0.3 g of S a , under nitrogen. When this had dissolved, 7.6 g (0.018 mol) of 13* was added and stirred under reflux for 6 hr. Then 2.2 g of benzaldehyde (0.02 mol) was added; the mixture, refluxed under nitrogen an additional 12 hr, was added to 500 ml of water, extracted with two 200-ml portions of ether, dried (MgS04j, and concentrated. This was then short-path distilled t o give ethyl cinnamyl ether ( 0 3 g), 14, as the sole Wittig product. The yield was 19% (along with 427, of benzyl alcohol). The product was identified by its nrnr spectrum and by comparison of its vpc retention time with that of an authentic sample. Y o methyl cinnamyl ether could be detected in the vpc of the product mixture by comparison with an authentic sample. Furfuryltriphenylphosphonium Bromide, 16.-To a 500-ml round-bottomed flask fitted with condenser and stirrer was added 20 g (0.204 mol) of fresh furfuryl alcohol in 200 ml of ether (dried over Na). To this was added dropwise with stirring and ice-bath conditions 20 g of phosphorous tribromide in 30 ml of dry ether. The total addition took 0.5 hr. The ice bath was then removed, the mixture stirred for several moments, and allowed to stand at room temperature for l hr. The ether was decanted into a clean flask, treated (with cooling) with a 407, NaOH solution, and stirred for 10 min. The ether was decanted off again and dried over XaOH pellets. After filtration, the ether solution of the bromide was added to a 1-1. flask and treated with 53 g (0.204 mol) of triphenylphosphine in 400 ml of ether (under Nz). The triphenylphosphine solution was added dropwise over a period of 0.6 hr. The temperature was brought to reflux and held for 48 hr, at which time the reaction was stopped and the salt filtered to give 57 g (667,) of 16: mp 269-271" dec; ir v (Nujol) 1590, 1370, 1150, 1100, 970, 755, 740, 730, 690 ern-'; nmr 6 (CDCl3) 5.60 (d, 2, CHZ), 6.30 (m, 1, =CI-I), 6.55 (t, 1, =CH), 7.35 (m, 1, =CH), 7.75 ppm (m, 15, C6Hs). Anal. Calcd for Cz3HzoBrOP:C, 65.26; H, 4.76; P , 7.32; Br, 18.88. Found: C, 65.55; H , 4.73; P , 7.48; Br, 18.66. 2-Styrylfuran, 17a and 17b.-To a 500-ml round-bottomed flask fitted with condenser and stirrer was added 10 g (0.024 mol) of 16 in 200 ml of DMF. To this was added, under Nz,1.1 g (0.024 mol) of a 54y0 dispersion of NaH. As soon as the red ylide color formed, 2.52 g (0.024 mol) of benzaldehyde in 100 ml of DMF was added dropwise to the reaction mixture and the temperature brought to 110' and held for 48 hr. The reaction added to 11. of water, extracted, washed, and mixture was '&-*I dried in the above manner. The ether was then concentrated and short-path distilled under vacuum to give 3.9 g (9570 yield) of products. This was shown to be two products, by vpc, in the ratio of 37/63 cis/lyans isomer. These isomers were separated by vacuum distillation. cis-2-Styrylfuran, 17a, showed the following characteristics: bp 79-80' (0.5 mm); ~ Z Z D 1.6215; ir v 3190, 1600, 1480, 1440, 1010, 880, 840, 740, 695 Gin-'; nmr 6 (neat) 5.40-5.85 (m, 5, =CH), 6.50-7.10 ppm (m, 6, C&); A":?: 303 mfi (emax 14,000).
Anal. Calcd for CIZHIOO:C, 84.68; H, 5.92. Found: C, 84.64; H, 6.05. trans-2-Styrylfuran, 17b, showed the following characteristics: bp 89' (0.5 mm); mp 49-50' (CH80H) [lit.'6 mp 49-51'; bp 150-165 (3 mm)]; ir v (neat 1600, 1380, 1160, 1020, 960, 800, 740, 690 cm-1; nmr 6 (DCC13) 6.35 (m, 3, =CH), 6.90 318 mp (emax 32,000). (m, 2, =CH) 7.35 ppm (m, 5, C6&); ": : A: 2-(p-Phenylethyl)tetrahydrofuran 5a via Hydrogenation of 17a and 17b.-A mixture of 17a and 17b, 1.7 g (0.01 mol), was dissolved in 50 ml of methanol and shaken in a hydrogen atmosphere over 10% Pd-C catalyst for 4 hr, a t which time the reaction was stopped, filtered, concentrated, and short-path distilled, under vacuum, to give 1.4 g (81% yield) of a product whose infrared spectrum was identical with that of 2-(p-phenylethyl)tetrahydrofuran (5d). Furfurylidenecyclohexane, 18.-To a 600-ml round-bottomed flask fitted with condenser and stirrer was added 10 g (0.024 mol) of 16 in 150 ml of DMF. To this was added, under XZ, 1.1 g (0.024 mol) of a 54% NaH dispersion. As soon as the red ylide color formed, 2.3 g (0.024 mol) of cyclohexanone in 100 ml of D M F was added dropwise to the reaction mixture and the temperature raised to 110' for 48 hr. Then the D M F solution was added to 1 1. of HzO and worked up in the above manner. The ether was Concentrated and short-path distilled under vacuum to give 2.05 g (54% yield) of the product, 18. The product was distillcd again to purify: bp 51-32' (0.30 mm); nzGD1.5451; ir v (neat) 2950, 2850, 1650, 1440, 1145, 1010, 840, 725 cm-'; nmr 6 (neat) 1.25 (m, CHZ),1.85 (m, 2, CHZ),2.30 (m, 2, CHz), 269 mp 5.6-6.0 (m, 3, =CH), 6.9 ppm (d, 1, =CH); ": : A: (emax 17,300). Anal. Calcd for Cl1HilO: C, 81.44; H , 8.70. Found: C, 81.26; H, 8.59. 2-(Cyclohexylmethy1)tetrahydrofuran.-A sample of 18 (I g, 0.006 mol) was dissolved in 50 ml of methanol and shaken in a hydrogen atmosphere over 10% Pd-C catalyst. After 85% of the theoretical amount of hydrogen had been consumed (3 hr), the reaction was stopped, filtered, and concentrated. Distillation under vacuum gave 0.8 g (78% yield) of 5c: bp 45" (0.1 mm); n Z o1.471 ~ (lit." nzoD1.469); ir v (neat) 2950, 2850, 1420, 1060, 1000, 980, 810 em-'; nmr 6 (neat) 0.81-2.50 (m, 17, CHz and CS-I), 3.50-4.50 ppm (m, 3, CHZand CH). 4,5-DihydrofurfuryltriphenylphosphoniumBromide, 2 1.-To a 250-ml, three-necked, round-bottomed flask fitted with stirrer and condenser was added 12 g (0.14 mol) of 2-methyl-4,5-dihydrofuran13 in 100 ml of benzene. To this was added portionwise, keeping the temperature below 35', 25 g (0.14 mol) of Nbromosuccinimide ; the mixture stirred at room temperature for 0.5 hr, then cooled to lo', and filtered. The benzene solution was then added to a 1-1. flask, diluted with400 ml of ethyl acetate, and treated (under No) with 35 g (0.14 mol) of triphenylphosphine in 1,50 ml of ethyl acetate. The temperature was brought to 60' and held for 24 hr. Filtration gave 7.1 g (15% yield over both steps) of 21: mp 246-247" dec; ir v (KBr) 3000, 2950, 1620, 1490, 1440, 1180, 1150, 1110, 1030, 1000, 970, 940, 905, 885, 750, 725, 695 crn-1; nmr 6 (DCCh) 2.35 (m, 2, CHZ),3.40 (m, 2, CHz), 4.50 (t, 2, CIL), 5.65 (d, 1, =CH), 7.75 ppm (m, 15, CeHs ). Anal. Calcd for CzsHzzBrOP: C, 64.95; H, 5.21; Br, 18.79; P, 7.28. Found: C, 65.04; H , 5.28; Br, 18.90; P, 7.51. Isolation of 17a and 17b via Reaction of 21 with Benzaldehyde. -To a 251-ml round-bottomed flask was added 2.7 g (0.006 mol) of 21 in 150 ml of DMF. This was treated with 0.4 g (0.006 mol) of a 54% NaH dispersion under Nz. As the red ylide color formed, 0.68 g (0.006 mol) of benzaldehyde in 50 ml of D M F was added dropwise and the temperature brought to 110" for 48 hr. The reaction was then stopped and worked up in the previous manner. The concentrated ether solutjon was shortpath distilled to give 0.40 g (37% yield) of two products by glpc in the ratio of 39/61 17a/17b. The two were separated by vacuum distillation to give samples whose infrared spectra were identical with those of 17a and 17b. Isolation of 5a via Reaction of 21.-A sample (1 g, 0.006 mol) of 17a and 17b obtained by the reaction of 21 with benzaldehyde as shown above was hydrogenated in the usual manner to give a 70% yield of 5a, as shown by its glpc retention time and infrared spectrum. (16) R. B. Woodward, J. Amer. Chem. SOC.;62, 1478 (1940). (17) V. G. Bukharov and T. E. Pozdnyakova, Izv. Akad. Naulc SSSR, Otd. Khim. N w ~ k 136 , (1961).
218 NOTES
The Journal of Organic Chemistry
Isolation of 16 via NBS Bromination of 2-Methyl-4,s-dihydrofuran with Peroxide.-To a 600-ml flask fitted with stirrer and condenser was added 25 g (0,03 mol) of 2-methyl-4,5-dihydrofuran in 200 ml of benzene. To this was added a small amount of benzoyl peroxide and then, with stirring, 53 g (0.3 mol) of N-bromosuccinimide (NBS) slowly, keeping the temperature below 35'. After stirring for 1 hr at room temperature, the mixture was cooled to lo", filtered, diluted to 600 ml with ethyl acetate in a 1-1. flask, and treated with 79 g of triphenylphosphine in 200 ml of ethyl acetate, dropwise. The temperature was then brought to reflux and held for 24 hr. Filtration gave a solid which had mp 270-271' dec and was shown to be 16 by its infrared spectrum, tlc, and mixture melting point. Hydrolysis of 21.-To a 250-ml flask fitted with stirrer and reflux condenser was added 7.0 g (0.017 mol) of 21 in 100 ml of aqueous ethanol. T o this was added 0.9 g (0.017 mol) of KOH in aqueous ethanol. The mixture was refluxed for 12 hr, added to 500 ml of HzO, and extracted with ether. The ether wm
washed, dried, and concentrated to give a 1.1 g (65% yield) of a mixture of 15,435 2-methy1-4,6-dihydrofuran and 2-methylfuranI respectively, as shown by vpc.
Registry No.-3, 15138-76-6; 4a, 1S138-77-7; 18138-78-8; 4c, 18138-79-9; Ja, 2429-96-1; 18138-81-3; 9d, 15138-82-4; 9e, 18138-53.5; 2430-16-2; 11, 18138-55-7; 16, 18138-86-8; 18138-87-9; 18, 15138-38-0; 21, 18153-52-1.
410, 9c,
loa, 17a,
Acknowledgment.-This work was supported, in part, by a grant (PRF 2032-A1) from the Petroleum Research Fund of the American Chemical Society, by B Public Health Service Predoctoral Fellowship (to E. T. Shaffer), and by a Public Health Service Grant (9R01 CA 11000-04) for which we are most grateful.
Notes Bridged Ring Compounds. XVI,' Stereoselectivity in Epoxidation of Bicyclic Anhydrides2 L. H. ZALKOWAND S. K. GABRIEL School qf Chemistrg, Georgia Institute of Technology, Atlanta, Georgia 9033R Received June 24, 1968
Recently, we reported that, both on ozonlysis and on treatment with trifluoroperacetic acid, methyl maleopimarate gave the sun-epoxide La It was suggested that the stereospecificity observed might be due to
and imides are reported to yield exclusivelg exo-epoxide~.~~~ I n order to obtain more information regarding intramolecular epoxidations we decided to study the epoxidation of bicyclo [2,2.2]-5-octene-2,3-endo,cis-dicarboxylic anhydride (111). During the course of our investigation, Fray, et al.,' reported that epoxidation of 111 paralleled that of bicyclo L2.2.1]-5-heptene-2,3-endo1cis-dicarboxylic anhydride; that is, the ezo-epoxide was exclusively obtained (p attack). On the other hand, anhydride IV gave the endo-epoxide (a attack). Fray, et therefore, concluded that the stereochemistry of epoxidation of these cyclic compounds is determined solely on steric grounds.
-4 I11
I
I1
formation of an intermediate cyclic peroxide, followed by intramolecular epoxidation. Such an explanation was first proposed by Henbest4 for the cis epoxidation of cis-A4-tetrahydrophthalic anhydride. However, others6 have argued that in the latter case the observed stereospecificity arises because the cyclohexene ring in cis-A4-tetrahydrophthalic anhydride exists as an "equatorial half-boat" (11) and exo attack occurs just as in norbornenyl anhydrides. Norbornenyl anhydrides (1) Bridged Ring Compounds. XV: R. L.Hale a n d L. H. Zalkow, Tetrahedron, in press. (2) Presented a t the 19th Southeastern Regional Meeting of the American Chemical Society, Nov 1-3, 1967, Atlanta, Ga. (3) L. H. Zalkom, & V.'IKulkami, . and N. N. Girotra, J . Org. Chem., 80, 1679 (1965). (4) H. B. Henbest, Proc. Chem. Soo., 169 (1963) (5) A. P. Gray and D. E. Heitmeier, J . OW. Ch.snz., 30, 1226 (1965).
1v
V
We have found that epoxidation of 111 under conditions similar to those reported by Fray7 does in fact yield appreciable amounts of the endo-epoxide (Table I). Fray, et ul,,7 isolated the exo-epoxide of I11 in 48% yield by crystallization and apparently did not account for the remaining products.
VI
VI1
VI11
All of the products mentioned in Table I were isolated in pure form and analytical and spectral data support (6) J. A. Berson and 8. Suzuki, J . Amer. Chem. Soc., 80, 4341 (1958). (7) G. I. Fray, R. J. Hiton,and J. M. Teire, J . Chsm. Soc., C,592 (1966).
