J . Org. Chem., Vol. 43, N o . 7, 1978
Transalkylatiori of tert- Butyldiphenylmethanes ene, 54985-30-7; (E)-l-phenyl-4-hydroxy-l-hexene, 54985-35-2; tosylhydrazine, 1576-35-8; 3-methyl-2-butanone,563-80-4; pinacolone, 75-97-8; acetone, 67-64-1; 2-butanone, 78-93-3; cyclohexanone, 108-94-1; phenylacetone, 103-79-7; acetophenone, 98-86-2; cyclopentanone, 120-92-3; cyclopentanone tosylhydrazone, 17529-98-5; ethyl chloroformate, 541-41-3; (Z)-2-carboethoxycyclopentanone tosylhydrazone, 64884-90.8; (E)-2-carboethoxycyclopentanonetosylhydrazone, 64884-91-9.
References and Notes (1) For a review, see R. H. Shapiro, Org. React., 23, 405 (1976). (2) (a) K. J. Kolonko and R. H. Shapiro, J. Org. Chem., companion paper, this issue: (b) C. A. Bunnell and P. L. Fuchs, J. Am. Chem. SOC.,in press; (c) P. L. Fuchs, J. Org. Chem., 41, 2937 (1976); (d) S. D.Yound and W. T.
Burden, Tetrahedron Lett., 4019 (1976). (3) R. H. Shapiro, M. F. Lipton, K. J.Kolonko, R. A. Buswell, and L. A. Capuano, Tetrahedron Lett., 181 1 (1975). (4) J. E. Stemke and F. T. Bond, TetrahedronLett., 1815 (1975). (5) R. H. Shapiro and M. J. Heath, J. Am. Chem. Soc., 89, 5734 (1967). (6) R. H. Shapiro, Tetrahedron Lett., 345 (1968). (7) W. G.Kofron and M. K ‘feh, J Org. Chem., 41, 439 (1976).
(8) M. E. Jung, P. A. Blair, and J. A. Lowe, Tetrahedron Lett., 1439 (1976). (9) R. M. Sandifer, S. E. Davis, and C. F. Beam, Synth. Commun., 6, 339 (1976). (IO) R. H. Shapiro and T. Gadek, J. Org. Chem., 39, 3418 (1974). (11) E. Vedejs and W. T. Stolle, Tetrahedron Lett., 135 (1977). (12) F. E. Henoch, K. G. Hampton, and C. R. Hauser, J. Am. Chem. Soc., 91, 676 (1969). (13) F. N. Jones and C. R. Hauser, J. Org. Chem., 27, 701 (1962). (14) N. D. Epiotis, J. Am. Chem. SOC.,95, 3087 (1973). (15) W. C. Still andT. L. Mcdonald, J. Am. Chem. Soc., 96, 5561 (1974). (16) Due to solubility problems, the reaction was run at the elevated temperature. (17) G. J. Karabatosos and R. A. Taller, Tetrahedron, 24, 3347 (1968). (18) T. Ho and C. M. Wong, J. Org. Chem., 39, 3453 (1974). (19) G. Rosini, J. Org. Chem., 39, 3504 (1974). (20) A . Bahati, Chem. Commun., 476 (1965). (21) M. P. Dryfuss, J. Org. Chem., 28, 3269 (1963), and references cited therein. (22) E. J. Corey and M. F. Semmelhack, J. Am. Chem. Soc., 89, 2755 (1967). (23) J. A. Katzenellenbogen and R. S. Lenox, J. Org. Chem., 38, 326 (1973). (24) M. Naruse, K. Utimoto, and H. Nozaki, Tetrahedron Lett., 2741 (1973). (25) L. Friedman, R. L. Little, and W. R. Reichle, Org. Synth., 40, 93 (1960).
Studies on Selective Preparation of Aromatic Compounds. 15. The Lewis Acid Catalyzed Transalkylation of Some tert-Butyldiphenylmethanes and -ethanes in Aromatic Solvents’ Masashi Tashiro,* Takehiko Yamato, and Gouki Fukata Research lnstitute of Industrial Science, Kyushu University 86, Hakozaki, Higashz-ku, Fukuoka 812, Japan Received April 27, 1977
The Lewis acid catalyzed transalkylation of tert -butyl derivatives of diphenylmethanes (2a-f) and -ethanes (25a-g) in benzene or toluene was carried out under various conditions. It was found in the transalkylation of 2 that the AIC13-CH3N02 catalyzed transbenzylation with trans-tert -butylation was observed and the Tic14 transbenzylation of electron-rich tert -butyldiphenylmethanes having highly steric crowdedness such as 2,2’,6,6’-tetramethyl(2d) and 2,2’,3,3’-tetramethyldiphenylmethane(2f) took place without trans-tert-butylation. However, no AlC13CH3N02 catalyzed transalkylation of 25 was observed and only trans-tert-butylation in benzene took place to afford the desired 2,2’-dimethyl-(27b), 2,2’-diethyl-(27c), 2,2’-dimethoxy-(27d), 2,2’,3,3’-tetramethy1-(27e), and 2,2’,6,6’-tetramethyldiphenylethane(27f). Based on the above result it could be concluded that tert -butyl group can be used as a positional protective group for the preparation of some diphenylethanes but not diphenylmethanes,. Although AlC13-CH3N02 does not catalyze the transbenzylation and isomerization of diphenylmethanes,*-s it catalyzes transbenzylation of some 4,4’-dihydroxydiphenylmethane derivatives in toluene as was recently r e p ~ r t e d . ~ We undertook the present study to obtain more detailed information about factors influencing the above novel transbenzylation of diphenylmethanes and in general to gain a better understanding of the mechanism of transalkylation.
DCHLG 1
2a
Results and Discussion Preparation of Some tert-Butyldiphenylmethanes.The AlClS-CH3N02 catalyzed tert -butylation of diphenylmethane (1) with 2,6-di-tert-butyl-p-~resol~~ afforded 4,4’-di-tertbutyldiphenylmethane (2a) in good yield. 4,4’-Di-tertbutyl-2,2’-dimethyldiphenylmethane (2b) was prepared from 2a via 3. T h e chloromethylation of 4-tert-butyltoluene (4a) and 5-tert-butyl-1,3-dimethyl-(4b) and 4-tert-butyl-1,2dimethylbenzene (4c) afforded the corresponding 5-tertbutyl-2-methyl- (5a), 4-tert-butyl-2,6-dimethyl(5b), and 5-tert-hutyl-2,3-dimethylhenzyl chloride (5c), respectively, in good yields. In the Tic14 catalyzed benzylation of 4a, 4b, and 4c with the (Zc), 4,4’-dichlorides, 5,5’-di-tert-butyl-2,2’-dimethyltert-butyl-2,2’,6,6’-tetramethyl-(2d), 4,5’-di-tert-butyl0022-3263/78/1943-1413$01.00/0
1413
CH,C1
C!H?CI 3
LiAlH,-LiH”
in T H F
CHI 2b
C 1978 American Chemical Society
1414 J . Org. Chem., Vol. 43, No. 7, 1978
4-k
2,2’,3’,6-tetramethyl- (2e), and 5,5’-di-tert-butyl-2,2’,3,3’tetramethyldiphenylmethane (2f) were obtained in good
Scheme I
CH&l
CH30CH,C1
4a
Tashiro, Yamoto, and Fukata
-
yields (Scheme I). However, the expected product, 4-tert -butyl-2,6-dimethyldiphenylmethane (2g), in the benzylation of benzene with 5b was formed in only 43% yield with formation of 1,4-bis(4tert-butyl-2,6-dimethylbenzyl)benzene(6) in 50% yield even in excess benzene. The compounds 2g and 6 were also obtained by t h e Tic14 catalyzed benzylation of 4b with benzyl chloride (7a) and 1,4-bis(chloromethyl)benzene (8) in 93 and 60% yields, respectively. Transalkylation of 2. T h e Lewis acid catalyzed transalkylation of 2 was carried out under various conditions and the results are summarized in Table I. T h e tert-butyl group is transferred from 2a t o toluene.
4a, TiC1,
kCH+
in CS,
sa
2c CH&I I
+
2a
* l + $
AIC1,-CH3N0 in benzene
4b
in CS,
* C H 2 p ’CH, HJC’ 2d
CH
CH
H,C
CH ,
9a This result suggests that the trans-tert -butylation occurred selectively without the transbenzylation as expected from the previous papers.2-8 However, t h e AlC13-CH3N02 catalyzed transalkylation of 2b and 2c in benzene afforded %methyldiphenylmethane (10) and toluene (12a) besides the expected products 2,2’-dimethyldiphenylmethane(11) and tert -butylbenzene (9b). These results show clearly t h a t the transbenzylation and trans-tert -butylation of 2b and 2c took place simultaneously to afford 10 and 11. AlCl,-CH,NO,
2b-c
4
in benzene
2e
CH,OCH,Cl
4c
c
TiCl,, in CS,
+
+
t 2f
5c
CH, /
\
/
9b
CH, H,C
11 The latter compound 11 seems to be the intermediate in the formation of the former 10 and 12a. However, when 11 or 10 was treated under same conditions, only the starting compound 10 or 11 was recovered in quantitative yield. A1C13-CH3N0 in benzene
10
+
12a
I
+
E a
A1Cl3-CH3NO2
lo
H,C’
6
4b
+C
I C H 2 a % in CS, 2g 7a
4b
+ CICHI--@CH,CI 8
TiC1,
6
Ea
in benzene
Although intermediates 13 and 14 could not be isolated when 2b and 2c were transalkylated, the reaction pathways in Scheme I1 might be proposed. In fact, the A1C13-CH3N02 catalyzed reaction of 14b, which was prepared by the benzylation of 4a with 2-methylbenzyl chloride (7b), afforded 10 and 11 in 81.1 and 10.3% yields.
4a
+
&f 7b
CH?C1
TiC1, in CS2
14b
J . Org. Chem., Vol. 43, No. 7, 1978 1415
Transalkylation of tert- Butyldiphenylmethanes
Table I. The Lewis Acid Catalyzed Transalkylation of 2a
--
Run
Sub3trate
Catalystb
Solvent
Time, h
Product ( % ) c
1 2 3 4 5 6
2a 2a 2b 2b 2c 2c 2d 2d 2d 2d 2d 2d
A
Toluene Toluene Benzene Benzene Benzene Benzene Benzene Benzene To1u en e m -Xylene Toluene m-Xylene Benzene Benzene Benzene Benzene Benzene Benzene
3 3 0.5 3 0.5 3 3 3 2 0.5
1 (loo), 9a (100) No reaction 10 (75), 11 (25), 9b (1001, 12a ( 7 5 ) No reaction 10 (40), 11 (60), 9b (1001, 12a ( 7 5 ) No reaction 16 (80), 1 (20),9b (loo),12b (80) 2g (89),4b (77) 18 (93), 4b (95),9a (90) 19 (99),4b (90) No reaction No reaction 21 ( 7 3 ) ,2g (23),4b (70), 4c (30) 22 (75), 9b (80), 12b (78) 21 (20), 23 (40), 9a (38),4b (221, 1 ( + ) e 16 (88), 1 (12),9b(100) 11 (81), 10 (lo),9b (loo), 12a (10) 22 (97), 1 ( 3 ) ,9b (100)
I
8 9 10 11 12 13
B A B
A B A B B B C C B A B
2e
2f 2f 2g 14b 21
14
15d 16 17 18
A A A
3
5 3 3 3 1.5 1 1.5
A, AlC13-CH3N02; B, TiC14; C, SnC14. The a Reaction temperature, 50 "C; solvent/Z, 30 mol/l mol; catalyst/2,0.2 mol/l mol. yields were determined by GC analyses. 2f was recovered in 40%yield. e Plus sign (+) means a trace amount (
