HYDROGENATION THE
PRESENCE
OF OF
SPIROCYCLIC
HOMOGENEOUS
N . V. S h u l y a k o v s k a y a , M. L. K h i d e k e l ' , and
L. 2. A.
COMPOUNDS RHODIUM
IN
CATALYSTS
V. V l a s o v a , Markushina
UDC 542.941.7:547.642
Spirans like 2-methoxy-l,6-dioxaspiro[4,4]nonane and 2-methoxy-l,6,9-trioxaspiro[4,5]decane possess considerable tranquilizing and antispasmodic action. Previously these compounds were obtained by the catalytic hydrogenation of the corresponding spirocyclic systems in the presence of heterogeneous catalysts like Raney nickel and nickel deposited on kieselguhr [1, 2]. Dependingon the conditions, the reaction went in two directions : A) reduction of the double bond in the furan ring with retention of the methoxy group; and B) cleavage of the methoxyl group as the result of hydrogenolysis, and reduction of the double bond in the ring
R ~ '~ cH,oD["o'~!
R F----I ,O--(CH)n--R'
(i)-(,v)
~
,O--{CH)~--R'
(V)-(VllI) (I), (V) R=R'----H, X=CH2, n = l; (II), (VI), R~H, R'=CHa, X=CH2, n = ~; (HI), (VII) R=R'=H, X=O, n = 2; (iV), (VIII) R=H, IV=OH3, X----O, n = 2 The p u r p o s e of the p r e s e n t p a p e r was to study the possibility of obtaining s a t u r a t e d s p i r o c y c i i c s y s t e m s employing homogeneous c a t a l y s t s , and to c o m p a r e the catalytic aetivity of homogeneous and h e t e r o geneous c a t a l y s t s . We employed t h r e e catalytically active c o m p l e x e s of rhodium: R h - f l u o r e s c e i n ( R h - F ) , R h - N - p h e n y i a n t h r a n i l i e acid ( R h - P A C ) , rhodium t r i s - t r i p h e n y t p h o s p h i n e chloride (RhCI(PPh3)3) , and the h e t e r o g e n e o u s c a t a l y s t Rh/A1203. EXPERIMENTAL
METHOD
The 2-methoxy- (1) and 2-methoxy-7-methyl-l,6-dioxaspiro[4,4]-3-nonenes(If) [1, 2], and the 2methoxy- (Ill) and 2-methoxy-2-methyl-l,6,9-trioxaspiro[4,5]-3-decenes(IV) [3], were obtained by the methods described in the literature. Rhodium tris-triphenylphosphine chloride and Rh-N-phenylanthranilic acid were synthesized as described in [3, 4], while Rh-fluorescein was synthesized as described in [4L Rh/AI203 was obtained as described in [5]. The reaction was run in a thermostatted glass hydrogenation flask at 20 ~ and with vigorous mixing. For the hydrogenation were used 2-3 mM of the substrate, 20 ml of solvent, and a catalyst contak~ing 3-4" 10-5 g-atom of Rh. The catalysts were analyzed by the TLC method. Aluminum oxide (If activity) was used as the sorbent, the system: hexane :ethyl acetate, 20 : 1 (for the spirononenes) and the system: hexane-ethyl acetate-benzene, 20 : 3 : 1 (for the spirodecenes), served as the eluant, and iodine was used as the developer.
....... ~nStitu{e of c h e m i c a l P h y s i c s , Academy of Sciences of the USSR. N. G. C h e r n y s h e v s k i i Saratov State University, T r a n s l a t e d f r o m [zvestiya Akademii Nauk SSSR, Seriya Khimieheskaya, No. 8, pp. 17991800, August, 1971. Original a r t i c l e submitted July 24, 1970.
9 1972 Consultants Bureau, a division of Plenum Publishing Corporation, 227 West 17th Street, New York, N. f. 10011. All rights reserved. This article cannot be reproduced for any purpose whatsoever without permission of the publisher. A copy of this article is available from the publisher for $15.00.
1689
TABLE 1 Hydrogenated compound
Catalyst, "cih, min (PPh,)aRhCI* Rh -- PAC "~ Rh--F I" Rh]AI20, :~
2 - Methoxy - I, 6 - diox aspiro [4. 4]-3-nonene (I)
4
24
5
21
2-Methoxy-7-methyl-l,6dioxaspiro[4. 4]-3-nonene (If)
5
25
5
23
2-Methoxy-l, 6, 9-trioxaspiro[4. 5]-3-deeene (Ill)
t01
t6
2
180
2- Methoxy-2- methyl-l, 6, 9trioxaspiro [4. 5]-3-decene (IVI
300
17
2
183
Hydrogenation product
2-Methoxy-1, 6-dioxaspiro' [4. 4] nonane (V) 2-Methoxy-7-methyl-I, 6dioxaspiro [4. 4] nonane(VI) 2- Methoxy-1, 6, 9, - trioxaspiro[4. 5] decane (VII) 2-Methoxy-2-methyl-1, 6, 9trioxaspiro [4. 5] deeane(~II)
*Absolute benzene used as solvent. I"Dimethylformamide used as solvent. $ Absolute ethanol used as solvent. DISCUSSION
OF R E S U L T S
As the e x p e r i m e n t s disclosed, all of the investigated rhodium complexes exhibited catalytic activity toward the spirans, but the activity varied. F r o m Table 1 it can be seen that the catalyst rhodium tris-triphenylphosphine chloride, which exhibited considerable activity in the hydr0genatton of spirononenes (I) and (II), proved to be less active in the case of the s p i r o d e c e n e s (III) and (IV). Apparently, this can be explained by the s t r u c t u r a l peculiarities of the spirodecenes, in whose molecule is present the dioxane ring. The most active and most universal catalyst for all of the spirans is R h - f t u o r e s c e i n . The hydrogenation rate of the investigated compounds (I)-(IV) on this catalyst is higher than t h e i r hydrogenation rate on the homogeneous catalysts R h - P A C and (RhCI(PPh3)3, as well as on the heterogeneous catalyst Rh/AL203. We will also mention that the hydrogenation of the spirans stops when the amount of absorbed h y d r o gen c o r r e s p o n d s to that calculated for the reduction of the C =C bond. An analysis of the composition of the catalyzates by the TLC method c o r r o b o r a t e d the fact that the phenomenon of hydrogenolysis and c l e a v age of the methoxyl group is not observed here. C ONC LUSIONS 1. The c o r r e s p o n d i n g saturated spirans are obtained in quantitative yield when methoxyspirononenes and methoxyspirodecenes are hydrogenated under mild conditions in the p r e s e n c e of homogeneous catalysts that a r e based on rhodium complexes. The cleavage of the methoxyl group was not observed. 2. The most effective catalyst for the hydrogenation of the investigated compounds is based on the complex of rhodium with fluorescein. LITERATURE 1.
2. 3. 4. 5.
1690
CITED
A. A. P o n o m a r e v and A. I. Markushina, Dokl. Akad. Nauk SSSR, 126, 99 (1959). A. A. P o n o m a r e v and I. A. Markushina, Zh. Obshch. Khim., 31, 554 (1961). J. A. Osborn, F. H. Jardine, J. F. Young, and G. Wilkinson, J. Chem. Soc., 1711 (1966). V. A. Avilov, M. L. K h i d e k e l ' , a n d E . G. Chepaikin, Authors' Application 1359338/23-4, March 18, 1970. M. L. K h i d e k e l ' , D i s s e r t a t i o n [in Russian], Moscow (1969).