NEGATIVE-ION
MASS
SPECTROMETRY
AND
STEREOCHEMISTRY
OF
6.
3,7,11-TRIMETHYL-2,6,10-DODECATRIENE-
AND
ESTERS
OF ISOMERIC
ORGANIC
COMPOUNDS
10-OXO-3,7-DIMETHYL-2,6-DECADIENECARBOXYLIC
ACIDS
I. I. Furlei, V. N. Odinokov, V. I. Khvostenko, G. A. Tolstikov, N. Ya. Grigor'eva, I. M. Avrutov, and A. V. Semenovskii*
UDC 543.51:541.63:547.481
We have a l r e a d y d e m o n s t r a t e d the potential utility of negative-ion mass s p e c t r o m e t r y for solving s t e r e o chemical problems [1-4]. We have continued this work examining the fragmentation of ethyl 3, 7 , 1 1 - t r i m e t h y l 2 , 6 , 1 0 - d o d e c a t r i e n e c a r b o x y l a t e s (farnesyl esters) (Ia-d) and the products of t h e i r ozonolysis at the t e r m i n a l double bond (IIa-d) [5, 6] with the intention of getting information on the effect of the double-bond g e o m e t r y on
the nature of the negative-ion mass spectra I
I
I
o
I I i ,-~/~./%/~/
H
/%/~,'%/~/%/~o/~
otl
(Ia)
L
(Ib)
I
0
J.
,'~/~/=x/~,,,/~oH ~ / I
I
0
]
lj
/~/'/=x/Lx-T-"--\o/~
(Ic) 0
o ~/
(Id) 0 tl
0
J
I
0 0
(IIa) o
l
% / \ / = ~ / ~ ' ~ / Iit o (II c)
(IIb) o
o
"x/
I
0 IF
%,'\/=~,,~1--~/\o/~ (lid)
We r e c o r d e d the m a s s s p e c t r a and plots of the effective negative-ion (NI) yield on an MKh-1303 adapted for the m e a s u r e m e n t of NI c u r r e n t s . The e l e c t r o n e n e r g y s c a l e was calibrated f r o m the yield of SF 6 ions f r o m S F6. The figures of Table 1 show that the NI mass s p e c t r a of the g e o m e t r i c a l i s o m e r s a r e s i m i l a r and differ only in the relative intensity of the peaks of the individual ions. The formation of the NI's can be accounted for by e l e c t r o n capture in the orbitals of the e s t e r group followed by fragmentation by simple cleavage of the bonds f o r m i n g ions with m / e 263, 235, 127, 55, 45, and 43 (farnesyl esters) o r m / e 237, 209, 127, 55, 45, and 43 (oxo e s t e r s ) . M o r e o v e r the s p e c t r a of compounds (Ia-d) and (IIa-d) show ions with m / e 217 and 191 r e s p e c tively, f o r m e d b y a m o r e complex route by elimination of EtOH f r o m the ( M - H ) - ions. In the case of the oxo e s t e r s (IIa-d) the m a s s s p e c t r a reveal a m e t a s t a b l e ion with m / e 153.5, c o r r e s p o n d i n g to the decomposition p r o c e s s m / e 237 ~ m / e 191 + 46. The C2 and C4 H atoms s e e m to be involved in the f o r m a t i o n of the ions with m / e 217 and 191, as in the fragmentation of the NI's of e s t e r s of unsaturated acids [7]. This suggests the s t r u c t u r e RC ~-~ CO- for these * Deceased. Institute of Chemistry, Bashkir Branch of the Academy of Sciences of the USSR, Ufa. S. D. Zelinskii Institute of Organic Chemistry, Academy of Sciences of the USSR, Moscow. Translated from Izvestiya Akaderail Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 330-335, February, 1981. Original article submitted April 17, 1980. 254
0568-5230/81/3002-0254507.50 9 1981 Plenum Publishing C o r p o r a t i o n
b0
-
4t
HC~-C-O-
43
45
CzH~0-
55
81
95
t63 (M-II-C2H~OH-OCHCH= CH2) t35 127
(M-H-CzHsOH-C0)
t4 (8,2)
26 (8,2) t9 (8,2)
13
(s,2)
6
(8,2) t4 (5,0) 32 (9,4) (7,o) 2,5 (9,0) 70 (6,2) 32 (8,4) t0 (8,2)
21 (4,8) loo (9,o) tl
t8 (4,8) 80 (9,0) 4 (8,2) 26 (5,0) 46 (9,4) 28 (7,0) 1I (9,0) 85 (6,2) 23 (8,4) t0 (a~2) tl,7 (4,8) t00 (9,0) 6 (8,2) to (5,0) 30 (9,4) 6 (7,0) 4,5 (9,0) 77 (6,2) 30 (8,4)
2t (8,2)
t2 (5,0), 30 (9,4) 12 (7,0) 7 (%0) t00 (6,2) 20 (8,4) 15 (a~2)
20 (4,8) t00 (9,0) 5 (8,2)
(8,6)
15,5
23 (6,8) 4I (8,9) t5,5 (5,6) t00 (8,6)
t9 (5,6) 49 (9,4) 3 (8,6)
(9,0) 23 (4,7) 77 (8,9), 5 (8,4)
8
(6,9) 3 (9,0)
8
t00 (8,2)
10O (8,2)
82,5
t00 (8,2)
(M-H-C~.HsOH) 217(I), i9t(II), (8,2)
49 (8,0) 42 (3,8) 9t (9,1)
(M-H) 263(I), 237 (II) (M-C2Hs) -
-
t8 (6,8) t6,5 (3,8) 23 (6,8) 50 (9,5) 23 (6,8) 28 (8,3)
39 ca,o) 49 (3,8) 85 (9,1)
t7,5 (8,0) 60 ca,s) 60 (9,1)
29,4 (8,0) 45 (3,8) too (9,1)
235(I), 209(II)
E, E
(IIa}
(Ic)
{Id
Z, Z
E, Z
(Ib) Z, •
E, E
Intensity, % (E, eV) {Ia}
Ions, m / e
(8,9) 20,3 (5,6) 70 (8,6) io (8,6)
(6,3) 48
27
(8,3) t0,3 (6,9) 4,5 (9,0) 24 (9,0) t9 (4,7) 80 (8,9) 6 (8,4) t6,5 (5,6) 45 (9,4) 4 (8,6)
41 (6,3) 6t (8,9) 23 (5,6) 6t (8,6) 9 (8,6)
(8,9) 4 (8A) 18,5 (5,6) 27 (9,4) 2 (8,6)
(4,7) 70
(8,6) t5 (8,6)
(5,6) 10o
45 (6,3) 55 (8,9) 18
I (8,6)
(9,4)
20,5
(5,6)
(8,9) 7 (8A) 10
63
(4,7)
t7,5
(9,0) 26 (9,0)
5,5 (6,8) 22 (8,8) t3 (6,8) 50 (9,5) 20,5 (6,8) t9,5 (8,3) 19,5 (6,9) 5
22,7 (6,8) 4t (3,8) 27 (6,8) t00 (9,5) 32 (0,8) 32 (8,3) 13,5 (6,9) 2 (9,0) i3,5 (9,0) 32 7,3 (6,8) 19,7 (3,8) t8 (6,8) 1o0 (9,5) 29,5 (6,8)
Z, Z
{iid)
{nc} E, Z
3,7, l l-
(IIb) Z, E
TABLE i. Negative-lon Mass Spectra Derived by Dissociative Electron Capture of Ethyl Esters of Isomeric Trimethyl-2,6,1 0-dedecatriene(la-d) and 1 0-Oxo-3, 7-dimethyl-2,6-decadienecarboxylic Acids (IIa-d
I
d "i m/e s91
~\
,
Fig. i . O e p e n d e n o e o f t h e e f f e o t i v e yield of ions with m / e 217 and 191
N v 5
I 7
5
I 8
I g
I flE,eV
fO
ions. R is highly p r o b a b l e that the NI's with m / e 95 and 41 in the e a s e of (Ia-d) and those with m / e 163, 135, 95, and 41 in the c a s e of (IIa-d) have the s a m e s t r u c t u r e s . Then we m a y r e a s o n a b l y s u p p o s e that t h e i r p a r e n t ions a r e the NI's with m / e 217 f o r (Ia-d) and m / e 191 f o r (IIa-d); s u b s e q u e n t f r a g m e n t a t i o n t a k e s place at the s i n g l e bonds and is a c c o m p a n i e d by H a t o m m i g r a t i o n to the ion f o r m e d f r o m the r a d i c a l f r a g m e n t . The ions with m / e 81 a l s o have an analogous s t r u c t u r e , but they p r o b a b l y o r i g i n a t e in the p r o c e s s m / e 127 ~ r o l e 81 + 46, s i n c e t h e y a r e a l s o a p p a r e n t at e l e c t r o n e n e r g i e s of ~ 5 eV. M a i n l y ions with m / e 127 in this e n e r g y r e g i o n a r e f o r m e d with m a x i m u m yield at 4.8 eV. The shift of the r e s o n a n c e p e a k of the ions with m / e 81 t o w a r d high e n e r g y and the s i m i l a r i t y b e t w e e n the p r o c e s s of f o r m a t i o n of this ion and that of the ions with r o l e 217 and 191 i n d i r e c t l y s u p p o r t this s u p p o s i t i o n . Thus, the m o l e c u l a r NI's of the f a r n e s y l e s t e r s and oxo e s t e r s have s i m i l a r f r a g m e n t a t i o n p a t h w a y s . D i f f e r e n c e s a r e a p p a r e n t only in the f o r m a t i o n of the e x t r a ions with m / e 163 and 135 f r o m the oxo e s t e r s (IIa-d), p r o b a b l y b e c a u s e the f r a g m e n t a t i o n of the m / e 191 ion with c l e a v a g e of CO and O - - - - C H - C H = C H 2 r e s p e c t i v e l y is e n e r g e t i c a l l y a d v a n t a g e o u s . Table 1 shows that the oxo e s t e r s (IIa-d) t y p i c a l l y have an a d d i t i o n a l r e s o n a n t s t a t e at l o w e r e n e r g y (6.8 eV), which is a l s o a p p a r e n t on the plots of the e f f e c t i v e yield f o r the NI's with m / e 217 and 191 {Fig. 1). This r e s o n a n c e is o b v i o u s l y due to e l e c t r o n c a p t u r e in the o r b i t a l s of the f o r m y l g r o u p , although the r e s o n a n t s t a t e of a l d e h y d e is n o r m a l l y found at h i g h e r e n e r g y ( ~ 8 eV) [8]. The r e d u c t i o n in e n e r g y in this c a s e b e c o m e s und e r s t a n d a b l e if we a s s u m e the i n t e r a c t i o n b e t w e e n the CHO and CO2Et g r o u p s l o c a t e d on o p p o s i t e ends of the oxo e s t e r s (IIa-d) due to t h e i r s t e r i c p r o x i m i t y in the folded c o n f o r m a t i o n . In this c a s e the fact that the f r a g m e n t a t i o n pathways of the oxo e s t e r s (IIa-d) r e m a i n a l m o s t the s a m e as in the c a s e of the f a r n e s y l e s t e r s (Ia-d) can be i n t e r r u p t e d in the following way. The e l e c t r o n is i n i t i a l l y c a p t u r e d in the o r b i t a l s of the i n t e r a c t i n g CHO and CO2Et g r o u p s of (IIa-d). A f t e r this the bond b e t w e e n the groups b r e a k s and the e l e c t r o n is t r a n s f e r r e d to the e s t e r group, which a l s o c o n t r o l s the s u b s e q u e n t f r a g m e n t a t i o n , as in the c a s e of the e s t e r s (Ia-d). In connection with o u r r e s u l t s we note that folded c o n f o r m a t i o n s of p o l y u n s a t u r a t e d compounds have r e c e n t l y been d e t e c t e d in s o l u t i o n by independent methods as e x e m p l i f i e d by p e r o x y a r a c h i d o n i c acid [9] and a r o m a t i c e s t e r s of f a r n e s o l and g e r a n y l g e r a n i o l [10]. On the b a s i s of o u r r e s u l t s we can w r i t e the f o r m a t i o n of the NI's of (Ia-d) and (IIa-d) as
2-s
I
o-
~
I
E,
~
I
o~t
c
i ~ ,
__~
~-
oi-
(Iaj
i"
_
I
,o_ o
o ,~/. 209
256
oE (LT.a)
o
~ ~ i . 2a7
\o~ / . !~
%%o,~I.-~
CONCLUSIONS
The ester group has a decisive role in the fragmentation process of the molecular negative ion following dissociative electron capture by the ethyl esters of isomeric 3,7, ll-trimethyl-2,6,10-dodecatrieneand 10oxo-3,7-dimethyl-2,6-decadienecarboxylic acids. LITERATURE i. 2. 3. 4. 5. 6. 7. 8. 9. i0.
CITED
V.I. I(hvostenko, V. A. Mazunov, I. I. Furlei, V. P. Yur'ev, and G. A. Tolstikov, Zh. Obshch. Khim., 44, 146 (1974). G.A. Tolstikov, V. S. Fal'ko, L. A. Baltina, and V. I. Khvostenko, Izv. Akad. Nauk SSSR~, Ser. Khim., ]_051 (1977). L.A. Baltina, V. S. Fal'ko, V. I. Khvostenko, and G. A. Tolstikov, Zh. Obshch. Khim., 417, 2379 (1977). L.A. Baltina, I. I. Furlei, P. F. Vlad, V. I. Khvostenko, G. A. Tolstikov, and V. S. Fal'ko, Khim. Prirodn. Soedin., 454 (1978). V.N. Odinokov, V. R. Akhunova, G. A. Tolstikov, A. V. Semenovskii, and V. I. Mizyuk, Zh. Org. Khim., 14, 1851 (1978). N. Ya. Grigor'eva, I. M. Avrutov, A. V. Semenovskii, V. N. Odinokov, V. R. Akhunova, and G. A. Tolstikov, Izv. Akad. Nauk SSSR, Ser. Khim., 382 (1979). A. Sh. Sultanov, U. M. Dzhemilev, V. I. Khvostenko, G. A. Tolstikov, R. I. Khusnutdinov, and S. R. Rafikov, Dokl. Akad. Nauk SSSR, 238 ,, 367 (1978). I. Kh. Aminev and V. I. Khvostenko, VINITI Dep. No. 3643-71 (Feb. I, 1971). E.J. Corey, H. Niwa, and J. R. Falck, J. Am. Chem. Soc., I01, 1586 (1979). R. Breslow and L. M. Moresca, Tetrahedron Lett., 887 (1978).
257