2776 J . Org. Chem., Vol. 43, No. 14, 1978
Taskinen
Table 11. IH NMR C h e m i c a l S h i f t Data (6 V a l u e s in p p m from Internal MedSi) for 2 - S u b s t i t u t e d 4-Methylene-1.,3dioxolanes (3a-m) Compd
HA
3a b
3.88 4.33 3.84 4.27 3.75 4.20
C
d e
CHz
HB
h i j k
3.74 3.90 3.77 3.67 3.74 3.88 3.85 4.00
4.20 4.30 4.23 4.12 4.23 4.35 4.30 4.40
1 m
3.80 3.88
4.28 4.32
f g
Other protons
4.33 5.18 4.27 5.22 ( C H ) , 1.38 (Me) 4.35 4.87 (CH), ca. 1.8 (CH of t h e i-Pi, group), 0.95 (2 Me) 4.36 4.78 (CH), 0.92 (3 Me) 4.30 5.95 (CH), 7.25 (aromatic protons) 4.48 1.42 4.37 1.27 (Me), 0.94 (2 Me) 4.50 1.30 (Me), 0.97 ( 3 Me) 4.46 5.88 (CH, 3.28 (MeO) 4.41 5.84 (CH), 3.54 (CH2), 1.20 (Me) 4.49 6.13 (CH), 6.32, 4.63, and4.20 (olefinic protons) 4.51 3.22 (MeO), 1.52 (Me) 4.44 3.27 (MeO)
aReference 16.
2-methyl-4-methylene-1,3-dioxolane (3b) 97 "C (760 Torr), 2isopropyl-4-methylene-1,3-dioxolane(3c) 40 "C (20 Torr), 2tert-butyl-4-methylene-1,3-dioxolane(3d) 130 "C (760 Torr), 2-phenyl-4-methylene-l,3-dioxolane (3e) 105 "C (10 Torr) 2,2dimethyl-4-methylene-1,3-dioxolane(3f) 106 "C (779 Torr), 2methyl-2-isopropyl-4-methylene-1,3-dioxolane (3g) 48 "C (20 Torr), and 2-methyl-2-tert-butyl-4-methylene-1,3-dioxolane (3h) 86-88 "C (90 Torr). 2-Methoxy-4-methylene-l,3-dioxolane (3i). Equimolar amounts of HC(0Me)S and 3-chloro-1,2-propanediol were heated in a distillation apparatus in the presence of some p-toluenesulfonic acid until the evolution of MeOH ceased. The product was treated with KOH to give 3i, b p 54 "C (60 Torr). 2-Ethoxy-, 2-Vinyloxy-, 2-Methyl-2-methoxy-, and 2,2!-Dimethoxy-4-methylene-1,3-dioxolane(3j, 3k, 31, a n d 3m, Respectively). See preparation of 3i. Besides the diol, HC(OEt),, HC(OCH&H*C1)3, MeC(OMe)s,and C(OMeI4were used as the reagents (in the case of 3k, the initial reaction product was 242-chloroethyl)-4-chloromethyl-l,3-dioxolane, which required 2 molar iequiv of KOH for dehydrochlorination to the final product). Bp's: 3j 133 "C (97 Torr), 3k 36--39 "C (9 Torr), 31 ca. 65 "C (85 Torr), and 3m 152"C
(6 Torr).
4,4'-Dimethylene-2,2'-spirobi-1,3-dioxolane(4), bp ca. 95 "C (23 Torr), was prepared from C(OMe)4 and 2 molar equiv of 3chloro-l,2-propanediol,followed by dehydrochlorination. 'H N M R Spectra. The spectra were recorded a t 60 MHz in CC14 (no%, v/v) with MedSi as internal standard. The chemical shifts are given in 6 values (ppm) and the coupling constants in hertz. The spectra of 3a-m are given in Table 11. le:6.07 (Ha,J = 6.9), 4.46 (Hp), 1.55 (MeC=C),6.34 (H'J, 4.37 ( H 6 , J = 13.7),5.09 (H'@,J = 6.9), 1.41 (MeCH, J = 5.3), 5.94 (CH). 2e: 6.06 (Hm, J = 6.8), 4.45 (Hp), 1.56 (MeC=C, J,i, = 6.9, Jallylic= 1.7),5.06 (CH),5.02 and 5.20 (olefinic protons), 1.73 (MeC=C). 4: 3.97 and 4.43 (olefinic protons), 4.65 (CHz). I3C N M R Spectra. The spectra were recorded in CDC13 (200~6,v/v) with Me4Si as internal standard. For other details, see ref 13.
Acknowledgment. The author is grateful t o Mrs. H i l k k a Ollikka, B.S., and M r . Tapio L a n k i n e n , M.S., for s o m e synt h e t i c aid. Registry No.-Allyl 2-chloroethyl formal, 66291-03-0; acetaldehyde allyl vinyl acetal, 51914-88-6; methylacrolein diallyl acetal, 5187-69-9; methyl isopropyl ketone diallyl acetal, 66290-98-0; trimethoxymethane, 149-73-5; 3-chloro-1,2-propranediol, 96-24-2; tetramethoxymethane, 1850-142.
References and Notes Dolliver. T. L. Gresham, G. B. Kistiakowsky, E. A. Smith, and W. E. Vaughan, J. Am. Chem. SOC.,60,440 (1930). (2) J. B. Stothers, "Carbon-I3 NMR Spectroscopy", Academic Press, New York, N.Y., 1972, p 184. (3) H. Suhr, "Anwendungen der Kernmagnetischen Resonanz in der Organischen Chemie", Springer-Verlag. Berlin, 1965, p 143. (4) W. F. Reynolds and R. A. McClelland, Can. J. Chem., 55, 536 (1977). (5) R . T. C. Brownlee, G. Butt, M. P. Chan, and R . D. Topsom, J. Chem. SOC. Perkin Trans. 2, 1486 (1976). (6) M. A. Davis, J. Org. Chem., 32, 1161 (1967). (7) B. A. Trofimov, N. I. Shergina, E. I. Kositsyna. A. S. Atavin, A. G. Gusarov, G. M. Gavrilova, and I. S. Yemelyanov, Org. React. (USSR), 6, 902
(1) M. A.
(1969). (8) (9) (10) (11)
E. Taskinen, Tetrahedron, 34, 429 (1978). R.-M. Lequan and M.-P. Simonnin, Bull. SOC. Chim. Fr., 4419 (1970). E. Taskinen and P. Liukas, Acta Chem. Scand., Ser. 8, 28, 114 (1974). E. Taskinen, E. Kukkamaki, and H. Kotilainen. Tetrahedron, 34, 1203
( 1978). (12) E. Taskinen. Tetrahedron, 33, 353 (1977). (13) E. Taskinen, Tetrahedron, 34, 425 (1978). (14) E. Taskinen and H. Lahteenmaki, Tetrahedron 32, 2331 (1976). (15) E. Taskinen and H. Lahteenmaki, Finn. Chem. Lett., 47 (1978). (16) E. Taskinen, J. Chem. Thermodyn., 6, 1021 (1974). (17) H. 0. House and V. Kramar, J. Org. Chem., 28, 3362 (1963).
Carbon-13 Nuclear Magnetic Resonance Spectra of Divinyl Ethers Esko T a s k i n e n Department of Chemistry and Biochemistry, L'niuersity of T u r k u , SF-20500 T u r k u 50, Finland Receivzd Nocember 22, 1977 l.iC NMR chemical shifts have been determined for a number of alkyl- and aryl-substituted divinyl ethers. On the basis of the shift data for the olefinic carbons it can be shown that alkyl substitution a t one of the terminal ( p ) carbons of the divinyl ether skeleton leads to an enhanced conjugation between the 0 atom and the unsubstituted vinyl group, whereas there is a decrease in conjugation with the substituted vinyl group. This is likely to arise from the polar effect of the substituent, which opposes the accumulation of excessive negative charge (resulting from conjugation) on the substituted C atom. Thus the 0 atom conjugates more effectively with the other vinyl group. The results suggest further that unsubstituted or /3- (/3,$'-) substituted divinyl ethers have an essentially planar s trans,s-trans structure, while a-substituted divinyl ethers have a slightly nonplanar s-cis,s-trans structure, and cd-substituted divinyl ethers are markedly nonplanar so that 7i-p--7i conjugation is considerably weaker in these compounds than in the unsubstituted divinyl ether molecule.
In a previous paper,' the s p a t i a l structure of the divinyl e t h e r skeleton in alkyl-substituted divinyl ethers (I) w a s discussed on the basis of t h e r m o d y n a m i c data of isomeric interconversion. I n t e r e s t i n g i n f o r m a t i o n w a s also o b t a i n e d f r o m lH NMR s h i f t d a t a , which revealed that alkyl s u b s t i t uents m a y h a v e significant effects on c h a r g e d i s t r i b u t i o n in
'Me
I
0022-32631781'1943-2776$01.00/0 0 1978 American C h e m i c a l Society
I1
J . Org. Chem., Vol. 43, .Vo. 14, 1978 2777
13C NMR Spectra of Divinyl Ethers the divinyloxy system: substitution at C-pl increases electron density around C-p, but decreases it around C-p’, whereas substitution at C-a’ has a reverse effect. If it is assumed that in the unsubstituted divinyl ether molecule (I, Rl-Rs = H) P-p-P conjugation between the lone pair electrons of the 0 atom and the 7i electrons of the C=C bonds is equally distributed between the two vinyl groups, the above findings suggest that alkyl substitution at C-@’decreases conjugation with the substituted vinyl group but increases conjugation with the unsubstitutecl vinyl group. These effects are reversed if substitution occurs at C-a’. The aim of the present work was to study these effects in more detail by 13C NMR spectroscopy, which allows a direct “look” at the (C) atoms constituting the divinyl ethLer skeleton rather than just at atoms linked to it. The compounds investigated, together with their l3C NMR chemical shift data, are given in Table I. For comparison, related data for some a-substituted methyl vinyl ethers (11) are also included in Table 11.
Results and Discussion The data given in Table I enable us to evaluate the effects of the substituents attached to C-a’or C-@’onthe 13C chemical shifts of C-CY and C - d . For example, the Me group of I11 Me(’H=CH
CH=CH
\0
/
