7105
Communications to the Editor Scheme
of maysine, Dr. James Frye of the CSU Regional N MR Center for N M R spectra, and Dr. Phillip Ryan for the mass spectral data. Furthermore, it is a pleasure to acknowledge the technical assistance of Dr. Arthur Campbell and Mr. Curtis Gillespie.
I RO OEE e --*
Me
M~~Q
/
SEt
/
OEE
/
0
SEI SEt
SE t
14, -
X z H,
R
=
H
16, X -
0
0 II (OEI)*
z C-P I1
17 -
References and Notes Kupchan, S. M.; Komoda, Y.; Branfman, A. R.;Sneden, A. T.; Court, W. A,; Thomas, G. J.; Hintz, H. P. J.; Smith, R. M.; Karim, A,; Howie, G. A,; Verma, A. K.; Nagao, Y.; Dailey, R. G.; Zimmerly, V. A,; Summer, W. C. J. Org. Chem. 1977, 42, 2349: Corey, E. J.; Weigel, L. 0.;Floyd, D.; Bock, M. G. J. Am. Chem. SOC.1978, 100. . ~2916. ~. , .
Meyers, A. I.; Roland, D. M.; Comins, D. L.; Henning, R.; Fleming, M. P.; Shimizu, K. J. Am. Chem. SOC.1979, 101, 4732. Using various alkyl and acyl substituents on 6 gave epoxide mixtures as high as lO:l,but unfortunately rich in the wrong isomer, 7b. Separation on a IO-g scale was carried out using a Waters 500 highpressure LC system with 10% acetone-hexane. Retention times at 250 mL/min were 12.7min for 8a and 15.9min for 8b, respectively. Meyers, A. I., Shaw, C. C.; Horne, D. A.; Trefonas, L. M.; Majeste, R. M. Tetrahedron Left. 1975, 1745. Meyers, A. I.; Slade, J.; Smith, R. K.; Mihelich, E. D.; Hershenson, F. M.; Liang, C. D. J. Org. Chem. 1979, 44, 2247.Alternatively, the mixture in 11 was separated on Waters 500 LC using 7 % acetone-hexane. Both isomers of 11 were obtained pure and examined at 100 MHz. The protons at C-7(6 4.05,4.06)were shown to be a quartet (J = 5.8Hz) in one isomer and a doublet of doublets of doublets (J, = 8.6,J2= 5.6.J3= 3.1 Hz) for the other. Projections fully support the erythro isomer having the smaller J value between methine protons. Physical data for 3: pale yellow viscous oil; NMR (CDC13) 6 0.07(s,6),0.91 (~,9),1.0-2.7(m),2.83(d,J=9Hz,1),3.2-4.3(m),4.7(m,1),8.9(two formyl signals due to diastereomers generated by the ethoxyethyl masking group). The ratio of diastereomers in 13 was found to be 1:l as determined by high-pressure liquid chromatography on 19 and (*)-I. K. Narasaka, A. Morikawa, K. Saigo, and T. Mukaiyama, Bull. Chem. SOC. Jpn., 50, 2773 (1977).
A. I. Meyen,* Daniel L. Comins, Dennis M. Roland
(concentration of 16,5 X M), -78 to 25 "C, 10 h) and afforded the macrocycle 17 as the pure E isomer in 56% yield after PLC (IR (film) 1663 cm-I). The thioacetal was cleanly removed (95%, 2.2 equiv of HgC12, 2.5 equiv of CaC03, 4:l C H ~ C N - H Z O to ) the ketone 18 (IR (film) 1718,1663 cm-l) and the ethoxyethyl (EE) group was quantitatively removed (0.5 N HCI-THF, 0 "C) to the hydroxy ketone 19 (IR (film) 3420, 1720, 1660 cm-I). The final synthetic step was carried out by in situ preparation (PhOCOCI, pyridine, EtzO) of the mixed carbonate 20 (IR (film) 1754 cm-l) and followed immediately with liquid ammonia a t -78 "C. After warming to ambient temperature, workup and preparative layer chromatography (silica gel) gave a product (Rf0.13, 20% benzene-ethyl acetate) which was identical, except for optical rotation, with an authentic sample of (-)- maysine:' I R (film) 1709, 1662, 1628, 1575, 1088 cm-I;NMR (CDC13) ofselected proton signals 6 1.OO (s, 3, C-4 CH3), 1.26 (d, J = 6.1 Hz, C-6 CH3), 1.64 (br s, C-14 CH3), 2.62 (d, J = 9.6, C-5 H), 3.27 (s, C-10 CH3O), 5.66 (d, J = 15.5 Hz, C-2 H), 6.38 (d, J = 15.5 Hz, C-3 H); mass spectrum (70 eV, 170 "C) m/e 546 (M+), 528 (M' - 18), 485 (M+- 61, - ( H 2 0 HNCO), base peak), 470 (M+ - 76), 450 (M+ - 96); UV (EtOH) X 226, 242, 252,280, 288 nm. High-pressure liquid chromatographic (Waters 244) comparison using a 4 mm X 30 cm p-Porasil column and eluting with 50% ethyl acetate-chloroform (0.5% ethanol) a t a flow rate of 5 mL/min gave identical peaks for synthetic and natural maysine a t a retention time of 5.2 min. Studies are continuing to reach additional members of this class of macrocycles and these will be described i n future reports.
+
Acknowledgment. The authors are grateful to the National Institutes of Health (CA-16051) for financial support for this program. An N I H postdoctoral Fellowship to D. M. Roland and a travel grant from the Deutsche Forschungsgemeinschaft to R. Henning are also gratefully acknowledged. We thank Dr. Albert T. Sneden for his kind assistance and authentic samples
Rainer Henning, Kimihiro Shimizu Department of Chemistry, Colorado State Unicersity Fort Collins, Colorado 80523 Receiced July 16, I979
A Weakly Chemiluminescent Dioxetanimine' Sir: Dioxetanones (a-peroxylactones) are an interesting class of high energy compounds because of their potential involvement in the light-forming step of many luminescent organisms2 Particularly noteworthy is the fact that the yield of light production from some simple alkyl-substituted dioxetanones is greatly increased in the presence of fluorescent aromatic hydrocarbons with low oxidation potentials. Schuster and Adam ascribed this interesting finding to the occurrence of a chemically initiated electron-exchange luminescence (CIEEL).3 Recently, the reaction of ketenes with singlet oxygen has been found to be an useful method for the synthesis of d i o x e t a n o n e ~As . ~ the continuation of our search for new chemiluminescent system^,^ we now report the synthesis of N-tert-butyldimethyldioxetanimine (2) through the photooxygenation of N-tert-butyldimethylketenimine (1) and show its chemiluminescence properties. Photooxygenation6 of 1 (0.1 M) for 1 h a t -78 "C in CFC13 using tetraphenylporphine as sensitizer led to complete disappearance of 1. Direct iH N M R analysis (100 MHz) of the reaction solution at low temperature (-70 "C) indicated a mixture of 2 (65%), acetone (3, 30%), rert-butyl isocyanate (4, 30%), and tert-butyl isocyanide ( 5 , 5%).' The dioxetanimine 2 showed two singlet resonances at 6 1.22 (9 H) and 1.64 (6 H). When the reaction solution was warmed to temperatures above -30 "C, the ' H N M R spectrum of 2 was completely converted into that of a mixture of 3 and 4 within a few minutes.'5
0 1979 American Chemical Society
7106
Journal of the American Chemical Society
/
101:23
/
November 7, 1979
Table I. Comparison of the Chemical Properties of N-tert-Butyldimethyldioxetanimine(2), Tetramethyl-I ,2-dioxetane (7), and
Dimethvldioxetanone (8) 39,
'9, %
%
E,, kcal/mol
650
18
no
*+ wh",
no
Wb
2
3.4 x 10-3
7
30"
0.15"
200
28 "
8
1.5c
0.1'
15
22c
5.2 X
reaction products with Ph3P
39/19
CIEEL
0
0
% :
1.1f a
Reference 16a. Reference 8. Reference 3a. References 3b-d. e Turro, N. J.; Ito, Y., unpublished results. f Reference 19. The value
is the sum of 39and '9.
The product 2, which was assigned a dioxetanimine structure, is not polymeric, since 2 could be distilled through a cooled (-30 to -20 "C) fractionating column a t bath temperatures below -20 "C and a t 0.1 mmHg, although the majority of it decomposed to 3 and 4 during the distillation. The dioxetanimine 2 exploded in a solid state. Addition of an equimolar amount of triphenylphosphine to the solution of 2 in CFC13 a t -78 OC, followed by maintenance of the mixture a t the same temperature for 1 h, gave a phosphorane 6 in 75% yield (IH N M R ) . This reaction is characteristic of 1,2-dioxetanes, e.g., 7.8 After removal of the solvent and the volatile byproducts (3-5) at reduced pressure from an ice bath, the N M R spectra of the residue which consisted of 6 and triphenylphosphine oxide (3:l) were measured in CC14. 6: IH N M R 6 0.93 (s, 9 H), 1.53 (s, 6 H), 6.9-7.3 (m, 15 H); 3'P N M R 34.0 ppm upfield from the external standard of 85% H3P04.*Thermolysis of the solution of 6 in CC14 a t 60-65 "C for 30 min and the subsequent IH N M R analysis showed that 6 was quantitatively decomposed to acetone (3), tert-butyl isocyanide ( 5 ) , and triphenylphosphine oxide. The thermal decomposition of 2 to 3 and 4 was accompanied by chemiluminescence with added 9,10-dibronioanthracene (DBA) as a fluore~cer.~ It was found that tert-butyl isocyanate (4) had no absorption ( E < I ) a t wavelength above 250 nm and the fluorescence and phosphorescence of acetone (3) in acetonitrilelo were not measurably quenched by 4 (0.1 M ) , indicating that the lowest singlet and triplet energy levels of 4 are higher than those of 3. Since the sum of the reaction enthalpy (AH)" and the activation energy (E,)I5 for the conversion 2 3 4 was estimated to be -90 kcal/mol, both singlet ( E s 85 = kcal/mol) and triplet ( E T = 78 kcal/mol) excited states
of acetone (3) are energetically accessible from the transition state. The yields of triplet and singlet formation (3@and I @ , respectively) from the thermolysis of 2 were determined by Stern-Volmer plots using DBA and 9,lO-diphenylanthracene (DPA) as energy acceptors.I6 A 1,2-dioxetane derived from 2,3-diphenyl-1,4-dioxenewas used as a standard of photon emission." The yields, 3@ and I @ , of 2 (3.4 X and 5.2 X lo-%, respectively) were much lower than those of the analogous 1,2-dioxetanes, 7 and 8 (Table I). The chemical titration by fumaronitrileI* of the excited states of 3 from the thermolysis of 2 also showed that both of 3@ and I @ were below detectability by this method (
