5250
J . Am. Chem. SOC.1987, 109, 5250-5260
Nitrogen Extrusion from the Bis-Azoalkane [anti(syn)]-7,7’-Bi-2,3-diazabicyclo[2.2.1 ]hept-2-ene1 Waldemar Adam,*+Klaus Hannemann,+*Eva-Maria Peters,$Karl Peters,$ Hans Georg vnn Schnering,t and R. Marshall Wilson*s Contributionfrom the Institut fur Organische Chemie der Universitat Wiirzburg, A m Hubland, 0 - 8 7 0 0 Wiirzburg, Federal Republic of Germany, the Max-Planck- Institut fur Festkorperforschung, 0-7000 Stuttgart 80, Federal Republic of Germany, and the Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221. Received September 29, 1986 Abstract: The bis-azoalkane 5 has been synthesized and its loss of nitrogen studied under photochemical and thermal conditions. Even with intense argon laser irradiation, the photolysis of 5 proceeds through a stepwise loss of nitrogen to form the four isomeric azoalkanes lla-d. Prolonged irradiation leads to the further loss of nitrogen and the formation of the three isomeric bibicyclo[2.1.O]pentanes 12a-c. Under the laser conditions applied in this work, no evidence was obtained for the formation of the tetrayl 4 through the simultaneous or near simultaneous loss of both nitrogen units. Thermolysis of 5 afforded similar results. At 450 ‘ C , 1,l’-bicyclopentene(13) was the major product. This substance was shown to arise from the isomerization of the bibicyclo[2.l.O]pentanes 12. The ratios of products derived from 5 and the isomers of 11 through the loss of nitrogen are dependent upon the reaction conditions, direct or sensitized photolysis and thermolysis. These product ratio studies provide some interesting insights into the possible mechanisms of these nitrogen extrusion reactions. Recently, Dougherty and co-workers have discussed the formation of the tetrayl 1 derived from a double extrusion of nitrogen from the bis-azoalkane l 3 Other bis-azoalkanes are known from which tetrayl formation might be feasible? However, in the case of 3, for example, no tetrayl formation has been observed.5 In this account we wish to report our initial efforts to observe the formation of the tetrayl 4 through the nitrogen extrusion from the bis-azoalkane 5. This system is particularly appealing since the tetrayl 4 might be expected to collapse to the known hydrocarbon 6.6 Consequently, the observation of 6 among the nitrogen extrusion products of 5 might be taken as evidence for the formation of tetrayl 4. The additional intriguing possibility exists that a single nitrogen extrusion from the anti-diazabicycloheptene moiety of 5 would give rise to the diyl 7, which in turn might undergo intramolecular trapping’ with the remaining azo linkage to form the hydrazine 8.
n
Scheme I
x I) KOH
2) CUCI,
.
-
anti-syn stereochemistry (see Figure 1 and the Experimental Section for the crystallographic parameters) .9
Y H+
5
8
Synthesis of the Bis-Azoalkane5. The bis-azoalkane 5 is readily available from the known biurazole 9, which is formed in the double Diels-Alder addition of N-phenyltriazolinedione (PTAD) to 9,lO-dihydrofulvalene (Scheme I).8 Catalytic hydrogenation of 9 to the saturated biurazole 10 followed by hydrolysis and oxidation affords the bis-azoalkane 5 in high yield. The stereochemistry of the double PTAD adduct with 9,lOdihydrofulvalene was not established previously.8 In this work a single-crystalX-ray structure determination for the bis-azoalkane 5 derived from Paquette’s PTAD adduct 9 demonstrates that the series of compounds shown in Scheme I has the unsymmetrical
’Institut fur Organische Chemie der Universitat Wiirzburg. * Max-Planck-Institut fur Festkorperforschung. University of Cincinnati.
b
-
4
3
2
I %
(1) For a preliminary communication of this work, see: Adam, W.; Hannemann, K.; Peters, E.-M.; Peters, K.; Schnering, H. G.; Wilson, R. M. Angew. Chem. 1985,97,417(Angew. Chem., Int. Ed. Engl. 1985,24,421). (2) This work constitutes part of the Ph.D. Thesis of K. Hannemann, Wiirzburg, 1984. (3) . . (a) . . McElwee-White. L.: Goddard, W. A,, 111: Douahertv, D. A. J . Am. Chem. SOC.1984,106, 3461. (b) McElwee-White, L.: Dougherty, D. A. Ibid. 1984, 106, 3466. (4) Adam, W.; DeLucchi, 0. Angew. Chem., Int. Ed. Engl. 1980,19,762. ( 5 ) Bushby, R. J.; Mann, S.; Jesudason, M. V. Tetrahedron Lett. 1983, 24,4743. (6) Paquette, L. A.; Davis, R. F.; James, D. R. Tetrahedron Lett. 1974, 1615. We thank Professor Paquette for providing us with an ’H NMR spectrum of the hydrocarbon 6. (7) For other examples of intramolecular diyl trapping reactions, see: Little, R. D.; Muller, G. W. J . Am. Chem. SOC.1979,101, 7129. Little, R. D.; Stone, K.J. Ibid. 1983, 105, 6976. (8) Paquette, L. A,; Wyvratt, M. J.; Berk, H. C.; Moerck, R. E. J . A m . Chem. SOC.1978, 100, 5845. (9) The stereochemical descriptors, anti-syn and endo-exo, used in this paper for compounds 5, lla-d, and 12a-c are applied in accord with section 203(B) and - ( C ) of Appendix IV to the 1985 Chemical Abstracts Index Guide. Thus, for 5 and lla-d the anti and syn descriptors reference the configuration of the one-carbon bridge of the 2,3-diazabicyclo[2.2.l]hept-2-ene moieties to the azo bridge. For lla-dand lh-,,the endo and exo descriptors reference the configuration of the one-carbon bridge of the bicyclo[2.1 .O]pentane moieties to the two-carbon bridge. We thank K. L. Loening for his suggestions regarding the nomenclature of these molecules.
0002-7863/87/1509-5250$01 .50/0 0 1987 American Chemical Society
J . Am. Chem. SOC.,Vol. 109, No. 17, 1987
Nitrogen Extrusion from a Bis-Aroalkane
5251
Scheme I1
Anti, Exo
4
Exo, Exo
6
.
Syn, Endo
2
l
