@article{4d2686b1bf6e4f19a2b29fa2adad9ec5,
title = "Photochemical isomerisation of dimethyl 1,2-dihydropyridazine-1,2-dicarboxylate",
author = "Altman, {L. J.} and Semmelhack, {M. F.} and Hornby, {R. B.} and Vederas, {J. C.}",
note = "Funding Information: 6H (C02CH3) singlet at 3-81 8, 2H multiplet at 4.80 8, and a 4H multiplet a t 4-23 83. The spectral properties of the minor photoisomer are consistent with structure P I ) $ : n.m.r. two 3H (C02CH3) singlets a t 3.77 and 3.95 8 and an ABMX pattern, vA = 6.388 vB = 6.148, vM = 6.868, vX = 9.058, JAB 3-7, Jm 2.2, JAx 0.4, JBM 3.2, J 0.5 c./sec.; A,,, (C,H,,) 275 mp ( E 5700); i.r. (CC1,) NH absorption a t 3380 cm.-l and CO,CH, absorptions a t 1735 and 1745 cm.-l. The formation of (VI) is envisaged as a further photoreaction of (VIII) to give (IX) followed by a rearrangement N.m.r. spectral analysis demonstrated that (VI) was present in the crude photolysis product. to (VI). 687 Attempts at detecting (VIII) have thus far proved unsuccessful. .1 hv L J We thank the donors of the Petroleum Research Fund and Eli Lilly and Company for partial support of this work. (Received, Afivil 16th, 1968; Corn. 468.) 1 H. Prinzbach and I. H. Hartenstein, Angew. Chem. Internat. Edn., 1963, 2, 477; E. E. van Tamelen and S. P. Pappas, J. Amer. Chem. Soc., 1963, 85, 3297; G. M. Sanders and E. Havinga, Rec. Trav. chim., 1964, 83, 665; K. Dimroth, Ber., 1937, 70, 1631; E. J. Corey and J. Streith, J . Amev. Chem. Soc., 1964, 86, 950. 2 J. Rigaudy and J. C. BreliBre, BUZZ. Soc. chim. France, 1968, 455, report that the sole photoisomer of diethyl 3,6-diphenyl- 1,2-dihydropyridazine- 1,2-dicarboxylate is the hexatriene. in their preparation of diethyl 1,2-dihydropyridazine-l,Z-dicarboxylate. K. Alder and H. Niklas, Annalen, 1954, 585, 81. 4 We were unable to repeat the observations of M. Rink, S. Mehta, and K. Grabowski, Arch. Pharm., 1959,292, 225,",
year = "1968",
doi = "10.1039/C19680000686",
language = "English (US)",
pages = "686--687",
journal = "Chemical Communications",
issn = "1359-7345",
publisher = "Royal Society of Chemistry",
number = "12",
}