Received 27 August 2013
In the title compound, C27H23N3O2, the geminal benzyl groups branching out from the methine adjacent to the isoxazole group are both syn-oriented to the methyl group of the pyridazinone moiety, as reflected by C-C distances of 3.812 (2) and 4.369 (2) Å between the methyl carbon and the nearest ring carbon of each benzyl group. This kind of conformation is retained in CDCl3 solution, as evidenced by distinct phenyl-shielding effects on the 1H NMR signals of the methyl H atoms. The isoxazolo[3,4-d]pyridazin ring system is virtually planar (r.m.s. deviation from planarity = 0.031 Å), but the N-bonded phenyl group is inclined to the former by an ring-ring angle of 55.05 (3)°. In the crystal, the T-shaped molecules are arranged in an interlocked fashion, forming rod-like assemblies along [10-1]. The molecules are held together by unremarkable weak C-HN, C-HO and C-H interactions (C-O,N,C > 3.4 A), while significant --stacking interactions are absent.
For chemistry of isoxazolo[3,4-d]pyridazinone preparation, see: Renzi & Dal Piaz (1965). For deprotonation with sodium alkoxides, see: Dal Piaz et al. (1975); Chimichi et al. (1986). For the rearrangement of the isoxazolo[3,4-d]pyridazinone ring system to pyrazole, see: Dal Piaz et al. (1985). For isoxazole lateral metalation, see: Natale & Niou (1984); Natale et al. (1985); Niou & Natale (1986); Schlicksupp & Natale (1987). For recent applications of lateral metalation and electrophilic quenching of isoxazoles to targets of biological interest, see: Nakamura et al. (2010); Hulubei et al. (2012). For a review of the lateral metalation and electrophilic quenching of isoxazoles, see: Natale & Mirzaei (1993).
Data collection: SMART (Bruker, 2012); cell refinement: SAINT (Bruker, 2012); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: publCIF (Westrip, 2010).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: QK2060 ).
NRN, JM, CG and CK thank the National Institutes of Health for grants NINDS P20RR015583 Center for Structural and Functional Neuroscience (CSFN) and P20 RR017670 Center for Environmental Health Sciences (CEHS), We also thank NINDS P30 (NN and JM), and the University of Montana Grant Program (NN).
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