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Results of crystal structure analyses of seven 1,ELdisubstituted naphthalenes -8-hydroxynaphthalene-1-carboxamide) with a nucleophilic centre (N(CH3)2, OCH3, OH) at one of the peri positions and an electrophilic centre (carbonyl C ) at the other are described. All seven molecules show a characteristic distortion pattern: the exocyclic bond to the electrophilic centre is splayed outward, and the one to the nucleophilic centre is splayed inward; the carbonyl C is displaced from the plane of its three bonded atoms towards the nucleophile. This distortion pattern differs from that found in other 1,s-disubstituted naphthalenes and is interpreted as an expression of incipient nucleophilic addition to a carbonyl group. The crystal structure of 2b contains an ordered arrangement of equal numbers of amino acid and zwitterionic molecules. I) 2, 3,

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[reaction: see text] The n = 0, 1, and 2 ketones shown above undergo Yang photocyclization in solution, but only the n = 1 analogues react this way in the solid state. Based on X-ray crystallography, these differences in reactivity are attributed to an unusually large distance for 1,4-hydroxybiradical cyclization in the solid state for the n = 0 and 2 ring systems, which leads to predominant reverse hydrogen transfer (rht). Enantiomeric excesses of up to 99% can be achieved in the case of the n = 1 system through the use of the solid-state ionic chiral auxiliary method of asymmetric synthesis.

4,6-Dimethoxy-3-methyldihydrotriazine-2-one (1) undergoes a single-crystal to single-crystal reversible phase transformation at 319 K. The low-temperature phase crystallizes in monoclinic space group P2(1)/n with two crystallographically independent molecules in the asymmetric unit. The high-temperature phase is obtained by heating a single crystal of the low-temperature phase. This phase is orthorhombic, space group Pnma, with the molecules occupying a crystallographic mirror plane. The enthalpy of the transformation is 1.34 kJ mol(-1). The small energy difference between the two phases and the minimal atomic movement facilitate the single-crystal to single-crystal reversible phase transformation with no destruction of the crystal lattice. On further heating, the high-temperature phase undergoes methyl rearrangement in the solid state. 2,4,6-Trimethoxy-1,3,5-triazine (3), on the other hand, undergoes an irreversible phase transformation from single-crystal to polycrystalline material at 340 K with an enthalpy of 3.9 kJ mol(-1); upon further heating it melts and methyl rearrangement takes place.

C with a solution of CF3COOH (3 mL), CH2C12 (3 mL), and anisole (500 mg) gave, after purification on silica gel (99:l CHC1,-MeOH), 297 mg of pure 19 as a colorless powder: 'H NMR (250 MHz, CDCI,) 6 7.17-7.42 (m, 12 H, ArH), 6.19-6.96 (m, 2 H, ArH), 5.03 (s, OCH,Ph), 4.89 (dd, J = 5.0, 8.5 Hz, NCHArH), 4.57 (AB quartet, OCH,Ph), 4.08 (dd, J = 2.3, 5.4 Hz, CHNH,), 3.95 (dd, J = 10.1, 8.5 Hz, CHHOBn), 3.76 (dd, J = 10.1, 5.0 Hz, CHHOBn), 3.45 (app t, J = 5.5 Hz, p C-4 H), 3.06 (dd, J = 2.3, 5.6 Hz, a C-4 H), 1.92 (br s, NH,); IR (CHCI,) 1761 cm-I; MS (CI) m/e 403 (MH), 375. Acknowledgment. The financial support of the National Science Foundation (CHE 82-03366 and Departmental Instrumentation grants) is gratefully acknowledged.Registry No. 2 (R' = CH,Ph), 3010-05-7; 2 (R' = Ph), 3009-97-0; 2 (R' = cyclohexyl), 1074-58-4; 2 (R' = 2,5-(MeO),C6H,),

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