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Effect of arene–arene interaction in stereoselective MCPBA epoxidation was investigated using 5,6-dimethyl-2-phenyl-3a,4,7,7a-tetrahydroisoindole-1,3-diones 1. From the good correlation between the stereoselectivity of the products and Hammett’s coefficients of para-substituents (σP) on the phenyl group, it was found that polar/π interaction between the phenyl group and MCPBA is the main interaction for controlling the stereoselectivity in the reaction. Other arene–arene interactions, charge-transfer complexation and edge-to-face interaction, were assumed to be much weaker than polar/π interaction in this reaction.

Control of three modes of intramolecular reactions, [2+2] and [4+2] cycloadditions, and Type-II cyclisation, is attempted in the photochemical reaction of N-(naphthylethyl)prop-2-enamides. The reactions are affected by the enamide substituents and the sensitisation conditions used. Acryloyl derivatives undergo [2+2] cycloaddition and Type-II cyclisation. The two reactions occur selectively depending on the sensitiser used, benzophenone sensitisation affording the [2+2] cycloadducts whereas the Type-II cyclisation products are obtained exclusively by benzene sensitisation. In contrast, photolysis of cinnamoyl derivatives results in the formation of [4+2] cycloadducts.

Intramolecular diastereoselective [4 + 4] photocycloadditions of acyclic imides 1a and 1b possessing anthracene and naphthalene moieties were carried out in the solid state and in solution. For 1a, novel reversal of diastereoselectivity was observed on changing the reaction phase. The diastereomeric excess was changed from −60% de in the solid state at 60 °C to 70% de in acetone at −78 °C. Almost 100% de was observed for the solid-state photocycloaddition of 1b. The reactivity of 1a in the solid state was discussed based on its single crystal X-ray analysis.

Guest inclusion abilities of two rotamers, anti- and syn-N,N′-bis-(2-tert-butylphenyl)naphthalene-1,4,5,8-tetracarboxylic diimides 1 and 2, were investigated. Rotamers 1 and 2 were synthesised from 2-tert-butylaniline and naphthalene-1,4,5,8-tetracarboxylic dianhydride and separated by conventional column chromatography on silica gel. Recrystallisation of 1 from chloroform in the presence of a guest molecule (3 mole equivalents) was performed, and 15 guest molecules were included with a variety of host∶guest ratios, 1∶1 (chloroform, pyridine, 4-picoline, benzene, quinoline, diphenylacetylene, naphthalene, and p-toluidine), 1∶2 (phenol, 3-ethylphenol, 4-methoxyphenol, indole, 5-methylindole, and tetrathiafulvalene), and 1∶4 (benzothiazole). In contrast, 2 showed no inclusion of guest molecules under the same conditions as those applied to 1. In order to investigate the intermolecular interaction in the crystalline state of 1, 2 and 1·(indole)2, X-ray diffraction of single crystals was measured and these structures were compared.

A clathrate host, N-[2-(3,5-dinitrobenzoylamino)-6-methylphenyl]phthalimide 1 is designed to achieve inclusion of N-substituted formamides. N,N-Dialkylformamides HCONR2 of various sizes 2a–e [2a: R = Me; 2b: R = Et; 2c: R = Pri; 2d: R2 = –(CH2)5–, 2e: R2 = –(CH2)2O(CH2)2–] and dimethyl sulfoxide have been included as the guests in a clathrate host 1, in the ratio 1∶1 in each case. The interaction between the host and guest has been investigated by X-ray analysis of complex 1·2c (1∶1). The phthalimide plane and the N-phenyl group are orthogonal, which makes a suitable space for recognition of the formamides.

N-Benzoyl-N-benzylcinnamamides 1, N-acetyl-N-(1-benzyl)cinnamamides 3 and N-[(1-benzyl)aminocarbonyl]-N-(1-benzyl)cinnamamides 5 have been irradiated by a high-pressure mercury lamp in the presence of benzil in benzene at room temperature to give 3-azatricyclo[5.2.2.01,5]undeca-8,10-dien-4-ones 2, 4 and 6 with high stereoselectivity. These are the first photo[4+2]cycloadducts of an enone and a benzene ring.

The photocyclisation of N-cinnamoyl-1-naphthamides 1a–f was examined in the solid state and in solution. Three types of cyclisation, intramolecular 2π+ 2π and 4π+ 2π, and intermolecular 2π+ 2π cyclisations were observed in the solid state. The ratios of these products were largely dependent on the substituents at the para-position of the cinnamoyl moiety. Single-crystal X-ray crystallographic analysis of 1b showed that the intermolecular distance between the two double bonds was 4.34 A. Amides with bulky substituents preferred intramolecular 2π+ 2π cyclisation. In contrast to the solid-state photochemistry, only intramolecular cyclisation was observed in solution. The ratios of 2π+ 2π and 4π+ 2π cyclisation products were irradiation time dependent. It was found that the 2π+ 2π cycloreversion and rearrangement from the 2π+ 2π product to the endo 4π+ 2π isomer were the cause of this dependency.

A novel three-component coupling reaction of methyl hydrogen maleate 1, a carbodiimide 2, and an alcohol or amine gave derivatives of N-carbamoylaspartic acid (3) in moderate to excellent yields. In the coupling, an intramolecular Michael addition of the acylisourea 6 subsequently occurs to give a new intermediate, 2-iminooxazolidin-5-one 7. The addition of alcohol or amine to the second intermediate 7 completes the three-component coupling.

A novel and highly stereoselective 5-endo cyclisation of epoxy-allylic stannanes 1 promoted by BF3–Et2O has been discovered. The same reaction occurs with lower regio- and stereo-selectivity via an allylic lithium as a result of transmetallation. The selective formation of trans-3-alkenylcyclopentanols is expected to be of importance in terpenoid syntheses.

Lewis acid and butyllithium promoted cyclisations of epoxy-allylic stannanes have been studied. The regio-and stereo-chemistry of the cyclisations are described. The stereoelectronically favoured 5and 6-membered ring formations have been explained by either the electronic nature of, or the steric hindrance induced by, the epoxide moiety of the substrates depending on whether the reaction was promoted by a Lewis acid or butyllithium, respectively. The different stereoselectivities observed are brought about by the mode of reaction. The contrasting results for the 5-membered ring formations are particularly remarkable.

The intramolecular radical cyclisation of cyclic homoallylic xanthates were explored. In five- or six-membered ring systems, the homoallylic xanthates were easily cyclised to give fused thionolactone derivatives. The thionolactones were converted into their corresponding lactones in high yield, which constitutes a transformation of homoallylic alcohols into lactones.

Lewis acid-induced cyclisation of epoxy-allylic stannanes to give carbocyclic alcohols has been studied. The regio- and stereo-selectivities shown in the reaction are discussed in terms of the effects of substituents on the epoxide rings and of the Lewis acids employed.