The steroid cyclophanes with a cyclic core consisting of a 1,6,20,25-tetraaza[6.1.6.1]paracyclophane connected to four steroid moieties (cholic acid or cholanic acid) through a flexible l-lysine spacer were spread on water as Langmuir monolayers. The pi-A isotherm of the cholic-type steroid cyclophane includes a transition to the condensed phase with a limiting area of approximately 2 nm(2). This value is close to the cross-sectional area of the steroid cyclophane with a standing-up conformation of the cholic acid moieties, strongly suggesting that the cavity converts from a two-dimensional cavity to a three-dimensional cavity upon compressing the monolayer. Surface-reflective fluorescence spectroscopy of the monolayer using an aqueous fluorescent probe (6-(p-toluidino)naphthalene-2-sulfonate (TNS)) showed an abrupt increase in the TNS fluorescence intensity at a molecular area of 2 nm(2). Efficient binding of the guest probe would occur upon the completion of the three-dimensional cavity. Repeated compression and expansion induces periodic changes in the fluorescence intensity. This indicates a piezoluminescence effect through the catch and release of the TNS guest upon dynamic cavity formation. Analyses of the binding behavior of TNS to the steroid cyclophane resulted in binding constants in the range of approximately (5-9) x 10(4) M(-1) which are similar to that observed in lipid bilayer media (K = 5.1 x 10(4) M(-1)). The fluorescence intensity within the condensed phase was significantly increased with increasing pressure, suggesting that suppression of the molecular motion of the bound TNS may retard the nonemission process. Similar monolayer experiments were carried out with the monolayer of the cholanic-type steroid cyclophane that cannot form an open conformation on water. Both the phase transition in the pi-A isotherm and the change in the fluorescence intensity were negligible, confirming that the dynamic characteristic of the cavity is indispensable for the efficient pressure-induced binding of the guest and the consequent luminescence.

InI-mediated direct allylation of carbonyl compounds with allylic alcohols proceeded smoothly with catalytic amounts of Ni(acac)(2) and PPh(3) to give the corresponding homoallylic alcohols in high yields. Allylindium compounds were shown to be the real allylating agents in the present system. Substituted allylic alcohols gave branched homoallylic alcohols with syn-selectivity irrespective of the geometry of the starting allylic alcohols, whereas high anti-selectivity was observed when a bulky substituent is present in the allylic alcohols. The outcome of the diastereoselectivity is discussed on the basis of the reaction mechanism, comparing with the corresponding Pd-catalyzed version. Another distinct behavior between the Ni- and Pd-catalyzed allylation was demonstrated in the reaction of hex-1,5-diene-3,4-diol derivatives: the Pd catalyst did not give any coupling product, whereas the Ni-catalyzed InI-mediated reaction with benzaldehyde afforded the 1:1 and 1:2 adduct diols selectively depending on the reaction conditions.

In the presence of InI, Ni(acac)2 and PPh3, several 1,3-dienes were reacted with two molecules of aldehyde to give the corresponding 1,4- and 1,6-diols. The regioselectivity of the 1,4-/1,6-diol was efficiently regulated by the addition of water; the 1,6-diol was obtained selectively in dry THF, whereas the 1,4-diol was obtained predominantly in DMI containing a small amount of water.

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