TpRuPPh 3 (CH 3 CN) 2 PF 6 (3 mol %) was very active in catalytic benzannulation of 1-phenyl-2-ethynylbenzenes in dichloroethane (60 °C, 36 h) to afford phenanthrene in 95% yield. This method is applicable to the synthesis of various polycyclic aromatic hydrocarbons via two-and four-fold benzannulations, including various substituted coronene derivatives (53-86% yields) using this catalyst at a moderate loading (10 mol %).

The skeletal reorganization of 1,6- and 1,7-enynes leading to 1-vinylcycloalkenes using Rh(II) as a catalyst is reported. Two possible isomers of 1-vinylcycloalkenes, type I and type II, can be obtained, the ratio of which are highly dependent on the substitution pattern of the enynes used. Formation of type I compounds involves a single cleavage of a C-C double bond, the product of which is identical to that of enyne metathesis. In contrast, the formation of type II compounds involves the double cleavage of both the C-C double and triple bonds, which has an anomalous bond connection. The presence of both a phenyl group at the alkyne carbon and a methyl group at the internal alkene carbon facilitates the formation of type II compounds. The electronic and steric nature of the substituents on the aromatic ring also affects the ratio of type I and type II. The nature of a tether also has a significant effect on the course of the reaction. Experimental evidence for the intermediacy of a cyclopropyl rhodium carbenoid, a key intermediate in the skeletal reorganization of enynes, is also reported. In addition to the skeletal reorganization of enynes, Rh(II) complexes were found to have a high catalytic activity for some cycloisomerization reactions of alkyne derivatives, including the bicyclization of enynes to bicyclo[4.1.0]heptene derivatives and the cyclization of alkynylfurans to phenol derivatives.

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Summary To assess the achievement of uniformity of radiobiological effectiveness at different depths in the proton spread-out Bragg peak (SOBP), Chinese hamster ovary (CHO) cells were exposed to 65-MeV modulated proton beams at the Research Center for Nuclear Physics (RCNP) of Osaka University. We selected four different irradiation positions: 2 mm depth, corresponding to the entrance, and 10, 18 and 23 mm depths, corresponding to different positions in the SOBP. Cell survival curves were generated with the in vitro colony formation method and fitted to the linear-quadratic model. With 137CS gamma-rays as the reference irradiation, the relative biological effectiveness (RBE) values for a surviving fraction (SF) level of 0.1 are 1.05, 1.10, 1.12 and 1.19 for depths of 2, 10, 18 and 23 mm respectively. A significant difference was found between the survival curves at 10 and 23 mm (P < 0.05), but not between 18 and 10 mm or between 18 and 23 mm. There was a significant dependence of RBE on depths in modulated proton beams at the 0.1 surviving fraction level (P< 0.05). Moreover, the rise of RBEs significantly depended on increasing SF level or decreased approximately in correspondence with irradiation dose (P = 0.0001). To maintain uniformity of radiobiological effectiveness for the target volume, careful attention should be paid to the influence of depth of beam and irradiation dose.Keywords: proton; spread-out Bragg peak; relative biological effectiveness; Chinese hamster ovary cellThe depth-dose curve for the single-energy proton beam has limited applications in clinical radiation therapy owing to the excessively narrow high-dose region. This region, also known as the Bragg peak, can be modulated by appropriate selection of a distribution of proton energies to produce a spread-out Bragg peak (SOBP) or a uniform region of full dose at the depth of interest. Dose uniformity across a target volume can be achieved with multiple X-ray beams. However, each X-ray beam features a greater dose in the entrance region than a corresponding proton beam, has a dose gradient across the target volume and delivers an undesirable dose to normal tissues distal to the target. Proton beams have none of these undesirable characteristics (Suit and Urie, 1992; Munzenrider and Crowell, 1994;Raju, 1996).Although SOBP produces an excellent physical dose distribution, there is a variation of linear energy transfer (LET) values at different depths in the SOBP, known as the LET gradient, from proximal to distal SOBP. The proton is a lower LET particle than other heavy-charged particles; for example, the mean LET values of the 65-MeV modulated proton beams (SOBP) are always less than 7 keV .m-' (Courdi et al, 1994).The achievement of uniformity of radiobiological effectiveness for target volumes is always a matter of concern. In fact, there is no uniformity of LET within target volumes. One study has suggested that DNA double-strand breaks, potentially lethal damage and sublethal damage, depend on LET and are closely

This study reports new hydrative carbocyclizations of 1,5- and 1,6-diyn-3-ones catalyzed by PPh3AuOTf, involving a pi-alkyne-assisted oxygen transfer in the reaction mechanisms. Treatment of 2-(alk-2-yn-1-onyl)-1-alkynylbenzenes with PPh3AuOTf (5 mol %) in wet 1,4-dioxane (23 degrees C, 10 min) led to hydrative aromatization to give 4-hydroxyl-1-naphthyl ketones efficiently. This approach is also extendible to the hydrative cyclization of acyclic 1,5-diyn-3-ones, which afforded 4-cyclopentenonyl ketones in reasonable yields. On the basis of this oxygen-labeling study, we propose a plausible mechanism involving an alkyne-assisted oxygen transfer to generate key oxonium and gold-enolate intermediates.