We report the application of our rhodium-catalyzed nucleophilic ring-opening methodology to unsymmetrically arene-substituted oxabenzonorbornadienes. The regioselectivity of the ring opening was investigated using a variety of nucleophiles that led to a broad selection of dihydronaphthalene products. It was found that good to excellent regioselectivities are obtained using strongly pi-donating substituents, whereas sigma-donating and electron-withdrawing functionalities have a minimal effect. Post ring-opening manipulations of functional groups in the dihydronaphthalene products were shown to give efficient access to mono- and diamine tetrahydronaphthalene building blocks.

Diastereoselective palladium-catalyzed formate reduction of allylic carbonates presents unique opportunities for applications in target-oriented organic synthesis provided that selectivity, in particular stereoselectivity, in the course of this metal-catalyzed reaction can be controlled. This article describes our recent developments on new and efficient metal-catalyzed processes exploiting resident stereocenters on the substrates as a means to control stereoselectivity en route to preparing propionate units containing an array of stereochemical patterns. In particular, the effect of the protecting group, the stereochemistry of the aldol adduct, neighboring substituents, and the olefin geometry were examined. Strategic choice of the above parameters provides entry into three of the four possible diastereomeric triads, namely syn-syn, anti-syn, and anti-anti. Preliminary results indicate that construction of the syn-anti triad is possible, albeit in moderate diastereoselectivity.

Hydrogenated naphthalene derivatives Hydrogenated naphthalene derivatives Q 1010Remote Electronic Effects in the Rhodium-Catalyzed Nucleophilic Ring Opening of Oxabenzonorbornadienes. -The regioselectivity of the ring-opening reaction of several unsymmetrically benzene-substituted oxabenzonorbornadienes is studied. Good to excellent regioselectivities are obtained for compounds bearing strongly π-donating substituents, whereas derivatives bearing σ-donating and electron-withdrawing substituents have a minimal effect. Two of the ring-opened products are further manipulated to give mono-and diamine tetrahydronaphthalene building blocks. -(LAUTENS*, M.; SCHMID, G. A.; CHAU, A.; J. Org. Chem. 67 (2002) 23, 8043-8053; Dep. Chem., Univ. Toronto, Toronto, Ont. M5S 3H6, Can.; Eng.) -Klein 17-089