Remote Electronic Effects in the Rhodium-Catalyzed Nucleophilic Ring Opening of Oxabenzonorbornadienes

Abstract

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.

An Alternative Method for Generating Arynes from ortho-Silylaryl Triflates: Activation by Cesium Carbonate in the Presence of a Crown Ether

“…1 H-NMR yields were determined using 1,1,2,2-tetrachloroethane as an internal standard. The spectra obtained for products 3 [28], 5a [43], 5b-d [44], 5e [45], 5f [46], 5g [47], 7 [28], 9 [28], 11 [28], and 13 [48] were identical to those reported in the corresponding references.…”

4-β-Azido-4-desoxypodophyllotoxin

“…The C1-C5/C10 ring displays a half-chair conformation, with atoms C2 and C3 deviating from the mean plane formed by the other four atoms by 0.415 (5) and À0.358 (5) Å , respectively. The bond distances and angles involving the azide group (Table 1) are comparable with those reported by Lautens et al (2002).…”

Iridium-Catalyzed Asymmetric Ring-Opening of Oxabenzonorbornadienes with N-Substituted Piperazine Nucleophiles

“…The substrates 1a – 1b were readily prepared by Diels-Alder reactions of benzynes with furan according to literature procedures [75]. To understand the nature of the catalytic ring-opening and optimize the reaction conditions, we first chose different chiral bisphosphine ligands, including ( S )-BINAP, ( R) -( S )-PPF-P t - Bu 2 , ( S )- p -Tol-BINAP, and ( S )-( R )-NMe 2 -PPh 2 -Mandyphos, to validate the catalytic activity of the iridium complexes.…”