Abstract
Diynes having malonate-based tethers react with arylboronic acids in the presence of a rhodium(I) catalyst to give 1,2-dialkylidenecycloalkanes. The regioselectivity of the initial carborhodation depends on the sterics and the directing nature of the alkyne substituents.
Key words
rhodium - cyclizations - addition reactions - arylboronic acids - diynes
References and Notes
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General Procedure for the Cyclization Reaction of 1a with 2: To an oven-dried, Ar-purged flask were added [Rh(OH)(cod)]2 (2.3 mg, 5.0 µmol, 5 mol% Rh), 1a (47.3 mg, 0.2 mmol), 2 (0.4 mmol), and dioxane-H2O (2.0 mL:0.1 mL). The reaction mixture was stirred at r.t. for 12 h, and quenched with addition of H2O (5 mL). The aqueous layer was extracted with EtOAc (5 × 6 mL). The combined extracts were washed with brine and dried over MgSO4. The solvent was removed under reduced pressure and the residue was purified by preparative TLC (hexane-EtOAc) to give 3.
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