3-Bromopyridine → 1,1-Dimethylethyl 1-(3-pyridinyl)-1,7-diazaspiro[4.4]nonane-7-carboxylate

Participants

Reaction Conditions

Reaction Steps

A mixture of tert-butyl 2,6-diazaspiro[4.4]nonane-2-carboxylate (1.00 g, ˜4.4 mmol), 3-bromopyridine (0.736 g, 4.66 mmol), potassium tert-butoxide (1.22 g, 10.9 mmol), tris(dibenzylideneacetone)dipalladium(0) (0.155 g, 0.169 mmol), 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (0.158 g, 0.254 mmol) and dry toluene (25 mL) was placed in a pressure tube under argon. The mixture was stirred and heated at 180° C. (bath temperature) for 8 h and cooled. Thin layer analysis indicated that very little conversion had taken place. A second charge, equal in quantity to the first, of all reagents except the tert-butyl 2,6-diazaspiro[4.4]nonane-2-carboxylate was added to pressure tube and the tube was returned to the bath for another 8 h. Again relatively little reaction seemed to have occurred, so a third charge of reagents was added and heating (at 180° C.) was continued for a third 8 h period. Water (20 mL) was added and the mixture was extracted with ethyl acetate (6×25 mL). The extracts were dried (K2CO3) and concentrated. Column chromatography of the residue on Merck silica gel 60 (70-230 mesh), with 6:4 (v/v) chloroform/acetone, gave 150 mg (˜11%) of light brown oil, after concentration of selected fractions.

Provenance & Evidence