1,2-Dimethoxyethane → rac-(7aR,11aS)-11a-ethyl-2-methyl-7,7a,8,10,11,11a-hexahydro-6H-spiro[dibenzo[b,d]oxepine-9,2'-[1,3]dioxolan]-3-amine

Participants

Reaction Conditions

Reaction Steps

A 500 mL round-bottom flask equipped with air cooled reflux condenser outfitted with a nitrogen inlet adapter was charged with rac-(7aR,11aS)-2-bromo-11a-ethyl-7,7a,8,10,11,11a-hexahydro-6H-spiro[dibenzo[b,d]oxepine-9,2′-[1,3]dioxolan]-3-amine (87, R2=Ethyl) (9.14 g, 23.9 mmol), bis(triphenylphosphine)palladium(II) chloride (0.839 g, 1.20 mmol) and Cs2CO3 (23.4 g, 71.7 mmol), and then DME (180 mL), water (60 mL) and trimethylboroxine (6.67 mL, 47.8 mmol) were added. The reaction mixture was heated to about 90° C. for about 15 h. The reaction was allowed to cool to rt and then it was partitioned between EtOAc (350 mL) and water (200 mL). After separating the layers, the aqueous phase was extracted with EtOAc (2×100 mL). The combined organic phases were then washed with brine (500 mL), dried over Na2SO4, filtered, and concentrated under reduced pressure. The material was purified on silica gel (330 g, eluted with 0% to 50% EtOAc in heptane). Collection and concentration of the appropriate fractions gave rac-(7aR,11aS)-11a-ethyl-2-methyl-7,7a,8,10,11,11a-hexahydro-6H-spiro[dibenzo[b,d]oxepine-9,2′-[1,3]dioxolan]-3-amine (88, R2=Ethyl) (5.68 g, 74.8%) containing about 20% of a minor regioisomer. The material was used directly in Step #5 without further purification. LC/MS, method 3, 2.26 min, MS m/z 318 (M+H)+.

Provenance & Evidence