Cu(I)-tert-butoxide; 9,9-dimethyl-4,5-bis(diphenyl-phosphino)xanthene; lithium tert-butylate in 2,2,4-trimethylpentane; toluene T=60°C; Inert atmosphere;

1: diisopropylamine With n-butyllithium in tetrahydrofuran T=-78 - 20°C; 1 h; 2: 2-naphthyl trifluoromethanesulfonate in tetrahydrofuran T=-78 - 20°C; thia-Fries rearrangement;

n-butyllithium T=-78°C; Yield given. Yields of byproduct given. Title compound not separated from byproducts;

n-butyllithium T=-78°C; Yield given. Yields of byproduct given. Title compound not separated from byproducts;

sulfur dioxide in water Bucherer reaction; 0.5 h; Irradiation;

1: dipotassium hydrogenphosphate; N,N-dimethyl-formamide / 25 °C / Inert atmosphere 2: Cu(I)-tert-butoxide; 9,9-dimethyl-4,5-bis(diphenyl-phosphino)xanthene; lithium tert-butylate / 2,2,4-trimethylpentane; toluene / 60 °C / Inert atmosphere View Scheme

diethyl ether; phenyllithium