To a solution of 2-(6-bromo-2,2-dimethyl-hexyloxy)-tetrahydro-pyran (13.0 g, 44.33 mmol) and p-toluenesulphonylmethyl isocyanide (4.33 g, 22.17 mmol) in anhydrous DMSO (50 ml) and anhydrous diethyl ether (50 ml) was added sodium hydride (60% dispersion in mineral oil, 2.13 g, 53.20 mmol) at rt under N2 atmosphere. After solidification of the reaction mixture, additional anhydrous DMSO (50 ml) was added. After stirring for 5.5 h at room temperature, tetrabutylammonium iodide (1.64 g, 4.43 mmol) was added and the mixture stirred for additional 22.5 h at rt. The reaction mixture was carefully hydrolyzed with water (10 ml), diluted with water (200 ml), and extracted with diethyl ether (200 ml). The organic layer was washed with saturated NaCl solution (100 ml), dried over MgSO4, and concentrated in vacuo to give crude 2-[7-isocyano-2,2,12,12-tetramethyl-13-(tetrahydro-pyran-2-yloxy)-7-(toluene-4-sulfonyl)- tridecyloxy]-tetrahydro-pyran (15.5 g) as an oil.
