“…After heating for 2 h, the reaction mixture was concentrated under reduced pressure and subjected to flash silica gel chromatography to give 0.13 g (69%) of cycloadduct 36 as a pale yellow oil; IR (neat) 2935, 2857, 1758, 1733, 1607, 1480, and 1252 4.30-4.40 (m, 2H), 7.14 (t, 1H, J = 7.3 Hz), and 7.34-7.41 (m, 3H); 13 C-NMR (100 MHz, CDCl 3 ) δ −3. 6,14.2,18.5,21.8,25.9,28.0,33.6,36.0,43.8,62.3,75.3,91.2,102.4,114.5,124.8,131.0,135.3,136.4,164.0,and 165.1;HRMS Calcd. for [C 24 H 33 NO 5 Si + H + ]: 444.2201.…”